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Biology and Management of
Threatened and Endangered Western Trouts
August 1976
USDA Forest Service
General Technical Report RM-28
Rocky Mountain Forest and
Range Experiment Station
Forest Service
U.S. Department of Agriculture
Fort Collins, Colorado 80521
Abstract
Behnke, R. J., and Mark Zarn.
1976. Biology and management of threatened and endangered western trouts.
USDA For. Sew. Gen. Tech. Rep. RM-28, 45 p. Rocky Mt. For. and Range
Exp. Stn., Fort Collins, Colo.
Discusses taxonomy, reasons for decline, life history and ecology, and suggestions for preservation and management of six closely related trouts native to
western North America: Colorado River cutthroat, Salmo clarki pleuriticus; greenback trout, S. c. stomias; Lahontan cutthroat, S. c. henshawi; Paiute trout, S. c.
seleniris; Gila trout, S. gilae; and Arizona native trout, S. apache. Meristic
characters, distribution and status, habitat requirements and limiting factors,
protective measures, and management recommendations are presented for each
taxon.
Keywords: Native trout, Salrno clarki pleuriticus. Sali?zo ckurki stoi~zius. Sulnzo
clarki herzshawi, Salmo clarki seleniris, Salrno gilue. Sulrno uprrchc.
USDA Forest Service
General Technical Report RM-28
August 1976
Biology and Management of Threatened and
Endangered Western Trouts
R. J. Behnke
Colorado State University
Mark Zarn
Conservation Library
Denver Public Library
Information reported here was prepared under contract by the Conservation Library of the Denver
Public Library, through the Rocky Mountain Forest and Range Experiment Station. The report is
printed as prepared by the authors; opinions are not necessarily those of the U.S. Forest Service.
TABLE OF CONTENTS
I
.
11
I11
.
.
IV
.
V
.
AND ENDANGJIRED WESTERN TROUTS
Introduction
Taxonomy
Reasons for Decline
Life History and Ecology
Preservation. Restoration and Management Programs
Potential Role of Native Trout in Fisheries Management
Summary
Authorities
References
GJ3NERAL MANAGEMENT GUIDELINES FOR RAE3
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COLORADO R I m R CUTTHROAT TROUT. Salmo clarki pleuriticus
Typical Meristic Characteristics *
Species Description
Distribution
Status and Population Trend
LifeHistory
Habitat Requirements and Limiting Factors
Protective Measures
Recommendations
Authorities
References
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W N B A C K CUTTHROAT TROUT. Salmo clarki stomias
Typical Meristic Characteristics
Species Description
Distribution
Status and Population Trend
Life History
Habitat Requirements and Limiting Factors
Protective Measures
Recommendations
Authorities
References
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LAHONTAN CUTTHROAT TROUT. Salmo clarki henshawi
Typical Meristic Characteristics
Species Description
Distribution
Status and Population Trend
Life History
Habitat Requirements and Limiting Factors
Protective Measures
Recommendations
Authorities
References
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PAIUTE TROUT. SaLmo clarki seleniris
Typical Meristic Characteristics
Species Description
Distribution
Status and Population Trend
Life History
Habitat Requirements and Limiting Factors
Protective Measures
Recommendations
Authorities
References
. . . . . . . . . . . . . . . . . . . . . . 32
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35
TABLE OF CONTENTS (CONT'D)
VI
VII
.
.
GILA TROUT. Salmo ailae
Typical Meristic Characteristics
Species Description
Distribution
Status and Population Trend
Life History
Habitat Requirements and Limiting Factors
Protective Measures
Recommendations
Authorities
References
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ARIZONA NATIVE TROUT. Salmo apache
Typical Meristic Characteristics
Species Description
Distribution
Status and Population Trend
Life History
Habitat Requirements and Limiting Factors
Protective Measures
Recommendations
Authorities
References
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36
36
38
39
39
39
BIOLOGY AND MANAGEMENT OF THREATENED AND ENDANGERED WESTERN TROUTS
This r e p o r t d i s c u s s e s t h e biology and
management of s i x c l o s e l y r e l a t e d t r o u t s
n a t i v e t o western North America. A l l s h a r g
many common e c o l o g i c a l and g e n e t i c a t t r i b u t e s ;
a l l have s u f f e r e d c a t a s t r o p h i c d e c l i n e s i n
abundance due t o e s s e n t i a l l y s i m i l a r f a c t o r s .
The folLowing s e c t i o n p r e s e n t s g e n e r a l i n formation a p p l i c a b l e t o a l l of t h e s e t r o u t s
and r e l e v a n t t o any meaningful p r e s e r v a t i o n ,
r e s t o r a t i o n and management e f f o r t s . Succeeding c h a p t e r s p r e s e n t more s p e c i f i c b i o l o g i c a l
and management c o n s i d e r a t i o n s f o r each t a x a .
Man s t i l l l a c k s complete knowledge o f
the e v o l u t i o n a r y h i s t o r y which r e s u l t e d i n
the d i v e r s e a r r a y o f western North American
t r o u t s of t h e genus Salmo. E a r l i e r thought
considered t h a t a l l western t r o u t s e i t h e r
belonged t o o r r e c e n t l y derived from two
e v o l u t i o n a r y l i n e s o r s p e c i e s : t h e rainbow
t r o u t , Salmo g a i r d n e r i , and t h e c u t t h r o a t
t r o u t , 2. c l a r k i . Recent s t u d i e s have demons t r a t e d t h a t t h e t r u e s i t u a t i o n i s much more
complex; s e v e r a l d i s t i n c t groups i n c l u d i n g
(.g i l a e ) , Arizona n a t i v e
the G i l a t r o u t S
t r o u t (5. apache), Mexican golden t r o u t
(Salmo c h r y s o g a s t e r ) , C a l i f o r n i a golden t r o u t
(Salmo aguabonita) and redband t r o u t (not
o f f i c i a l l y named) do n o t f i t t h e d i a g n o s i s of
e i t h e r t h e rainbow t r o u t o r t h e c u t t h r o a t
t r o u t and probably r e p r e s e n t d i s t i n c t evolut i o n a r y l i n e s of t h e i r own which s p r a n g from
a common a n c e s t o r t o a l l w e s t e r n Salmo
(Behnke 1972b, Schreck and Behnke 1971,
M i l l e r 1972).
D e s p i t e such e v o l u t i o n a r y d i v e r s i t y , a l l
western t r o u t s a r e c l o s e l y r e l a t e d t o t h e
e x t e n t t h a t they can i n t e r b r e e d f r e e l y w i t h
each o t h e r t o produce f e r t i l e h y b r i d s . Only
i n P a c i f i c Coast r i v e r s , where rainbow t r o u t
and t h e c o a s t a l c u t t h r o a t , 5. c. c l a r k i ,
r e s i d e t o g e t h e r and i n t h e Salmon and C l e a r water d r a i n a g e s of t h e Columbia R i v e r b a s i n
of Idaho where r e s i d e n t i n t e r i o r c u t t h r o a t
occur w i t h anadromous s t e e l h e a d t r o u t
(5. g a i r d n e r i ) does c o e x i s t e n c e occur n a t u r a l l y
In a l l i n s t a n c e s where
without h y b r i d i z a t i o n .
t h e rainbow t r o u t has been e s t a b l i s h e d beyond
i t s n a t i v e range and stocked w i t h G i l a t r o u t ,
golden t r o u t o r any of t h e i n t e r i o r subspecies
of c u t t h r o a t t r o u t , h y b r i d i z a t i o n has i n v a r i a b l y
r e s u l t e d . The i n d i s c r i m i n a t e s t o c k i n g of
u n t o l d m i l l i o n s of rainbow t r o u t and s e v e r a l
subspecies of c u t t h r o a t t r o u t i n t o v i r t u a l l y
every h a b i t a b l e water throughout t h e West, and
subsequent h y b r i d i z a t i o n w i t h t h e n a t i v e t r o u t
fauna, has been t h e primary cause f o r t h e
almost complete e l i m i n a t i o n of pure populations
of most of t h e taxonomic c a t e g o r i e s of n a t i v e
t r o u t s i n t h e i n t e r i o r r e g i o n s of t h e West.
The presence of a l l degrees of h y b r i d i z a t i o n g r e a t l y confounds t h e work of c o r r e c t l y
i d e n t i f y i n g a n d e v a l u a t i n g t h e p u r i t y of e x i s t i n g p o p u l a t i o n s of n a t i v e t r o u t i n most r e g i o n s ,
and t h e r e c o g n i t i o n of pure s t o c k s of any of
t h e s i x t r o u t s considered i n t h i s r e p o r t i s
n o t a simple m a t t e r . Although one can a c q u i r e
s u f f i c i e n t familiarity with the subtle variat i o n s among t h e d i f f e r e n t s p e c i e s and subs p e c i e s of western t r o u t s t o d i s t i n g u i s h t h e
v a r i o u s t a x a , t h e average f i e l d worker cannot
b e expected t o a c c u r a t e l y d i f f e r e n t i a t e t h e
t r u e n a t i v e t r o u t of a given a r e a from h y b r i d
p o p u l a t i o n s . Taxonomic c r i t e r i a e x i s t f o r a l l
t h e t r o u t s i n t h i s r e p o r t , but t h e s o r t i n g and
e v a l u a t i o n of specimens c o l l e c t e d d u r i n g survey
work t o determine t h e s t a t u s of a n a t i v e t r o u t
and t o l o c a t e pure populations remains a n i n volved process of d e t a i l e d examination and
comparison of twr~yc h a r a c t e r s .
So u n l e s s a n agency i s d e a l i n g w i t h
" c e r t i f i e d " pure popqlations i n a r a r e t r o u t
management program, i t w i l l u l t i m a t h l l c o n f r o n t
t h e problem of i d e n t i f i c a t i o n . P o s s i b i l i t i e s
f o r a d d i t i o n a l refinement of information u s e f u l
i n taxonomic i d e n t i f i c a t i o n e x i s t ; t h e s e i n clude biochemical techniques such a s p r o t e i n
e l e c t r o p h o r e s i s and karyotype examination-t h e d e t e r m i n a t i o n o f chromosome number and
morphology. Yet t h e i n v e s t i g a t o r should use
c a u t i o n i n u t i l i z i n g t h e s e modern techniques
t o determine t h e r e l a t i v e p u r i t y of t r o u t
p o p u l a t i o n s , f o r they r e q u i r e both a Icnowledge
of b a s i c p r i n c i p l e s of taxonomy and a f a m i l i a r i t y w i t h the n a t u r a l range of v a r i a b i l i t y of
t h e t r o u t under study. Often, i f t h e e x t e n t
of h y b r i d i z a t i o n has reached a l e v e l where i t
can be d e t e c t e d by e l e c t r o p h o r e s i s o r a l t e r a t i o n s i n t h e chromosome compleaent, i t w i l l
a l s o show up i n t h e form of changes i n dent i t i o n , s p o t t i n g p a t t e r n , s c a l e counts and
o t h e r morphological c h a r a c t e r s .
a l s o favor t h e displacement of n a t i v e t r o u t s
by more t o l e r a n t introduced s p e c i e s , n o t a b l y
t h e brook t r o u t ( S a l v e l i n u s f o n t i n a l i s ) and
t h e brown t r o u t (Salmo t r u t t a ) .
Most pure n a t i v e t r o u t populations i n
t h e i n t e r i o r r e g i o n s of t h e West p e r s i s t only
i n s m a l l i s o l a t e d headwater stream s i t u a t i o n s
i n e s s e n t i a l l y undisturbed h a b i t a t .
LIFE HISTORY AND ECOLOGY
The l a c k of r e p r o d u c t i v e i s o l a t i o n and
t h e l a c k of c l e a r - c u t d i a g n o s t i c f e a t u r e s ,
has r a i s e d q u e s t i o n s concerning t h e v a l i d i t y
of t h e recognized t a x a of western t r o u t s .
The most p e r t i n e n t a d v i c e r e l e v a n t t o
management p o l i c i e s f o r any t r o u t under cons i d e r a t i o n i s t o i g n o r e o r avoid q u e s t i o n s
concerning t h e v a l i d i t y of z o o l o g i c a l nomenc l a t u r e , w h i l e recognizing t h a t each of t h e s e
t r o u t s i s indeed a n e v o l u t i o n a r y r e a l i t y .
That i s , i t has become a n i n t e g r a l p a r t of
t h e b i o l o g i c a l and e v o l u t i o n a r y h e r i t a g e of a
given geographical a r e a as a r e s u l t of its
unique g e n e t i c programming under t h e n a t u r a l
s e l e c t i o n which has taken p l a c e during i t s
long i s o l a t i o n and divergence from a n c e s t r a l
t r o u t fauna. A l l of t h e s i x taxa of t r o u t
d i s c u s s e d i n t h i s r e p o r t f a l l w i t h i n the
province of t h e Endangered Species Act of
1973 (P.L. 93-205) which d e f i n e s a s p e c i e s t o
i n c l u d e "subspecies, s m a l l e r taxa o r any
p o p u l a t i o n segment t h e r e o f
Thus, t h e
v a l i d i t y of a s p e c i e s o r subspecies should
n o t o b s t r u c t p r o t e c t i v e measures f o r a r a r e
t r o u t ; t h e major c o n s i d e r a t i o n ought t o be
t h a t t h e t r o u t r e p r e s e n t s a segment of a
s p e c i e s indigenous t o a p a r t i c u l a r geographical area.
."
Behnke (1972a) and Trojnar and Behnke
(1974) have d i s c u s s e d t h e r a t i o n a l e and p r a c t i c a l v a l u e of p r e s e r v i n g t h e remaining
g e n e t i c d i v e r s i t y of o u r n a t i v e western t r o u t s .
REASONS FOR DECLINE
W e mentioned t h a t t h e h y b r i d i z a t i o n
caused by massive i n t r o d u c t i o n of rainbow
t r o u t and subspecies o f c u t t h r o a t t r o u t i n t o
waters i n which they were n o t n a t i v e has l e d
t o t h e v i r t u a l e l i m i n a t i o n of pure populations
of t h e t r o u t s under d i s c u s s i o n i n t h i s r e p o r t .
H a b i t a t l o s s and d e g r a d a t i o n a s a r e s u l t of
i r r i g a t i o n p r o j e c t s , mining, logging, road
b u i l d i n g and overgrazing have a l s o taken t h e i r
t o l l , p a r t i c u l a r l y i n t h e a r i d r e g i o n s of t h e
West. These f a c t o r s have n o t only g r e a t l y
reduced t h e amount of s u i t a b l e h a b i t a t , b u t
A l l o f our western t r o u t s a r e h i g h l y
a d a p t a b l e ; they can l i v e i n a v a r i e t y of
environments ranging from small brooks t o
l a r g e r i v e r s and l a k e s , and they feed on a
broadrspectrum of organisms. This wide range
of a d a p t a b i l i t y makes i t h i g h l y misleading t o
b a s e t h e e c o l o g i c a l c h a r a c t e r i s t i c s of an
e n t i r e taxon on d a t a taken from a p o p u l a t i o n
i n a s p e c i f i c h a b i t a t . A11 t r o u t s a r e opport u n i s t i c and e c l e c t i c i n t h e i r d i e t , which
e s s e n t i a l l y r e f l e c t s t h e a v a i l a b i l i t y of food
organisms i n t h e i r p a r t i c u l a r environment.
Growth depends p r i m a r i l y on food a v a i l a b i l i t y ,
s i z e of p r e y , t h e degree of i n t r a s p e c i f i c and
i n t e r s p e c i f i c competition, water temperatures,
and t h e l e n g t h of t h e growing season. Fecundity,
i n t u r n , depends on s i z e . The l i f e h i s t o r y
and e c o l o g i c a l t r a i t s of two neighboring popul a t i o n s of t h e same subspecies l i v i n g i n d i s t i n c t l y d i f f e r e n t environments w i l l d i f f e r
much more from each o t h e r than from those of
d i f f e r e n t t r o u t species living i n e s s e n t i a l l y
s i m i l a r environments. One must be aware t h a t
d i f f e r e n t genotypes allow f o r a broad and
l a b i l e range of e c o l o g i c a l o p t i o n s ; t o assume
t h a t s p e c i f i c food h a b i t s , growth r a t e ,
f e c u n d i t y o r o t h e r c h a r a c t e r i s t i c s of a
given population under s t u d y r e p r e s e n t g e n e t i c a l l y "fixed" a t t r i b u t e s of t h e taxon as a
whole i s a misconception. The s i g n i f i c a n c e of
t h i s point i n r e l a t i o n t o restoration e f f o r t s
which aim t o expand t h e range of a r a r e t r o u t
i s t h a t w a t e r s with p o t e n t i a l f o r r e i n t r o d u c t i o n
need n o t c l o s e l y match t h e c o n d i t i o n s of t h e
waters of t h e p o t e n t i a l donor population. With
t h e c o n d i t i o n t h a t no non-native t r o u t s a r e
p r e s e n t , v i r t u a l l y any waters s u i t a b l e f o r any
t r o u t s p e c i e s can s e r v e a s s u i t a b l e h a b i t a t
f o r any of t h e s i x t r o u t s t r e a t e d i n t h i s r e p o r t . One n o t a b l e exception i n a d a p t a b i l i t y
t o environmental extremes e x i s t s i n t h e
Lahontan c u t t h r o a t t r o u t , which can t o l e r a t e
tremendous ranges i n a l k a l i n i t y and f l o u r i s h
i n w a t e r s such a s Walker Lake, Nevada, under
conditions l e t h a l t o a l l other trouts.
A11 o f t h e non-domesticated western
t r o u t s of t h e genus Salmo spawn i n t h e s p r i n g ;
i n c r e a s i n g water temperatures t r i g g e r r e p r o d u c t i o n . Most spawning a c t i v i t y begins when
-
water temperatures r e a c h 5 . 5
9 . 0 ~C . Elevat i o n and l a t i t u d e a l s o i n f l u e n c a t h e o n s e t of
which may occur a s e a r l y a s March o r
A p r i l i n some a r e a s and extend w e l l i n t o June
and J u l y i n o t h e r s . The n e c e s s i t y of g r a v e l
f o r n e s t c o n s t r u c t i o n and high oxygen t e n s i o n s
f o r t h e developing embryos makes a l l of t h e
t r o u t s under c o n s i d e r a t i o n e s s e n t i a l l y o b l i g a t o r y s t r e a m spawners. Fry emerge from n e s t s
i n e a r l y t o mid-summer, depending on when
spawning occurs; l e n g t h of t h e growing season
d i c t a t e s s i z e , which reaches 2.5 t o 7.5 cm
by autumn. F i s h six t o e i g h t y e a r s o l d may
a t t a i n a l e n g t h of l e s s than 25 cm i n s m a l l
streams w i t h r e s t r i c t e d h a b i t a t s and dense
but i n l a r g e r i v e r s and l a k e s
c a n be r a p i d w i t h t r o u t r e a c h i n g
s e v e r a l pounds i n weight by t h e f o u r t h o r
f i f t h year. The l a s t spawning r u n , i n 4 9 3 8 ,
of t h e n a t i v e c u t t h r o a t of Pyramid Lake,
Nevada, r e v e a l e d a n average w e i g h t of 9.0 kg
f o r spawning f i s h , most of which were seven
t o e i g h t y e a r s o l d (Sumner 1940); t r o u t of
the same s u b s p e c i e s l i v i n g i n headwater
streams may n o t exceed 25 cm i n l e n g t h .
Sexual m a t u r i t y t y p i c a l l y occurs a t a n
age of two t o f o u r y e a r s . I n s m a l l s trearn
populations mature t r o u t may o n l y be 15 t o
20 cm i n l e n g t h and spawn only 100-200 eggs.
A g e n e r a l i z a t i o n on f e c u n d i t y , w i t h wide
i n d i v i d u a l v a r i a t i o n , i s t h a t females w i l l
spawn about 1000 eggs p e r 450 gms of body
weight.
P r e s e n t p o p u l a t i o n s of t h e s e t r o u t probably cannot p e r s i s t i n w a t e r s where maxilnum
temperatures c o n s i s t e n t l y exceed 21-22'
C.
But they may possess t o l e r a n c e t o s u r v i v e ,
under stress, b r i e f d a i l y p e r i o d s of h i g h e r
26.7' C.) i f t h e w a t e r s
temperatures (25.5
s i g n i f i c a n t l y cool a t n i g h t . The p a t t e r n of
replacement of n a t i v e t r o u t s by i n t r o d u c e d
brook, brown and rainbow t r o u t throughout t h e
i n t e r i o r West i n d i c a t e s t h a t t h e n a t i v e t r o u t s
p r e f e r and f u n c t i o n b e s t a t lower temperatures
than do o t h e r s p e c i e s . With few e x c e p t i o n s ,
n a t i v e c u t t h r o a t t r o u t c o e x i s t w i t h and
dominate i n t r o d u c e d s p e c i e s o n l y i n c o l d ,
headwater s i t u a t i o n s . Thus, c l e a r c u t t i n g and
overgrazing, which remove v e g e t a t i v e cover
and warm t h e w a t e r s , w i l l f a v o r t h e r e p l a c e ment of n a t i v e t r o u t s by o t h e r forms.
-
I n Oregon, a f t e r c l e a r c u t t i n g of a watershed, w a t e r temperatures i n c r e a s e d due t o
lack of c o v e r , and d i s s o l v e d oxygen i n t h e
spawning g r a v e l decreased due t o s i l t a t i o n .
This d i d n o t s i g n i f i c a n t l y a f f e c t t h e coho
salmon p o p u l a t i o n , b u t t h e c u t t h r o a t t r o u t
populatioa s u f f e r e d a d e c l i n e of two-thirds
i n number d u r i n g s i x y e a r s of a follow-up
study (Ringler and H a l l 1975).
C u t t h r o a t t r o u t , and perhaps G i l a t r o u t
and Arizona t r o u t a s w e l l , s u f f e r from a h i g h
v u l n e r a b i l i t y t o a n g l i n g . I n a s m a l l Idaho
stream, 32 man-hours of f i s h i n g removed 50 perc e n t of t h e c u t t h r o a t t r o u t and only 25 p e r c e n t
of t h e brook t r o u t 15 cm and over i n l e n g t h
(McPhee 1966). I n New Mexico t h e n a t i v e t r o u t
of t h e Rio Chiquito dominated t h e i n t r o d u c e d
brown t r o u t by 420 t o 37 i n samples made i n
1965-1966, when t h e s t r e a m was on p r i v a t e
land and c l o s e d t o f i s h i n g ( L i t t l e and McKirdy
1968). I n 1969, two y e a r s a f t e r t h e U. S .
F o r e s t S e r v i c e had a c q u i r e d t h e Land and
opened t h e s t r e a m t o a n g l i n g , sampling r e v e a l e d
t h a t t h e r a t i o had been d r a s t i c a l l y reversed-137 brown t r o u t v e r s u s 37 c u t t h r o a t t r o u t - due t o t h e d i f f e r e n t i a l v u l n e r a b i l i t y of t h e
two s p e c i e s t o a n g l i n g u Management programs
f o r n a t i v e t r o u t can b e n e f i t from t h i s a n g l i n g
v u l n e r a b i l i t y , however, by e s t a b l i s h i n g
s p e c i a l r e g u l a t i o n catch-and-release f i s h e r i e s ,
o r by r e s t r i c t i n g s i z e and bag l i m i t s , a s
d i s c u s s e d below ( s e e pages 7-8).
PRESERVATION, RESTORATION AND
MANAGEMENT PROGRAMS
It o f t e n seems d i f f i c u l t t o i n i t i a t e
meaningful r a r e t r o u t r e s t o r a t i o n programs,
b u t w h i l e r e a l problems and o b s t a c l e s e x i s t ,
workers c a n overcome them i f t h e y develop a
s e t of p r i o r i t i e s and g o a l s and recommend t h a t
s p e c i f i c a c t i o n s be c a r r i e d o u t . It remains
a r e l a t i v e l y simple m a t t e r t o t r a n s p l a n t t r o u t
from a remnant p o p u l a t i o n i n t o new w a t e r s - e i t h e r b a r r e n o r where a l l o t h e r f i s h have
been e l i m i n a t e d - - i n o r d e r t o e s t a b l i s h a new
population.
The f i r s t s t e p i n most r e s t o r a t i o n programs f o r r a r e , n a t i v e t r o u t - - t h a t of i d e n t i f i c a t i o n - - i n v o l v e s a survey and i n v e n t o r y of
w a t e r s where t h e r e i s a l i k e l i h o o d of encount e r i n g pure p o p u l a t i o n s . Remote and i s o l a t e d
headwater a r e a s , p a r t i c u l a r l y above b a r r i e r
f a l l s and w i t h o u t t r i b u t a r y l a k e s (which s e r v e
a s popular t a r g e t a r e a s f o r i n t r o d u c t i o n s of
exotic trouts) , offer the greatest potential
f o r n a t i v e t r o u t p o p u l a t i o n r e s e r v e s . When
t r o u t i n such w a t e r s appear t o resemble t h e
d i a g n o s i s of t h e n a t i v e t r o u t , c o l l e c t 10-20
specimens from each i s o l a t e d s i t e and p r e s e r v e
them i n 10 p e r c e n t formalin. I n t h e f i e l d ,
wrap specimens i n formalin-soaked c l o t h and
i n j e c t f o r m a l i n i n t o t h e body c a v i t y w i t h a
hypodermic s y r i n g e . Comparative examination
of t h e s e c o l l e c t i o n s can b e g i n t o i d e n t i f y
-
'/ McKirdy, H. J. Rio Chiquito p o p u l a t i o n
survey. Carson N a t i o n a l F o r e s t memorandum.
22 August 1969.
t h o s e p o p u l a t i o n s most c l o s e l y conforming t o
t h e d i a g n o s i s of t h e taxon involved. Graduate
r e s e a r c h t h e s i s p r o j e c t s through u n i v e r s i t i e s
can o f f e r r e l a t i v e l y e f f i c i e n t and economical
means of handling survey and i d e n t i f i c a t i o n
worlc. Once r e s e a r c h e r s e s t a b l i s h t h e r e l a t i v e
p u r i t y , d i s t r i b u t i o n and abundance of t h e
n a t i v e forms, t h o s e populations judged t o be
uncontaminated by h y b r i d i z a t i o n can be given
s p e c i a l c o n s i d e r a t i o n i n land u s e d e c i s i o n s
and environmental impact a n a l y s i s , and s e r v e
a s a source f o r specimens f o r i n t r o d u c t i o n s t o
i n c r e a s e t h e i r abundance.
Unnecessary d e l a y s and p r o c r a s t i n a t i o n
t y p i c a l l y begin a t t h i s s t a g e , when s p e c i f i c
n a t i v e populations have been i d e n t i f i e d .
Many b e l i e v e t h a t they must i n i t i a t e l i f e
h i s t o r y and h a b i t a t s t u d i e s b e f o r e any management d e c i s i o n s o r t r a n s p l a n t s can t a k e p l a c e .
The o b j e c t i v e s a r e t o g a t h e r d e t a i l e d d a t a on
a g e , growth, food h a b i t s , f e c u n d i t y and o t h e r
l i f e h i s t o r y c h a r a c t e r i s t i c s of t h e t r o u t
p o p u l a t i o n , and on t h e b i o l o g i c a l , p h y s i c a l
and chemical parameters of t h e w a t e r s i n which
they l i v e , w i t h t h e i d e a t h a t once t h i s knowl e d g e becomes a v a i l a b l e i n t e l l i g e n t and s c i e n t i f i c management can begin. I f t h e l i f e
h i s t o r y c h a r a c t e r i s t i c s of t r o u t were g e n e t i c a l l y f i x e d t r a i t s , and i f t h e environmental
parameters measured composed a t r u e r e f l e c t i o n
of t h e l i m i t s f o r s u r v i v a l , t h i s would be a
l o g i c a l course of a c t i o n ; b u t i n f a c t they
a r e n o t . Such i n f o r m a t i o n u s u a l l y has l i t t l e
meaning when p r e d i c t i n g t h e success of a
t r a n s p l a n t i n t o new w a t e r s , except where b a s i c
i n f o r m a t i o n i s needed t o maintain a n abundance
of t r o u t and a d e s i r a b l e age s t r u c t u r e i n a
p o p u l a t i o n exposed t o e x p l o i t a t i o n i n a
s p e c i a l r e g u l a t i o n s f i s h e r y program.
I f a survey determines t h a t pure populat i o n s of a n a t i v e t r o u t a r e r a r e and r e s t r i c t e d
t o a few i s o l a t e d s t o c k s , then f i r s t p r i o r i t y
should be t o e f f e c t t r a n s p l a n t s i n t o new
waters w i t h i n t h e i r n a t i v e range, b e f o r e
n a t u r a l o r man-caused c a t a s t r o p h e s can f u r t h e r
decimate t h e remnant s t o c k s . A f t e r t h e e s t a b lishment of populations i n new w a t e r s , l i f e
h i s t o r y s t u d i e s and environmental a n a l y s e s
can i n c l u d e both donor and r e c i p i e n t populat i o n s and t h e i r environments. Such information
would have g r e a t e r p r e d i c t i v e v a l u e s i n c e i t
would o f f e r more i n s i g h t i n t o t h e range of
a d a p t i v e responses o f t h e t r o u t under s t u d y .
N a t u r a l l y b a r r e n waters above b a r r i e r s ,
which prevent mixing w i t h introduced t r o u t s ,
c o n s t i t u t e i d e a l s i t e s f o r e s t a b l i s h i n g new
populations.
Such l o c a t i o n s s t i l l e x i s t ,
though they a r e r a r e . The expense and e f f o r t s
of e f f e c t i n g a t r a n s p l a n t of t h i s n a t u r e i n volves only t h e c o l l e c t i o n and t r a n s p o r t of
l i v e f i s h . Note t h a t some b a r r e n headwater
streams, p a r t i c u l a r l y a t high e l e v a t i o n s ,
appear t o provide s u i t a b l e h a b i t a t f o r t r o u t
i n summer, b u t l a c k pools and cover s u f f i c i e n t
t o s u c c e s s f u l l y c a r r y t h e f i s h through a hard
w i n t e r . I n t h e s e s i t u a t i o n s t h e t r o u t migrate
from t h e a r e a and w i l l n o t maintain a permanent
p o p u l a t i o n (Bjornn 1971). H a b i t a t improvement
i n headwater a r e a s i s f e a s i b l e when i t involves
c r e a t i n g pools and cover t o provide support
f o r a permenent f i s h population (Gard 1961,
1972).
Many more streams e x i s t which support
i n t r o d u c e d t r o u t s o r h y b r i d s above a n a t u r a l
b a r r i e r ; they too o f f e r good p o s s i b i l i t i e s for
e s t a b l i s h m e n t of n a t i v e t r o u t populations with
minimal e f f o r t and expense. No doubt e x i s t s
t h a t t h e s e streams can support t h e transplanted
t r o u t a f t e r t h e complete e l i m i n a t i o n of a l l
o t h e r f i s h . Use antimycin o r rotenone i n
s m a l l streams t o completely k i l l a l l f i s h ,
t a k i n g c a r e t o t r e a t a l l p o s s i b l e r e f u g e areas
such a s backwater a r e a s of beaver ponds and
s p r i n g s e e p s . The National Park S e r v i c e used
t h i s technique i n Rocky Mountain National Park
i n e l i m i n a t i n g t h e brook t r o u t from Hidden
Valley t o r e - e s t a b l i s h t h e greenback c u t t h r o a t
trout.
I f no n a t u r a l b a r r i e r e x i s t s on a n o t h e r w i s e s u i t a b l e stream, i t i s p o s s i b l e t o cons t r u c t a n a r t i f i c i a l b a r r i e r o r t o b l a s t one
o u t of a r o c k s u b s t r a t e . Follow b a r r i e r cons t r u c t i o n w i t h chemical treatment above t h e
stream, t o e l i m i n a t e unwanted f i s h e s , b e f o r e
t h e i n t r o d u c t i o n o f n a t i v e t r o u t . Workers
used t h i s technique t o r e - e s t a b l i s h greenback
t r o u t i n Black Hollow Creek, Colorado, and
Gila t r o u t i n McKnight Creek, New Mexico.
Another v i a b l e p o s s i b i l i t y i n any r a r e
t r o u t r e i n t r o d u c t i o n program i s t h e e s t a b l i s h ment of populations i n newly c o n s t r u c t e d lakes
t o e s t a b l i s h a unique f i s h e r y under s p e c i a l
r e g u l a t i o n s . Christmas Tree Lake on t h e
Apache I n d i a n R e s e r v a t i o n , Arizona, stocked
w i t h Arizona n a t i v e t r o u t , s e r v e s a s a n
example of t h i s method. Lake populations
o f f e r a n abundant and e a s i l y o b t a i n a b l e source
of eggs f o r propagation, and can g r e a t l y
f a c i l i t a t e new i n t r o d u c t i o n s .
Some d i f f i c u l t i e s may e x i s t i n e s t a b l i s h i n g a new population from t r a n s p l a n t s of a
few a d u l t f i s h i n t o a new environment, part i c u l a r l y i n s m a l l headwater streams without
deep pools above a b a r r i e r . The n a t u r a l t e n dency of a d i s p l a c e d f i s h i s t o r e t u r n t o t h e
p l a c e of i t s o r i g i n , and most may soon migrate
downstream over t h e b a r r i e r . Trout movement
i s a l s o more pronounced d u r i n g p e r i o d s o f low
o r d e c r e a s i n g temperatures (Bjornn 1971). Once
n a t u r a l r e p r o d u c t i o n has occurred i n t h e new
t h e success of t h e i n t s o d u c t i o n
should be a s s u r e d , b a r r i n g some c a t a s t r o p h e .
P a r t i c u l a r l y i n a r i d r e g i o n s where streams
c h a r a c t e r i s t i c a l l y d i s p l a y i n t e r m i t t e n t summer
flows and l a c k s u i t a b l e pools and cover, stream
improvement devices can promote i n c r e a s e d
abundance of t r o u t by c r e a t i n g t r o u t h a b i t a t
where none p r e v i o u s l y e x i s t e d . Stream improvement devices o f t e n r e q u i r e a c o n s i d e r a b l e
investment of money, time and l a b o r , b u t t h e
i n t h e 1930's of such devices i n
Diamond Creek, New Mexico, by C i v i l i a n Cons e r v a t i o n Corps personnel may have saved t h e
Gila t r o u t i n t h i s stream from e x t i n c t i o n
during subsequent drought y e a r s when v i r t u a l l y
the e n t i r e population was r e s t r i c t e d t o t h e
pools c r e a t e d by t h e small dams.
S u c c e s s f u l stream h a b i t a t management
improves l i v i n g c o n d i t i o n s i n t h e w a t e r s and
i n c r e a s e s s u r v i v a l , growth and r e p r o d u c t i o n
of t r o u t . Good t r o u t h a b i t a t provides s h e l t e r
from p r e d a t o r s , f e r t i l e w a t e r , adequate l i v i n g
space, proper water temperature, and g r a v e l
i n t h e streambed f o r spawning. Proper stream
management, e s p e c i a l l y when i t i n v o l v e s t h e
c o n s t r u c t i o n of in-stream improvement d e v i c e s ,
i s b o t h r e l a t i v e l y expensive and r e l a t i v e l y
complicated, and remains a job f o r p r o f e s s i o n a l s
who a r e both well-versed i n fundamental t r o u t
ecology and f a m i l i a r w i t h h a b i t a t management
techniques. Every stream h a s i t s i n d i v i d u a l
problems and c h a r a c t e r i s t i c s , and t o proceed
with h a b i t a t a l t e r a t i o n p r o j e c t s t o "improve"
a stream w i t h o u t a thorough knowledge of
a v a i l a b l e methods, t h e p h y s i c a l , chemical and
b i o l o g i c a l parameters of t h e w a t e r s i n q u e s t i o n ,
and t h e e c o l o g i c a l c h a r a c t e r i s t i c s of the
r e s i d e n t f i s h p o p u l a t i o n , c a n do more harm
than good. A h a b i t a t improvement team should
c o n s i s t of b i o l o g i s t s s k i l l e d i n h a b i t a t
development, t e c h n i c i a n s f a m i l i a r w i t h surveying and mapping techniques, and foremen
experienced i n c a r p e n t r y and mechanics (White
and Brynildson 1967). Space does n o t permit
a thorough d i s c u s s i o n of h a b i t a t improvement
techniques h e r e ; s e v e r a l e x c e l l e n t papers
e x i s t t o f a m i l i a r i z e personnel w i t h t h i s
topic (see: Boreman 1974, Packer 1957,
J e s t e r and McKirdy 1966, Gee 1952, Hunt 1969,
White and Brynildson 1967, Jackson 1974).
A survey o f streams i n a n a r e a t o l o c a t e
those having p o t e n t i a l f o r improvement cons t i t u t e s t h e f i r s t s t e p i n a n o r d e r l y management sequence. Examination of streams should
proceed on a n i n d i v i d u a l b a s i s and t a k e i n t o
account t h e c h a r a c t e r i s t i c s of t h e e n t i r e
stream c o u r s e , and n o t j u s t t h o s e s e c t i o n s
obviously i n need of management. I n t h i s
way many problems can be avoided, such a s
c o n s t r u c t i o n of pools over t h e only adequate
d e p o s i t s of spawning g r a v e l i n t h e stream.
Diagnosis of s p e c i f i c problems i n t h e stream
l e a d s t o a p r e s c r i p t i o n o f , treatment methods
and t h e i r sequence. Implement f i r s t t h o s e
t r e a t m e n t s which have t h e g r e a t e s t p o s i t i v e
e f f e c t f o r t h e l e a s t expenditure of money and
e f f o r t . A l o g i c a l concluding s t e p , b u t one
t h a t may be overlooked, c o n s i s t s of following
treatment w i t h a n o r d e r l y program of i n s p e c t i o n
and maintenance (White and Brynildson 1967).
Do n o t f a i l t o consider e i t h e r t h e
f e r t i l i t y of t h e water o r t h e year-round
c a r r y i n g c a p a c i t y o f a stream which otherwise
appears t o have p o t e n t i a l f o r improvement.
H a b i t a t manipulation aimed a t i n c r e a s i n g
cover i n a stream w i l l prove o f l i t t l e v a l u e
i n providing more t r o u t e i t h e r i f production
i s l i m i t e d by a l a c k of n u t r i e n t s o r i f t h e
c a r r y i n g c a p a c i t y of t h e stream i s d r a s t i c a l l y
reduced a t some season, a s by f r e e z i n g i n
w i n t e r o r flooding i n s p r i n g , thereby negating
any e f f e c t s of increased summer production
(White and Brynildson 1967).
P r o t e c t i n g n a t u r a l stream h a b i t a t b e s t
guarantees t h e p e r p e t u a t i o n of n a t i v e t r o u t
populations. The most s i g n i f i c a n t h a b i t a t i n
s m a l l t o moderate-sized streams c o n s i s t s of
undercut banks, which i n t u r n depend on extens i v e v e g e t a t i v e cover of t h e exposed bank
(Wesche 1973). Livestock overgrazing p r e s e n t s
t h e g r e a t e s k t h r e a t t o t h e i n t e g r i t y of headwater s t r e a m h a b i t a t q u a l i t y i n t h e West.
Grazing l i v e s t o c k may d e s t r o y t h e v e g e t a t i v e
cover and cave i n overhanging banks, t h e r e b y
e l i m i n a t i n g t h e most important t r o u t h a b i t a t .
Loss of streambank v e g e t a t i o n l e a d s t o i n c r e a s e d
water temperatures, e r o s i o n and s i l t i n g , elimin a t i o n of spawning s i t e s and r e d u c t i o n of food
s u p p l i e s i n t h e stream, a l l of which d r a s t i c a l l y
degrade t r o u t h a b i t a t .
G u i d e l i n e s have been developed t o minimize
damage t o streams from logging, road b u i l d i n g
and mining o p e r a t i o n s ; i f they a r e conscient i o u s l y followed, good t r o u t p o p u l a t i o n s can
b e maintained i n watersheds s u b j e c t t o t h e s e
uses. The major multiple-use problem y e t t o
b e a d e q u a t e l y t r e a t e d on N a t i o n a l Resource Lands,
however, is t h e impact of l i v e s t o c k grazing on
a q u a t i c h a b i t a t . T h i s problem i s p a r t i c u l a r l y
a c u t e i n a r i d r e g i o n s , where l i v e s t o c k o f t e n
tend t o c o n c e n t r a t e i n r i p a r i a n v e g e t a t i o n along
stream banks. Their impact on t r o u t h a b i t a t
can b e d e v a s t a t i n g .
Although l a c k of r i p a r i a n v e g e t a t i o n , cavedi n banks, e r o s i o n , and s i l t a t i o n a r e r e a d i l y
v i s i b l e r e s u l t s of overgrazing, q u a n t i t a t i v e
d a t a documenting such damage a r e n o t abundant.
Gunderson (1968) r e p o r t e d on t h e f i s h popula-
t i o n s i n comparable grazed and ungrazed s e c t i o n s of Rock Creek, Montana. I n 1964,
126.6 kg/ha of w i l d brown t r o u t occurred i n
t h e grazed s e c t i o n and 167.8 kg/ha i n t h e
ungrazed s e c t i o n . Trout above 30 cm i n
l e n g t h were more than t h r e e times a s abundant
i n t h e ungrazed s e c t i o n . The major h a b i t a t
d i f f e r e n c e s between t h e grazed and t h e ungrazed
s e c t i o n s concerned r i p a r i a n v e g e t a t i o n , bank
s t a b i l i t y and average stream channel depth.
The grazed segment of t h e stream c o n s i s t e d of
a spread-out channel w i t h mainly shallow
r i f f l e a r e a s ; i t lacked deep pools and undercut
banks. By 1970 t h e d i f f e r e n c e s between t h e
two stream segments were even g r e a t e r . Biomass
of w i l d brown t r o u t had d e c l i n e d t o 71 kg/ha
i n t h e grazed s e c t i o n , while i t i n c r e a s e d i n
t h e ungrazed p a r t of t h e s t u d y a r e a t o
238.9 kg/ha.
Interestingly, investigators
found moFe mountain w h i t e f i s h (Prosopium
w i l l i a m s o n i ) i n t h e grazed than i n t h e
ungrazed s e c t i o n . The mountain w h i t e f i s h ,
o f t e n accused of being a s e r i o u s competitor
with t r o u t , more l i k e l y i s j u s t b e t t e r
adapted than t r o u t t o u t i l i z e d i s t u r b e d
h a b i t a t . I n t h e n a t u r a l , ungrazed s e c t i o n of
t h e stream, w h i t e f i s h comprised only 10 percent
of t h e t o t a l f i s h biomass, whereas i n t h e
a l t e r e d grazed h a b i t a t they made up 35 p e r c e n t
of t h e t o t a l f i s h biomass (Marcuson 1970).
The need f o r more p r e c i s e d a t a on t h e
r e l a t i o n s h i p s of l i v e s t o c k d e n s i t y and g r a z i n g
t e c h n i q u e s t o s o i l , c l i m a t e , v e g e t a t i o n and
impacts o n stream environments and f i s h
populations must be considered a s t h e h i g h e s t
r e s e a r c h p r i o r i t y t o provide a sound b a s i s f o r
management d e c i s i o n s which w i l l r e s o l v e t h e
c o n f l i c t s between l i v e s t o c k g r a z i n g and f i s h
habitat quality.
The Intermountain F o r e s t and Range
Experiment S t a t i o n of t h e U. S. F o r e s t S e r v i c e
a t Boise, Idaho has i n i t i a t e d a 10-year s t u d y
t i t l e d "The e f f e c t s of l i v e s t o c k g r a z i n g i n
high mountain meadows on a q u a t i c environments,
streamside environments and f i s h e r i e s , " under
t h e d i r e c t i o n of D r . William P l a t t s , who h a s
s t u d i e d l i v e s t o c k impacts on treams f o r many
he raised
years. I n an e a r l i e r
s i g n i f i c a n t q u e s t i o n s on t h e e f f i c a c y of r e s t r o t a t i o n g r a z i n g management f o r r e s t o r i n g
streambank v e g e t a t i o n and r e h a b i l i t a t i n g
u n s t a b l e banks. P l a t t s observed t h a t , w h i l e
one y e a r of rest may b e s u f f i c i e n t t o r e s t o r e
p a s t u r e g r a s s , it may n o t b e s u f f i c i e n t t i m e
t o e n a b l e p r e v i o u s l y overgrazed streambank
shrubs t o recover.
report^^
g ~ l a t t s W.
, and C. Roundtree. 1972. Bear
Valley Creek, Idaho. Aquatic environment and
f i s h e r y study. USDA F o r e s t S e r v i c e , unpubl.
r e p t . 4E p.
D r . P l a t t s ' r e s e a r c h should provide a
f a c t u a l b a s i s f o r m u l t i p l e u s e management and
more harmonious c o e x i s t e n c e of l i v e s t o c k and
It would be a mistake,
t r o u t populations.
however, t o d e l a y a t t e m p t s t o r e v e r s e stream
h a b i t a t d e t e r i o r a t i o n 1 0 y e a r s w h i l e awaiting
t h e outcome of t h e study. As a s t a r t i n g point,
a recommendation i n t h e Bureau of Land Management's environmental impact statement on
g r a z i n g i n Nevada (USDI Bureau of Land Management 1974) s h o ~ l l db e implemented, namely t h a t
c o s t s f o r p r o t e c t i n g c r i t i c a l environments,
such a s streams and r i p a r i a n v e g e t a t i o n , be
assumed by t h e i n t e r e s t s causing t h e damage.
I f a r a r e t r o u t r e s t o r a t i o n program i s t o be
s u c c e s s f u l where t h e h a b i t a t i s exposed t o
g r a z i n g , a n i n t e g r a l p a r t of t h e program must
c o n s i s t of s t r i c t g r a z i n g c o n t r o l s and watershed p r o t e c t i o n .
For background information on t h e a c t u a l
o r p o t e n t i a l impact of v a r i o u s land-use
p r a c t i c e s on t r o u t streams, s e e : Burns 1970,
Cordone 1956, Cordone and Kelley 1960, E l s e r
1968, Megahan and Kidd 1972, Mullan 1975,
P l a t t s 1974, U.S. F o r e s t S e r v i c e 1975, White
1975, Gibbons and Salo 1973, and Grove 1976.
The U. S. F o r e s t S e r v i c e , Region V I ,
P o r t l a n d , Oregon, i s c u r r e n t l y developing a
f i s h h a b i t a t management p o l i c y which w i l l
i n c l u d e g u i d e l i n e s on:
I.
F i s h h a b i t a t p r o t e c t i o n and r e s t o r a t i o n
A. Timber management and road const r u c t i o n
B
Livestock g r a z i n g
C. Mining
11. F i s h h a b i t a t enhancement
.
The s e c t i o n on timber management and
road c o n s t r u c t i o n has been completed. The
s e c t i o n on l i v e s t o c k g r a z i n g i s i n d r a f t
form, scheduled f o r completion by J u l y 1976.
Other s e c t i o n s have n o t y e t been s t a r t e d .
The Oregon c h a p t e r of t h e American F i s h e r i e s
S o c i e t y passed a r e s o l u t i o n endorsing t h i s
h a b i t a t management p o l i c y and urging i t s
adoption on a nationwide b a s i s (American
F i s h e r i e s S o c i e t y N e w s l e t t e r , March-April,
1975).
POTENTIAL ROLE OF NATIVE TROUT I N
FISHERIES MANAGEMENT
At f i r s t g l a n c e , t h e i d e a of promoting
a n g l i n g f o r a r a r e t r o u t while t h e goal of
t h e program i s t o i n c r e a s e i t s abundance may
appear c o n t r a d i c t o r y . A c t u a l l y , though, t h e
major hope f o r i n c r e a s i n g t h e abundance of a
r a r e trout l i e s i n re-establishing i t i n .
w a t e r s , w i t h i n i t s n a t i v e range, where i t has
been e x t i r p a t e d o r h y b r i d i z e d . I n a l l l i k e l i -
hood, such s i t e s a r e now p u b l i c f i s h i n g w a t e r s .
S t a t e game and f i s h agencies funded, by a n g l e r
l i c e n s e f e e s may be understandably r e l u c t a n t
to c l o s e p u b l i c f i s h i n g w a t e r s i n o r d e r t o
r e - e s t a b l i s l ~ a n a t i v e t r o u t p o p u l a t i o n which
would be f u l l y p r o t e c t e d from a n g l i n g . No
rare o r endangered t r o u t has become s o through
o v e r f i s h i n g ; t h e f e a r t h a t fishermen might
,%terminate a population i s simply n o t based
i n f a c t . Properly p u b l i c i z e d , n a t i v e t r o u t
can be used i n unique, q u a l i t y f i s h e r i e s w i t h
v i r t u a l l y no expense, i f p o p u l a t i o n s reproduce
* a t u r a l l y . Fishermen of t e n p l a c e a h i g h e r
r e c r e a t i o n a l v a l u e on t h e o p p o r t u n i t y t o f i s h
for a n a t i v e t r o u t t h a n f o r a h a t c h e r y t r o u t .
Special regulations f o r native cutthroat
in Idaho test streams i n c l u d e a catch-andr e l e a s e f i s h e r y and a 33-cm minimum s i z e
l i m i t . The abundance, average s i z e and
catch-per-hour of t r o u t i n t h e s t r e a m have
a l l i n c r e a s e d under t h e s e r e g u l a t i o n s ( B a l l
1971, Bjornn and Thurow 1974, Bogander e t a 1
1974). The National Park S e r v i c e i n i t i a t e d
a catch-and-release f i s h e r y on t h e Yellowstone
River i n Yellowstone National Park i n 1973
a f t e r comparisons had shown t h a t 309 c u t t h r o a t
t r o u t sampled i n a c l o s e d s e c t i o n averaged
44.7 cm, a g a i n s t 36.1 cm f o r 378 t r o u t from
the open-fishing a r e a . The catch-per-hour
under t h e s p e c i a l r e g u l a t i o n s i n c r e a s e d by
two- t o f o u r - f o l d over t h e previous f o u r
years; most fishermen were e n t h u s i a s t i c over
the change (Jack Dean, p e r s o n a l communication
to Robert Behnke).
The r e s e a r c h of D r . Ted Bjornn, l e a d e r
of t h e Idaho Cooperative F i s h e r y U n i t , has
provided t h e b e s t evidence o f t h e p o t e n t i a l
of n a t i v e c u t t h r o a t t r o u t t o produce a high
q u a l i t y f i s h e r y under s p e c i a l r e g u l a t i o n s .
In 1971 i n v e s t i g a t o r s attempted t o r e s t o r e
the abundance o f t h e n a t i v e t r o u t i n s e v e r a l
miles o f t h e upper S t . Joe River, Idaho, by
c e s s a t i o n of h a t c h e r y rainbow t r o u t s t o c k i n g
and i n s t i t u t i o n of a n a r t i f i c i a l l u r e f i s h e r y
with a minimum s i z e l i m i t of 33 cm. S t u d i e s
from 1968 t o 1970 had revealed t h a t t h e c u t t h r o a t was s u f f e r i n g heavy a n g l i n g e x p l o i t a t i o n . C u t t h r o a t t r o u t caught by fishermen
averaged only s l i g h t l y over 17.8 cm; only 2.5
percent of t h e population exceeded 25 cm and
only 0 . 1 p e r c e n t exceeded 33 cm. The r e s u l t s
of t h i s management program have proved v e r y
encouraging. Rainbow t r o u t have v i r t u a l l y
disappeared from t h e unstocked a r e a . Cutt h r o a t t r o u t i n c r e a s e d from t h r e e - t o s i x - f o l d
i n abundance i n a r e a s under s p e c i a l r e g u l a t i o n ,
and w i t h o u t s t o c k i n g . Average s i z e of f i s h
caught by a n g l e r s i n c r e a s e d 5 cm i n t h e f i r s t
two y e a r s . The p r o p o r t i o n of f i s h longer
than 25 cm i n c r e a s e d by 1000 p e r c e n t ; t h o s e
over 33 cm i n c r e a s e d by 3000 p e r c e n t . The
number of c u t t h r o a t caught i n c r e a s e d by over
f o u r times--8100 a f t e r i n s t i t u t i o n of s p e c i a l
r e g u l a t i o n s versus 1800 before--and t h e c a t c h per-man-hour i n c r e a s e d by s i x t i m e s , from 0.8
t o 4.8, when comparing d a t a of 1973 w i t h t h a t
of 1968 i n one f i v e - m i l e stream s e c t i o n
(Bjornn 1975). With t h e 33-cm minimum s i z e
l i m i t , a n g l e r s k e p t many fewer c u t t h r o a t , b u t
because of t h e g r e a t l y i n c r e a s e d average s i z e ,
t h e t o t a l weight of c u t t h r o a t t r o u t c r e e l e d
has probably n o t changed g r e a t l y . Angler
response t o t h e n a t i v e c u t t h r o a t f i s h e r y has
g e n e r a l l y been q u i t e s u p p o r t i v e and by 1974,
t h e stream enjoyed t h e same i n t e n s i t y of u s e
t h a t i t had p r i o r t o t h e i n s t i t u t i o n of
s p e c i a l r e g u l a t i o n s , when heavy s t o c k i n g of
c a t c h a b l e rainbow t r o u t supported t h e f i s h e r y .
And s o by p r o t e c t i o n from e x c e s s i v e e x p l o i t a t i o n , a more v a l u a b l e f i s h e r y based s o l e l y on
n a t u r a l r e p r o d u c t i o n of a n a t i v e t r o u t h a s
r e p l a c e d a more expensive c a t c h a b l e t r o u t
f i s h e r y and the v u l n e r a b i l i t y of t h e c u t t h r o a t
t r o u t t o repeated c a t c h i n g h a s r e s u l t e d i n a
g r e a t l y increased catch r a t e .
B a s i c a l l y , t h e d e s i g n of a s p e c i a l regul a t i o n s f i s h e r y assumes t h a t a n a t u r a l t r o u t
population w i l l undergo a " s t o c k p i l i n g " e f f e c t
i f s m a l l e r t r o u t a r e p r o t e c t e d from f i s h i n g
e x p l o i t a t i o n and allowed t o s u r v i v e t o a
l a r g e r s i z e . Most d e t a i l e d s t u d i e s of wild
t r o u t populations i n streams have shown t h a t
s p e c i a l r e g u l a t i o n s designed t o produce more
and l a r g e r t r o u t by r e s t r i c t i n g t h e c a t c h do
n o t work (Allen 1951; Hunt 1966, 1970; L a t t a
1973; Klein 1974). But most of t h e s e s t u d i e s
concerned brook t r o u t ( S a l v e l i n u s f o n t i n a l i s )
and brown t r o u t (Salmo t r u t t a ) . I n t h e s e
s p e c i e s , t h e l a c k of response t o r e s t r i c t e d
c a t c h r e s u l t s from t h e f a c t t h a t h a b i t a t
c h a r a c t e r i s t i c s and food supply govern n a t u r a l
m o r t a l i t y r a t e s and age-size s t r u c t u r e of t h e
populations. T y p i c a l l y , t h e above s t u d i e s
demonstrated t h a t t h e overwhelming m a j o r i t y of
production and biomass--from 70 t o 90 percent-remained t i e d up i n the 0 and I age groups
( t r o u t of sub-catchable s i z e ) and t h a t about
98 p e r c e n t of a l l t r o u t hatched d i e d from
n a t u r a l causes b e f o r e they reached c a t c h a b l e
s i z e , t y p i c a l l y i n age group II+. Under c i r cumstances where a l l age groups compete f o r a
common food supply, and where sub-catchable
t r o u t c o n s t i t u t e t h e bulk of t h e biomass,
a t t e m p t s t o change t h e age and s i z e s t r u c t u r e
of t h e population e i t h e r by p r o t e c t i n g it
from a n g l i n g o r conversely, t o promote a n g l i n g
i n t h e hopes of s t i m u l a t i n g growth i n t h e
f i s h e s t h a t remain, w i l l have l i t t l e e f f e c t
on t h e population a s a whole. This i s because
such a s m a l l segment of t h e t o t a l population
i s exposed t o removal by a n g l i n g , and because
m o r t a l i t y i s compensatory. That i s , reduced
angling mortality r e s u l t s i n increased natural
m o r t a l i t y ; t h e r e f o r e t h e annual s u r v i v a l r a t e
of t r o u t of any year c l a s s remains approximately
t h e same whether t h e f i s h a r e p r o t e c t e d o r
unprotected from a n g l i n g .
Why, t h e n , have t h e c u t t h r o a t t r o u t popul a t i o n s mentioned above a p p a r e n t l y responded
t o s p e c i a l p r o t e c t i v e r e g u l a t i o n s and e x h i b i t e d
a " s t o c k p i l i n g " e f f e c t ? Three major f a c t o r s
a r e l i k e l y involved.
1. I n a l l of t h e s e a r e a s i n v e s t i g a t o r s
s p e c u l a t e , b u t have n o t c o n c l u s i v e l y demons t r a t e d , t h a t t h e spawning and r e a r i n g a r e a s
e x i s t a p a r t from t h e main f i s h i n g a r e a s . This
reduces o r e l i m i n a t e s t h e i n t r a s p e c i f i c comp e t i t i o n between t h e younger, sub -catchable
age groups, and t h e o l d e r , l a r g e r t r o u t .
2. The v u l n e r a b i l i t y of t h e c u t t h r o a t
t r o u t t o angling r e s u l t s i n a higher catchper -man-hour from c u t t h r o a t t r o u t than from
o t h e r s p e c i e s . No one knows how many times a
t r o u t might be caught and r e l e a s e d i n any
given f i s h e r y , b u t Webster and L i t t l e (1947)
r e p o r t e d t h a t 200 rainbow t r o u t stocked i n an
enclosed s e c t i o n o f stream y i e l d e d a c a t c h
(when r e l e a s e d ) of 601 i n 54 days--each t r o u t
was caught a n average of t h r e e times. A l l
s t u d i e s t o d a t e have r e v e a l e d v i r t u a l l y no
(under f i v e p e r c e n t ) m o r t a l i t y i n t r o u t r e - .
l e a s e d from a r t i f i c i a l f l i e s and l u r e s .
3 . I n t h e s t u d i e s on brook t r o u t c i t e d
above, v i r t u a l l y no t r o u t survived t o age
c l a s s I V o r V. I n most c u t t h r o a t t r o u t popul a t i o n s , maximum ages of V I o r V I I appear
r a t h e r commonly. Subsequent s u r v i v a l of o l d e r
age groups r e s u l t s i n a h i g h e r r a t i o of
catchable-size t o smaller s i z e s i n cutthroat
t r o u t p o p u l a t i o n s when compared t o populations
of t y p i c a l l y s h o r t - l i v e d brook t r o u t .
s i z e . V i r t u a l l y a l l f i s h i n a small stream
may d i e of o l d a g e b e f o r e r e a c h i n g a l e n g t h of
25 cm. Most streams holding pure p o p u l a t i o n s
of r a r e , n a t i v e t r o u t a r e t o o small and
remote from c i v i l i z a t i o n t o a t t r a c t more than
negligible f i s h i n g pressure; special angling
r e s t r i c t i o n s a r e n o t j u s t i f i e d under such c i r cums tances
The Province of A l b e r t a , Canada,
h a s i n s t i t u t e d management r e g u l a t i o n s f o r
s m a l l streams c o n t a i n i n g c u t t h r o a t t r o u t which
c o n s i s t s of c l o s i n g t h e streams i n a l t e r n a t e
y e a r s t o a l l o w a buildup of l a r g e r t r o u t
(Radford 1975)
.
.
SUMMARY
S t e p s i n a n a t i v e t r o u t management program may c o n s i s t of:
1. Survey of waters t o c o l l e c t specimens
from suspected pure populations and t o l o c a t e
potential s i t e s f o r re-introduction.
2. Taxonomic study s f c o l l e c t i o n s t o
i d e n t i f y pure populations.
3 . P r o t e c t i o n and p o s s i b l e improvelnent
of h a b i t a t .
4 . I n t r o d u c t i o n i n t o b a r r e n o r chemically
t r e a t e d w a t e r s i s o l a t e d by some b a r r i e r a g a i n s t
contamination by non-native t r o u t s .
5. Establishment of s p e c i a l r e g u l a t i o n
f i s h e r i e s where a p p l i c a b l e .
1.
A h i g h e r annual s u r v i v a l of o l d e r age
groups (age I1 and o l d e r ) i n d i c a t e s a d e c r e a s e
i n n a t u r a l m o r t a l i t y . Where a n g l i n g m o r t a l i t y
becomes high i n such a s i t u a t i o n , i t may
exceed n a t u r a l m o r t a l i t y and depress t h e popul a t i o n below t h e c a r r y i n g c a p a c i t y of t h e
environment. Temporary p r o t e c t i o n from a n g l i n g ,
o r a lowering of t h e c r e e l l i m i ' t i n such
i n s t a n c e s , would r e s u l t i n h i g h e r annual s u r v i v a l and a n i n c r e a s e i n numbers.
( t r o u t taxonomy; e v a l u a t i o n of r e l a t i v e
p u r i t y of populations; r e s t o r a t i o n
projects)
2.
Stream m o d i f i c a t i o n t o produce more s h e l t e r
and deeper w a t e r can i n c r e a s e the p r o p o r t i o n of
o l d e r t o younger t r o u t , food u t i l i z a t i o n , b i o mass and a n g l e r c a t c h . Hunt (1969) demonstrated
the e f f i c a c y of stream m o d i f i c a t i o n i n Lawrence
Creek, Wisconsin.
Generally, s p e c i a l r e g u l a t i o n s work b e s t
f o r a trophy f i s h e r y and r e q u i r e moderate t o
l a r g e r i v e r s o r l a k e s where food and space
permit r a p i d growth and a t t a i n m e n t o f a l a r g e
Robert Behnke
Dept. of F i s h e r y and W i l d l i f e Biology
Colorado S t a t e U n i v e r s i t y
F o r t C o l l i n s , CO 80521
A l l e n Binns
H a b i t a t Management B i o l o g i s t
Wyoming Game and F i s h Department
Box 342
Lander, WY 52520
(state-federal cooperative r e s t o r a t i o n
p r o j e c t s i n c l u d i n g surveys, h a b i t a t
improvement, c o n s t r u c t i o n of b a r r i e r s )
3.
Ted Bjornn, Leader
Idaho Cooperative F i s h e r y U n i t
College of F o r e s t r y and W i l d l i f e Management
U n i v e r s i t y of Idaho
Moscow, I D 83843
(experience w i t h s p e c i a l r e g u l a t i o n s t o
e s t a b l i s h f i s h e r i e s based on n a t i v e t r o u t )
4.
11. James Mullan
U. S . Fish and W i l d l i f e S e r v i c e
V e r n a l , UT
Robert Borovicka
Bureau of Land Management
729 N. E. Oregon S t r e e t
P o r t l a n d , OR 97208
( r e s t o r a t i o n p r o j e c t s ? e x t e r m i n a t i o n of
non-native f i s h e s , land-use impacts)
12.
(state-federal cooperative projects t o
improve t r o u t h a b i t a t by dams and o t h e r
s t r u c t u r e s and by p r o t e c t i o n from
overgrazing)
5.
J a c k Dean
F i s h Management B i o l o g i s t
U. S. F i s h and W i l d l i f e S e r v i c e
Yellowstone N a t i o n a l Park, WY 82190
(special regulation fisheries, native
t r o u t management)
6.
Paul Jeppson
Idaho F i s h and Game Department
600 S. Walnut, Box 25
Boise, I D 83707
(state-federal cooperative projects t o
improve t r o u t h a b i t a t by dams and o t h e r
s t r u c t u r e s , and p r o t e c t i o n from o v e r grazing)
7.
Douglas J e s t e r
Department of Range and W i l d l i f e
New Mexico S t a t e U n i v e r s i t y
Las Cruces, NM 88003
( r a r e t r o u t r e s t o r a t i o n p r o j e c t s , stream
improvements )
8.
James Johnson
U.S. F i s h and W i l d l i f e S e r v i c e
Albuquerque, New Mexico
( l i v e s t o c k g r a z i n g impacts on s t r e a m s )
9.
J. R. Kimball
U. S. F o r e s t S e r v i c e
4438 F e d e r a l B u i l d i n g
125 S. S t a t e S t r e e t
S a l t Lake C i t y , UT 84111
(improvement of t r o u t h a b i t a t through cont r o l of o v e r g r a z i n g ; improvement d e v i c e s )
10.
Henry McKirdy
U. S F o r e s t S e r v i c e
Federal Building
Missoula, MT 59801
.
(stream improvement d e v i c e s , n a t i v e t r o u t
management)
,
William P l a t t s
U. S . F o r e s t S e r v i c e
Boise Research Work U n i t
316 E. Myrtle S t r e e t
Boise, I D 83706
(land-use impacts on streams and a q u a t i c
life)
13.
Max R o l l e f s o n
Wyoming Department of Game and F i s h
Box 483
Jackson, WY 63001
( h a b i t a t improvement t o i n c r e a s e spawning
and n u r s e r y a r e a s f o r n a t i v e c u t t h r o a t
trout)
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B a l l , K.
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1973. An annotated bibliography of t h e
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United S t a t e s and Canada. USDA For. Serv.
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Northwest For. and Range Exp. S t n . , Portl a n d , Ore.
G r i f f i t h , J. S.
1972. Comparative behavior and h a b i t a t
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f o n t i n a l i s ) and c u t t h r o a t t r o u t (Salmo
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J o u r . Fish. Res. Bd. Canada '29:265-273.
1974. U t i l i z a t i o n of i n v e r t e b r a t e d r i f t by
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Grove, A. (ed.)
1976. Stream management of salmonids.
Supplement t o Trout Magazine, 17(1):31 p.
Gunderson, D. R.
1968. Floodplain use r e l a t e d t o stream
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Herrington, R. B. and D. K. Dunham.
1967. A technique f o r sampling general f i s h
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F o r e s t Service, Intermountain For. and
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Hogander, G., T. C. Bjornn and S. P e t t i t .
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17 p.
Hunt, R. L.
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brook t r o u t i n Lawrence Creek, Wisconsin.
Wisconsin Conserv. Dept., Tech. Bull.
35:52 p.
1969. E f f e c t s of h a b i t a t a l t e r a t i o n on prod u c t i o n , s t a n d i n g crops and y i e l d of brook
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P S Larkin (ed ) , Symposium on salmon
H. R. McMillan
and t r o u t i n streams
Lectures i n F i s h e r i e s , Univ. of B r i t i s h
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. .
1972. P e r s i s t e n c e of headwater check dams
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.
In
.
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~ ~ ~ k s Bonnie
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1975. Wild t r o u t management. T r o u t
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1974. S p e c i a l r e g u l a t i o n s and e l i m i n a t i o n
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COLORADO RIVER CUTTHROAT
Salmo c l a r k i p l e u r i t i c u s
-TYPICAL MERISTIC CHARACTERS
Scale counts
lateral series
(two rows above l a t e r a l
line)
and above l a t e r a l l i n e
( o r i g i n of d o r s a l f i n
t o l a t e r a l line)
Vertebrae
170-20M38-48
60-63
(mean 61-62)
Gillrakers
17-21
Pyloric caecae
25-45
(mean 30-40)
Basibranchial t e e t h
1-20
d a t a from Behzke
-/-~axonomic
1975), Wernsman (1973)-/
(1974,
SPECIES DESCRIPTION
No m e r i s t i c c h a r a c t e r s unique t o g. 2.
p l e u r i t i c u s e x i s t which can s e r v e t o a u t h o r i t a t i v e l y a s s i g n a specimen to. t h i s taxon.
Hybridization r e s u l t i n g from t h e i n t r o d u c t i o n
of rainbow t r o u t and o t h e r subspecies of
c u t t h r o a t t r o u t i n t o t h e Colorado River b a s i n
f u r t h e r complicates t h e r e c o g n i t i o n of pure
Populations. I n g e n e r a l , t h e mean v a l u e s o f
at l e a s t t e n specimens a r e needed t o determine
the degree of p u r i t y of a p o p u l a t i o n i n
question.
--
Salmo c l a r k i p l e u r i t i c u s , n a t i v e t o t h e
upper Colorado River b a s i n i s , w i t h t h e greenback t r o u t of t h e Arkansas and South P l a t t e
drainages on t h e o t h e r s i d e o f t h e C o n t i n e n t a l
Divide, among t h e most c o l o r f u l o f a l l t h e
recognized forms of c u t t h r o a t t r o u t . The
highly variable coloration consists typically
of a poorly d e f i n e d pink o r r e d band a l o n g t h e
b r a s s y yellow s i d e s . The v e n t r a l r e g i o n may
b e s u f f u s e d w i t h crimson i n mature males.
Character v a r i a b i l i t y between populations
of d i f f e r i n g geographical a r e a s e x i s t s due t o
long p h y s i c a l i s o l a t i o n of major h a b i t a t a r e a s
i n t h e Colorado and Green River b a s i n s . For
example, c u t t h r o a t t r o u t s n a t i v e t o t h e upper
Green River b a s i n (La Barge Creek, n o r t h ) d i s p l a y s m a l l t o moderate-sized s p o t s , t y p i c a l l y
s m a l l e r t h a n t h e p u p i l of t h e eye, concentrated
mainly on t h e caudal peduncle and, a n t e r i o r l y ,
above the l a t e r a l l i n e . S i g n i f i c a n t l y l a r g e r
s p o t s occur on c u t t h r o a t s from t h e L i t t l e
Snake River d r a i n a g e (a t r i b u t a r y t o t h e Yampa
R i v e r ) ; t h e s e may approach a s i z e more t y p i c a l
of t h e greenback t r o u t . A l l degrees of i n t e r mediacy i n s p o t t i n g occur, b u t one should
expect pure o r e s s e n t i a l l y pure populations
t o s h a r e a h i g h degree of u n i f o r m i t y w i t h i n
any geographical a r e a where they have had t h e
o p p o r t u n i t y t o f r e e l y intercommunicate. Baxter
and Simon (1970) and Baxter (1972) p r e s e n t
photographs of t h e l a r g e - s p o t t e d form of t h e
Colorado River c u t t h r o a t , probably taken of
specimens from t h e L i t t l e Snake River d r a i n a g e
of Wyoming. The i l l u s t r a t i o n i n t h i s r e p o r t i s
based on a specimen from Rock Creek, Wyoming,
Map 1.
Indigenous distribution of Salrno clarki pleuriticus.
and & a r a c t e r i z e s the s p o t t i n g p a t t e r n of t h e
native t r o u t of t h e upper Green R i v e r system.
DISTRIBUTION
The o r i g i n a l d i s t r i b u t i o n of 2. 5.
l e u r i t i c u s extended from t h e headwaters of
fhe Colorado River b a s i n downstream t o t h e
Dirty Devil River, Utah, on t h e west and t o
the San Juan drainage of Colorado, New Mexico
and Arizona on t h e e a s t . But due t o t h e
and t u r b i d i t y of t h e w a t e r , most a r e a s
of the Colorado and Green Rivers d i d n o t comp-ise t r o u t h a b i t a t u n t i l a f t e r t h e c o n s t r u c tion of mainstream dams (Behnke 1974, Wernsman
1973). R e s u l t a n t i s o l a t i o n of the v a r i o u s
t r i b u t a r i e s caused much of t h e v a r i a b i l i t y
inherent i n &. 5. p l e u r i t i c u s .
Only two populations of t h e many examined
appear t o be wholly pure. They occur i n an
isolated s e c t i o n of Rock Creek, t r i b u t a r y t o
La Barge Creek, and i n North Beaver Creek, an
isolated t r i b u t a r y i n t h e Piney Creek d r a i n a g e ;
both populations e x i s t i n S u b l e t t e County,
Wyoming. A p o s s i b l y pure p o p u l a t i o n discovered
i n 1970 and d e s c r i b e d by Wernsman (1973) from
the very headwaters of t h e Colorado River i n
Rocky Mountain National Park can probably now
be considered e x t i n c t f o r a l l p r a c t i c a l purposes. Extensive sampling of t h e a r e a i n 1974
and 1975 turned up o n l y t h r e e c u t t h r o a t t r o u t
in a m u l t i t u d e of brook t r o u t .
Numerous p o p u l a t i o n s , however, remain
phenotypically good r e p r e s e n t a t i v e s of S,
p l e u r i t i c u s even though they show some evidence
of h y b r i d i z a t i o n . Although c o l o r a t i o n and
spotting p a t t e r n s remain t y p i c a l , c l o s e r
examination r e v e a l s a s l i g h t hybrid i n f l u e n c e
in the form of t h e absence of b a s i b r a n c h i a l
teeth, a g r e a t e r range of v a r i a b i l i t y i n
meristic c h a r a c t e r s , and a s h i f t i n t h e mean
values of some c h a r a c t e r s . Such p o p u l a t i o n s ,
while n o t wholly pure, s t i l l m e r i t s p e c i a l
recognition i n management and land u s e d e c i s i o n s
a f f e c t i n g t h e i r well-being (Belmke 1974, 1975,
1976; Wernsman 1973).
c.
STATUS AND POPULATION TReND
Although c u t t h r o a t t r o u t e x i s t i n good
numbers i n small lakes and streams i n t h e
Colorado River b a s i n of Colorado, Utah, and
Wyoming, p u r e populations of 2.
pleuriticus
are indeed r a r e throughout i t s range.
c.
H a b i t a t a l t e r a t i o n and t h e i n t r o d u c t i o n
non-native t r o u t s have caused t h e p r e c i p i t o u s
decline of t h e Colorado River c u t t h r o a t . Brown
trout and rainbow t r o u t have completely r e PLaced &. c. p l e u r i t i c u s i n l a r g e r r i v e r s , and
Of
brook t r o u t have f r e q u e n t l y d i s p l a c e d i t i n
s m a l l e r t r i b u t a r i e s , but t h e major f a c t o r pushi n g pure populations of t h e Colorado River c u t t h r o a t towards e x t i n c t i o n has been h y b r i d i z a t i o n
with rainbow t r o u t and non-native c u t t h r o a t
t r o u t used i n s t o c k i n g programs i n Colorado,
Utah, and Wyoming.
M i l l e r (1972) included S. 5. p l e u r i t i c u s
i n h i s l i s t of t h r e a t e n e d f r e s h w a t e r f i s h e s of
t h e United S t a t e s . The Utah Fish Committee of
t h e American F i s h e r i e s S o c i e t y ' s Bonneville
Chapter l i s t s it a s endangered (Holden e t a l .
1974). The Colorado D i v i s i o n of W i l d l i f e
l i s t s 5. 2. p l e u r i t i c u s a s t h r e a t e n e d .
W e recommend t h a t 5. & p l e u r i t i c u s b e
recognized a s t h r e a t e n e d by t h e U.S. Department of I n t e r i o r .
LIFE HISTORY
No published l i f e h i s t o r y d a t a e x i s t f o r
t h i s t r o u t s a v e t h a t concerning t h e l a c u s t r i n e s p e c i a l i z e d and s l i g h t l y hybridized p o p u l a t i o n
of T r a p p e r ' s Lake, Colorado (Snyder and Tanner
1960, Drummond 1966), which h a s l i t t l e v a l u e i n
r e l a t i o n t o knowledge of t h e l i f e h i s t o r y and
ecology of 2. 5 p l e u r i t i c u s throughout i t s
range. A l l of t h e g e n e r a l i n f o r m a t i o n concerning
l i f e h i s t o r y and ecology appearing i n Chapter I
can be a p p l i e d t o &. 2. p l e u r i t i c u s .
A s i g n i f i c a n t a t t r i b u t e of t h e Colorado
River c u t t h r o a t i n t h e Green River d r a i n a g e of
Wyoming l i e s i n t h e f a c t t h a t s e v e r a l "good"
r e p r e s e n t a t i v e populations of t h i s subspecies
e x i s t i n s e v e r a l badly degraded streams of t h e
f o o t h i l l s r e g i o n . Many of t h e s e streams might
be c h a r a c t e r i z e d a s submarginal t r o u t h a b i t a t ,
s i n c e they have s u f f e r e d from t h e e f f e c t s of
overgrazing and i r r i g a t i o n dewatering, which
have l e d i n t u r n t o e r o s i o n , warm temperatures
and t u r b i d i t y . I n s p i t e of h a b i t a t d e g r a d a t i o n
and t h e i n t r o d u c t i o n of rainbow t r o u t and nonn a t i v e forms of c u t t h r o a t t r o u t , t h e n a t i v e
populations have r e s i s t e d h y b r i d i z a t i o n and
displacement t o a s u r p r i s i n g degree. The o n l y
e x p l a n a t i o n appears t o be t h a t t h e s e l o c a l popu l a t i o n s a r e hardy and adapted t o t h e p r e s e n t
c o n d i t i o n s t o such a n e x t e n t t h a t n a t u r a l
s e l e c t i o n s t r o n g l y favors maintenance of t h e
n a t i v e genotype. These factors--environmental
d e g r a d a t i o n and t h e i n t r o d u c t i o n of non-native
trouts--under which many predominantly 2. 5
p l e u r i t i c u s s t i l l s u r v i v e , have almost i n v a r i a b l y caused t h e e x t e r m i n a t i o n of o t h e r subs p e c i e s of i n t e r i o r c u t t h r o a t t r o u t (Behnke
1975).
HABITAT K3QUIREMENTS Ah9 LIMITING FACTORS
A l l western t r o u t s of the genus Salmo
possess e s s e n t i a l l y s i m i l a r h a b i t a t requirements
A broad-based e c o l o g i c a l v a r i a b i l i t y allows
populations t o t h r i v e i n small streams, l a r g e
r i v e r s or lakes. W i l e several lakes i n the
Colorado River b a s i n o r i g i n a l l y contained
S. 2. p l e u r i t i c u s whose b a s i c l i f e h i s t o r y
a t t r i b u t e s may have d i f f e r e d s l i g h t l y from
stream o r r i v e r p o p u l a t i o n s , t h e b a s i c r e q u i r e ments i n terms of temperature, oxygen, and
s u b s t r a t e f o r r e p r o d u c t i o n and s u r v i v a l a r e
q u i t e s i m i l a r f o r a l l 5. 2. p l e u r i t i c u s
Any
f a c t o r s l e a d i n g t o l o s s of cover, s i l t a t i o n
and warming of t h e w a t e r s w i l l have d e t r i m e n t a l
impacts on c u t t h r o a t t r o u t . But t h e most
s i g n i f i c a n t f a c t o r limiting the perpetuation
of pure p o p u l a t i o n s remains t h e h y b r i d i z a t i o n
r e s u l t i n g from t h e i n t r o d u c t i o n of rainbow
t r o u t and e x o t i c subspecies of c u t t h r o a t t r o u t .
-
.
PROTECTIVE MEASURES
The Wyoming Game and F i s h Department has
h i r e d a h a b i t a t management b i o l o g i s t , D r .
A l l e n Binns, t o d i r e c t p r o t e c t i o n , enhancement
and r e s t o r a t i o n of n a t i v e t r o u t populations i n
Wyoming. The Department i s conducting s e v e r a l
p r o j e c t s i n t h e Green River d r a i n a g e , some i n
c o o p e r a t i o n w i t h t h e Bureau of Land Management
and t h e U. S. F o r e s t S e r v i c e . P r o j e c t s i n c l u d e
stream improvement, spawning enhancement,
b a r r i e r c o n s t r u c t i o n , t r a n s p l a n t i n g and e x p e r i mental propagation. D r . Binns r e p o r t e d on
t h i s work a t t h e Colorado-Wyoming Chapter of
t h e American F i s h e r i e s S o c i e t y meeting i n
A p r i l 1975. Robert Behnke has examined s e v e r a l
hundred specimens and has evaluated t h e r e l a t i v e p u r i t y of many samples of Green River
b a s i n c u t t h r o a t t r o u t , c o l l e c t e d during surveys
made by Wyoming personnel (Behnke 1975).
The Bureau of Land Management, Colorado
S t a t e O f f i c e , has fenced a s e c t i o n of Northwater
Creek, a t r i b u t a r y t o Parachute Creek i n the
o i l s h a l e country of northwest Colorado, t o
p r o t e c t a good r e p r e s e n t a t i v e population o f
S . 2. p l e u r i t i c u s from l i v e s t o c k overgrazing.
G o t h e r v i r t u a l l y pure population of 5. 2.
p l e u r i t i c u s occurs i n Cunningham Creek, which
has been a f f e c t e d by d i v e r s i o n s from t h e
Frying Pan-Ar-kansas P r o j e c t of t h e Bureau of
Reclamation. A c o o p e r a t i v e agreement between
t h e Colorado D i v i s i o n of W i l d l i f e and t h e
Bureau of Reclamation is designed t o m i t i g a t e
t h e dewatering impact of t h e p r o j e c t on t h e
t r o u t population.
Another Bureau of Reclamation p r o j e c t ,
t h e Meek's Cabin Reservoir i n t h e Utah-Wyoming
border a r e a , flooded a n a t u r a l b a r r i e r on t h e
L i t t l e West Fork of t h e Black Fork River and
an a r t i f i c i a l b a r r i e r was c o n s t r u c t e d t o prev e n t h y b r i d i z a t i o n of t h e e s s e n t i a l l y pure
S. 2. p l e u r i t i c u s population w i t h rainbow
trout.
-
According t o 1973 and 1974 annual r e p o r t s
on f i s h e r i e s management i n Rocky Mountain
National Park, prepared by James Mullan of
t h e U. S. F i s h and W i l d l i f e S e r v i c e , Vernal,
Utah, plans e x i s t f o r r e i n t r o d u c t i o n of g. 5.
p l e u r i t i c u s i n t o t h e Colorado River d r a i n a g e
i n $he Park.
RECOMMENDATIONS
Although t h e o r i g i n a l range of 5. 2.
p l e u r i t i c u s covers a l a r g e a r e a i n Wyoming,
Utah, Colorado and New Mexico, only i n t h e
Green River b a s i n of Wyoming has a concerted
e f f o r t been made t o survey w a t e r s f o r n a t i v e
t r o u t populations, evaluate t h e i r r e l a t i v e
p u r i t y and i n s t i t u t e p r o t e c t i v e and r , e s t o r a t i v e
measures. The e f f o r t s of t h e Wyoming' F i s h and
Game Department should be emulated i n Colorado,
Utah and New Mexico i n o r d e r t o a u t h o r i t a t i v e l y
determine i t s s t a t u s and t o develop programs
t o p r o t e c t and p e r p e t u a t e t h i s t r o u t throughout
i t s range.
Populations which a r e v i r t u a l l y pure and
judged t o be good taxonomic r e p r e s e n t a t i v e s
should be given s p e c i a l r e c o g n i t i o n i n r e l a t i o n
t o h a b i t a t p r o t e c t i o n o r enhancement p r o j e c t s .
H a b i t a t improvement and t r a n s p l a n t s i n t o
b a r r e n o r chemically t r e a t e d streams and lakes
can e f f e c t t h e i n c r e a s e d abundance of pure
populations. H a b i t a t managers should consider
s p e c i a l r e g u l a t i o n f i s h e r i e s programs both t o
o f f e r anglers the opportunity t o f i s h f o r a
r a r e and b e a u t i f u l n a t i v e t r o u t and t o generate
i n t e r e s t and support among the p u b l i c f o r
r e s t o r a t i o n programs.
These recommendations assume added s i g n i f i c a n c e i n view of t h e f a c t t h a t g. 2.
p l e u r i t i c u s i s n a t i v e t o a l l of t h e o i l s h a l e
r e g i o n and much of t h e p o t e n t i a l c o a l s t r i p
mine a r e a s of Colorado, Utah and Wyoming. A
1975 r e p o r t prepared f o r t h e O f f i c e of Biologic a l S e r v i c e s of t h e U. S. Fish and W i l d l i f e
S e r v i c e (Thorne E c o l o g i c a l I n s t i t u t e , 1975),
gave t h e h i g h e s t r e s e a r c h p r i o r i t y t o t h r e a t ened and endangered s p e c i e s .
AUTHORITIES
1975. Report on r e c e n t c o l l e c t i o n s of c u t t h r o a t t r o u t from the Green River basin,
Wyoming. Wyoming Game and Fish Department.
12 p. (mimeo)
1 , Robert Behnke
Dept. of Fishery and W i l d l i f e Biology
Colorado S t a t e University
F o r t C o l l i n s , CO 80521
1976. Report on c o l l e c t i o n s of c u t t h r o a t
t r o u t from Parachute Creek drainage,
G a r f i e l d County, Colorado. Prepared f o r
BLM, Grand Junction. 7 p.
(systematic i n v e s t i g a t i o n s , e v a l u a t i o n of
purity, restoration projects)
2.
Allen Binns
Wyoming Game and Fish Department
Box 342
Lander, WY 82520
Drummond, R. A.
1966. Reproduction and h a r v e s t of c u t t h r o a t
t r o u t a t Trapper's Lake, Colorado. Colorado Department of Game, Fish and Parks,
Spec. Rept. 10:26 p.
( p r o t e c t i v e and r e s t o r a t i o n p r o j e c t s i n
the Green River basin)
3.
Holden, P. B . , W. White, G. Somerville, D. Duff,
R. Gervais and S. Gloss.
1974. Threatened f i s h of Utah. Proc. Utah
Acad. Science, A r t s and L e t t e r s 51 ( p t . 2):
46-65.
James Johnson
U . S . F i s h and W i l d l i f e Service
Albuquerque, New Mexico
(formerly i n charge of BLM e f f o r t s i n
Colorado t o p r o t e c t threatened and
endangered f i s h e s )
4.
M i l l e r , R. R.
1972. Threatened freshwater f i s h e s of t h e
United S t a t e s . Trans. Am. Fish. Soc.
lOl(2): 239-252.
James Mullan
U. S. Fish and W i l d l i f e S e r v i c e
Vernal, UT
Snyder, G. R. and H. A. Tanner.
1960. Cutthroat t r o u t reproduction i n t h e
i n l e t s t o Trapper's Lake. Colorado Dept.
of Game, Fish and Parks, Tech. Bull. 7:
86 p.
(general t r o u t management and h a b i t a t
requirements i n Xocky Mountain region
and f i s h e r i e s management a c t i v i t i e s i n
Rocky Mountain National Park)
Thorne Ecological I n s t i t u t e .
1975. W i l d l i f e and o i l s h a l e , a problem
a n a l y s i s and research program. U. S .
F i s h and W i l d l i f e Service, O f f i c e of
B i o l o g i c a l Services. Vol. I. 112 p.
REFERENCES
Baxter, G. T.
1972. The c u t t h r o a t , a f i s h with n a t i v e
r o o t s . Wyo. Wildl. 36 (5): 16-19.
Wernsman, G.
1973. The n a t i v e t r o u t s of Colorado. M.S.
Thesis, Colorado S t . Univ., Ft. Collins.
57 p *
and J. R. Simon.
1970. Wyoming f i s h e s . Wyoming Game and
Fish D&. ,- ~ u l l .4. 168
.-
Behnke, R. J.
1970. Rare and endangered s p e c i e s r e p o r t :
the n a t i v e c u t t h r o a t t r o u t of t h e ColoradoGreen River basin, Salmo c l a r k i p l e u r i t i c u s
Colorado Cooperative Fishery Unit. 7 p.
(mimeo)
-
1974. S t a t u s r e p o r t : S a h o c l a r k i
p l e u r i t i c u s . Prepared f o r Region 11,
U. S. Fish and W i l d l i f e Service. Albuauerwe, N.M. 6 p. (mimeo)
.
NEBRASKA
WYOMING
Laramie
NEW MEXICO
0
I
25
50
I
75
I
Kilometers
Map 2.
Indigenous distribution of Salmo clarki stomias.
GREENBACK CUTTHROAT
Salmo c l a r k i stomias
--TYPICAL MERISTIC CHARACTERS
Scale counts
l a t e r a l series
(two rows above l a t e r a l
line)
and above l a t e r a l l i n e
( o r i g i n of d o r s a l f i n
to lateral line)
Vertebrae
175-220+
(mean v a l u e s
185-216)
42-60
(mean v a l u e s
45-55)
59-63
(mean v a l u e s
60-62)
Pyloric caecae
(mean v a l u e s
29-35)
Basibranchial t e e t h
Present, but
highly variable
SPECIES DESCRIPTION
Taxonomic c r i t e r i a f o r 5. c. stomias
remain t e n t a t i v e due t o t h e extreme r a r e n e s s
of pure populations and t o t h e s c a r c i t y of
a n c i e n t museum specimens. Even s o , s c a l e
counts made from a v a i l a b l e specimens c o n s i s t e n t l y e x h i b i t t h e h i g h e s t v a l u e s o f any c u t t h r o a t t r o u t , o r any t r o u t i n t h e genus
It may b e assumed t h a t extremely h i g h s c a l e
counts a r e c h a r a c t e r i s t i c of pure populations
of 2. 5. stomias, w i t h some s u g g e s t i o n t h a t
t h o s e p o p u l a t i o n s n a t i v e t o t h e South P l a t t e
b a s i n may show s l i g h t l y h i g h e r counts than
those n a t i v e t o t h e Arkansas d r a i n a g e . The
greenback c u t t h r o a t d i s p l a y s t y p i c a l l y lower
numbers of p y l o r i c caecae and v e r t e b r a e than
most o t h e r subspecies of S. c l a r k i , b u t much
o v e r l a p occurs i n t h e s e c h a r a c t e r s .
u.
---
Salmo c l a r k i stomias undoubtedly d e r i v e d
v i a a n a n c i e n t headwater t r a n s f e r from w a t e r s
of t h e Colorado River b a s i n t o t h e South
P l a t t e River d r a i n a g e , and f o r t h i s r e a s o n
s h a r e s many s i m i l a r i t i e s w i t h t h e Colorado
River c u t t h r o a t , &.
p l e u r i t i c u s . The s t r i k i n g s p o t t i n g p a t t e r n and i n t e n s e c o l o r a t i o n
which c a n develop i n mature f i s h i s t h e most
d i a g n o s t i c f i e l d c h a r a c t e r of t h e greenback
t r o u t . &. 2. stomias t y p i c a l l y d i s p l a y s t h e
l a r g e s t and most pronounced s p o t s of any c u t t h r o a t t r o u t . Round t o oblong i n shape, they
appear concentrated p o s t e r i o r l y on t h e caudal
peduncle a r e a . Coloration, s i m i l a r t o 2. 5.
p l e u r i t i c u s , tends toward blood-red over t h e
lower s i d e s and v e n t r a l r e g i o n , e s p e c i a l l y i n
c.
/-~axonomic
-
d a t a from Bebgke (1973,
1976), Wernsman (1973)J
mature males. Although a genetic b a s i s e x i s t s
t o express c h a r a c t e r i s t i c c o l o r p a t t e r n s , t h e
a c t u a l m a n i f e s t a t i o n of c o l o r i n t e n s i t y and
p a t t e r n depends a l s o on age, s e x and d i e t .
For example, a l a k e environment with c r u s t a ceans a v a i l a b l e f o r food w i l l induce a more
i n t e n s e expression of c o l o r than a small
s tream environment.
LIFE HISTORY
L i t t l e specific l i f e history data e x i s t
f o r t h e greenback c u t t h r o a t . While S_. c.
stomias appears t o l a c k t'he r e s i l i e n c y and
a d a p t a b i l i t y which i t needs t o c o e x i s t w i t h
introduced t r o u t s , t h e mechanisms by which i t
i s displaced i n r e l a t i o n t o spawning behavior,
temperature, h a b i t a t and food preferences, o r
o t h e r f a c t o r s , remain unknown.
DISTRIBUTION
The o r i g i n a l distribution of 2. c. stomias
included t h e headwaters of t h e South P l a t t and
Arkansas River b a s i n s i n Colorado and a small
a r e a i n s o u t h e a s t e r n Wyoming, but permanent
t r o u t h a b i t a t d i d n o t extend much beyond t h e
f o o t h i l l s region. The advent of white man's
c l v l l i z a t i o n r a p i d l y pushed t h e greenback t r o u t
back t o headwater a r e a s , r e p l a c i n g it i n t h e
l a r g e r streams w i t h brown t r o u t , and w i t h brook
t r o u t i n smaller t r i b u t a r i e s . Further introduct i o n s i n t o headwater streams and l a k e s displaced
o r hybridized t h e n a t i v e greenback t r o u t t o t h e
p o i n t of v i r t u a l e x t i n c t i o n .
STATUS AND POPULATION TREND
When t h e white man came t o Colorado, t h e
greenback t r o u t was the only game f i s h found
i n t h e Arkansas and South P l a t t e r i v e r systems
of t h e s t a t e . Rapid development brought about
i r r i g a t i o n d i v e r s i o n s and stream dewatering,
mining p o l l u t i o n , logging, grazing, widespread
i n t r o d u c t i o n of non-native t r o u t s , and caused
a p r e c i p i t o u s d e c l i n e of n a t i v e t r o u t populat i o n s . Greene (1937) believed they were
e x t i n c t . Although c u t t h r o a t t r o u t remain
common i n h i g h e l e v a t i o n l a k e s and streams of
t h e South P l a t t e and Arkansas River b a s i n s ,
v i r t u a l l y none of t h e populations s o f a r
examined resemble t h e n a t i v e greenback t r o u t
(Wernsman 1973) b u t i n s t e a d have r e s u l t e d
from i n t r o d u c t i o n s of various non-native r a c e s
and crosses of c u t t h r o a t t r o u t , u s u a l l y with
t r a c e s of rainbow t r o u t h y b r i d i z a t i o n . This
c i r c u m s t a n t i a l evidence suggests t h a t t h e
greenback t r o u t may be t h e most vulnerable of
a l l t h e western t r o u t s t o e x t i n c t i o n .
Analysis of a l l specimens examined t o
1970 suggested only two pure populations.
One of t h e s e occurs i n Como Creek, a n i s o l a t e d
t r i b u t a r y t o North Boulder Creek, Boulder
County, Colorado; t h e o t h e r is found i n the
very headwaters of t h e South Poudre River
above a b a r r i e r f a l l s i n Larimer County,
Colorado. Due t o i t s extreme r a r e n e s s , 2. 2.
stomias has been l i s t e d a s endangered by t h e
U. S. Department of t h e I n t e r i o r . .
A more complete d i s c u s s i o n on t h e s t a t u s
of t h e green back c u t t h r o a t was w r i t t e n by
Behnke (1976).
Some l i f e h i s t o r y d a t a have been collected
on two s l i g h t l y hybridized populations which
can be considered "goodn,representative greenBulkley (1959) gatherel
back t r o u t populations
information on age and growth, food h a b i t s and
movement of t h e greenback population i n t h e
headwaters of t h e Big Thompson River i n Forest
Cqyon of Rocky Mountain National Park. Nelson
(1972) s t u d i e d t h e unexploited population of
I s l a n d Lake, a r e s e r v o i r i n t h e C i t y o f Boulder
watershed, and provided d a t a on age, growth
and fecundity. Jordan (1891) and Juday (1907)
made observations on s i z e and food h a b i t s of
greenback t r o u t i n Twin Lakes, Colorado. None
o f these r e p o r t s i n d f c a t e any unique l i f e h i s & stomias. That i s ,
t o r y a t t r i b u t e s of
t h e d a t a and observations a r e t y p i c a l of any
t r o u t l i v i n g under s i m i l a r circumstances and
o f f e r l i t t l e i n ~ i g h ti n t o whatever s u b t l e
d i f f e r e n c e s i n ecoLogy e x i s t f o r t h e greenback
t r o u t which make it s o vulnerable t o d i s p l a c e ment and e x t r n c t i o n .
.
s.
E a r l y l i t e r a t u r e (Jordan 1891, Juday 1907,
Hallock 1877, Anon. 1878, Land 1913) i n d i c a t e s
t h a t 5. 5. stomias was o r i g i n a l l y abundant but
n o t noted f o r i t s l a r g e s i z e . It reached a
maximum weight of about 2 . 3 kg; o t h e r subspecies
of c u t t h r o a t t r o u t were known t o a t t a i n weights
of 4.5 t o 9 kg a r more.
HABITAT REQUIREMENTS AND LIMITING FACTORS
While no f a c t u a l evidence e x i s t s t o spec i f i c a l l y d e f i n e gre'enback t r o u t h a b i t a t
requirements and l i m i t i n g f a c t o r s , circums t a n t i a l evidence suggests t h a t a l l of those
f a c t o r s r e l a t i n g t o h a b i t a t a l t e r a t i o n and
i n t r o d u c t i o n of non-native t r o u t s which have
caused d e c l i n e s i n o t h e r n a t i v e i n t e r i o r trouts,
have 'had a p a r t i c u l a r l y d e b i l i t a t i n g e f f e c t on
S. 2. stomias. The most obvious f a c t o r prev e n t i n g s u c c e s s f u l r e s t o r a t i o n of t h e greenback t r o u t i n t o i t s o r i g i n a l h a b r t a t i s t h e
presence of non-native t r o u t s . C e r t a i n l y
r e i n t r o d u c t i o n programs f o r greenback t r o u t
cannot achieve success u n l e s s the proposed
s i t e i s completely b a r r e n of a l l non-native
t r o u t s and thoroughly p r o t e c t e d from
re-invasion.
-
PROTECTIVE MEASURES
The U. S. Department of t h e I n t e r i o r
recognizes 2. c. stomias a s a n
endangered s p e c i e s .
I n a c o o p e r a t i v e v e n t u r e undertaken by
the U. S. F o r e s t S e r v i c e , t h e Colorado
~ ~ ~ ~ e r aFishery
t i v e Unit and t h e Colorado
Division of W i l d l i f e i n 1967, c o n s t r u c t i o n of
a f i s h b a r r i e r and e l i m i n a t i o n of t h e brook
t r o u t population above i t c r e a t e d a s a n c t u a r y
for t h e greenback t r o u t i n upper Black Hollow
creek, a t r i b u t a r y t o t h e Poudre River i n
Larimer County, Colorado. A s e l f - r e p r o d u c i n g
of greenback t r o u t was e s t a b l i s h e d
by i n t r o d u c i n g a d u l t greenbacks from Como
creek (Gagnon 1973). But i n 1973, Dale W i l l s ,
U. S F o r e s t S e r v i c e (personal communication
to Robert Behnke) , found two brook t r o u t
above t h e b a r r i e r . A survey conducted i n
August, 1975 by Rolf Nitman, Colorado D i v i s i o n
of W i l d l i f e , found t h e brook t r o u t now t o be
the dominant t r o u t i n t h e creek.
.
R e s t o r a t i o n e f f o r t s on a l a r g e r s c a l e
took p l a c e i n October 1973 when brook t r o u t
were e l i m i n a t e d w i t h antimycin above a n a t u r a l
b a r r i e r i n Hidden Valley Creek, Rocky Mountain
National Park. Complete e r a d i c a t i o n of brook
t r o u t from t h i s c r e e k was made e s p e c i a l l y
d i f f i c u l t due t o t h e presence of about 15 a c r e s
of beaver ponds and a s s o c i a t e d backwaters
(Mullan 1973). A sampling of Hidden Valley
Creek on August 27, 1975 by James Mullan,
U. S. F i s h and W i l d l i f e S e r v i c e , and Dave
Stevens, U. S. National Park S e r v i c e , found
no brook t r o u t , and documented t h e presence of
a d u l t s from t h e 1973 t r a n s p l a n t a s w e l l a s
f i s h from n a t u r a l r e p r o d u c t i o n i n 1974 and
1975. But a n o t h e r t r a n s p l a n t of Como Creek
t r o u t i n t o a b a r r e n headwater s e c t i o n of t h e
North Big Thompson River i n Rocky Mountain
National Park i n 1971 f a i l e d , e v i d e n t l y because a l l t h e f i s h migrated downstream o v e r a
b a r r i e r d u r i n g t h e w i n t e r months. A dense
brook t r o u t population below t h e b a r r i e r makes
i t d o u b t f u l t h a t t h e greenback p o p u l a t i o n w i l l
s u s t a i n i t s e l f t h e r e . I n October 1975 t h e
National Park S e r v i c e t r e a t e d Bear Lake w i t h
antimycin t o e l i m i n a t e t h e brook t r o u t popul a t i o n , and on November 4 introduced greenback
c u t t h r o a t taken from Como Creek.
Other t r a n s p l a n t programs have used
v i r t u a l l y p u r e greenback p o p u l a t i o n s . A 1959
t r a n s p l a n t i n Rocky Mountain N a t i o n a l Park
took greenback t r o u t from t h e headwaters of
the Big Thompson River i n F o r e s t Canyon and
stocked them i n t o Fay Lakes i n t h e park. The
population d i d n o t e s t a b l i s h i t s e l f t h e r e ,
but descendants of t h e o r i g i n a l i n t r o d u c t i o n
have maintained a s e l f - r e p r o d u c i n g population
i n Caddis Lake, immediately below Fay Lakes,
where James Mullan discovered them i n 1972.
S i n c e 1971 t h e C i t y of Boulder has granted
permission t o t h e Colorado D i v i s i o n of W i l d l i f e
t o o b t a i n spawn from a good r e p r e s e n t a t i v e
greenback population i n I s l a n d Lake and up t o
100,000 eggs per y e a r have been taken and
propagated. The Division of W i l d l i f e s t o c k s
t h e s e t r o u t i n t o s e v e r a l mountain l a k e s i n
n o r t h e a s t e r n Colorado a s p a r t of i t s f i s h e r y
management program.
RECOMMENDATIONS
The g r e a t e s t hope f o r expanding t h e
d i s t r i b u t i o n and abundance of 2. 5. stomias i s
by r e i n t r o d u c i n g i t , w i t h i n i t s n a t i v e range,
i n t o s u i t a b l e h a b i t a t b a r r e n of e x o t i c t r o u t s .
Here, i r o n i c a l l y , t h e 1973 Endangered Species
Act a c t u a l l y h i n d e r s management of t h e greenback t r o u t . While t h e i n t e n t of t h e Act is
commendable, i t s p r o h i b i t i o n of t h e "taking"
o r any form of harassment of a n endangered
s p e c i e s would mean c l o s i n g t o a n g l i n g any
stream i n t o which greenback t r o u t a r e i n t r o duced. V i r t u a l l y a l l p o t e n t i a l s i t e s f o r
greenback r e i n t r o d u c t i o n a r e c u r r e n t l y open
t o f i s h i n g . P u b l i c agencies a r e n o t e n t h u s i a s t i c t o i n i t i a t e r e s t o r a t i o n projects f o r an
endangered t r o u t which would r e s u l t i n c l o s i n g
public angling waters.
The s i m p l e s t and most d i r e c t s o l u t i o n t o
t h i s problem would b e f o r t h e U. S. Department
of t h e I n t e r i o r t o change t h e s t a t u s of 2. 5.
s tomias from "endangered" t o "threatened. " A
"threatened" s t a t u s , w h i l e s t i l l a f f o r d i n g
p r o t e c t i o n under t h e Endangered Species Act,
would n o t p r o h i b i t a n g l i n g , thereby allowing
t h i s t r o u t t o be i n c o r p o r a t e d i n t o f i s h e r i e s
management programs and encouraging t h e r e sumption of a c t i v e r e s t o r a t i o n p r o j e c t s . This
r a r e and b e a u t i f u l t r o u t has p o t e n t i a l f o r
inclusion i n special regulation f i s h e r i e s ,
which can s t i m u l a t e p u b l i c support f o r
r e s t o r a t i o n programs, b u t f i r s t i t must be
removed from t h e endangered s p e c i e s l i s t .
Well-organized surveys of i s o l a t e d headw a t e r a r e a s of t h e South P l a t t e and Arkansas
River drainages could f i n d and i d e n t i f y o t h e r
pure o r v i r t u a l l y pure greenback populations,
a s w e l l a s determine p o t e n t i a l s i t e s f o r
reintroductions.
As w i t h 2. 5. p l e u r i t i c u s , i t i s n o t
l i k e l y t h a t many pure populations of 2. 5.
stomias remain, b u t good r e p r e s e n t a t i v e popul a t i o n s , s i m i l a r t o those i n F o r e s t Canyon
and I s l a n d Lake, should be i d e n t i f i e d f o r
s p e c i a l r e c o g n i t i o n i n r e l a t i o n t o perpetuat i o n and p r o t e c t i o n e f f o r t s .
AUTHORITIES
Gagnon, J. G.
1973. The greenback.
Trout 14 (4) :12-28, 30.
Greenback Trout Recovery Team
Greene, W. S.
1937. Colorado t r o u t . Denver Mus. Nat.
H i s t . , Popular S e r . 2, 48 p.
David L a n g l o i s
Colorado D i v i s i o n of W i l d l i f e
Richard Moore
U.S. F o r e s t S e r v i c e
Halloclc, C.
1877. The sportsman's g a z e t e e r and g e n e r a l
guide. New York. 688 p.
Dave Stevens
National Park Service
Johnson, J . E.
1976. S t a t u s of endangered and t h r e a t e n e d
f i s h s p e c i e s i n Colorado. USDI, BLM,
Tech. Note 280. 23 p.
James Mullan
U.S. F i s h and W i l d l i f e S e r v i c e
Robert Behnke
Colorado S t a t e U n i v e r s i t y
(consultant)
Anonymous.
1878. T r o u t i n t h e Rocky Mountains.
and Stream 9(25) :468-469.
Jordan, D. S.
1891. Report on e x p l o r a t i o n s i n Colorado
and Utah d u r i n g t h e summer of 1889, w i t h
am account of t h e f i s h e s found i n each
r i v e r b a s i n examined. B u l l . U. S. F i s h .
Comm. 9:l-40.
Juday, C.
1907. A s t u d y of Twin Lakes, Colorado, with
s p e c i a l c o n s i d e r a t i o n t o t h e foods of t h e
t r o u t s . B u l l . U. S. Bur. F i s h . 26:147-178.
Forest
Behnke, R. J.
1973. The greenback c u t t h r o a t t r o u t , Salmo
c l a r k i s t o m i a s . S t a t u s r e p o r t prepared
f o r U. S. F i s h and W i l d l i f e S e r v i c e ,
Region 11, Albuquerque, N. M. 11 p.
--
Behnke, B. J.
1976. Summary of i n f o r m a t i o n on t h e s t a t u s
of t h e greenback c u t t h r o a t t r o u t , Salmo
c l a r k i stomias. Prepared f o r U.S. F i s h
and W i l d l i f e S e r v i c e , S a l t Lake C i t y Area
O f f i c e . 30- p.
--
Bulkley, R. V.
1959. Report on 1958 f i s h i n g s t u d i e s by t h e
Bureau of S p o r t F i s h e r i e s and W i l d l i f e i n
Rocky Mountain N a t i o n a l Park. Rocky
Mountain S p o r t F i s h e r i e s I n v e s t i g a t i o n s ,
Admin. Rept. 38 p.
Land, S . E.
1913. The b l a c k - s p o t t e d mountain t r o u t
(Salmo stomias and r e l a t e d s p e c i e s ) .
Trans. Am. F i s h . Soc. 42:183-189.
Mullan, J. W.
1973. C o n s i d e r a t i o n s i n p e r p e t u a t i o n of
greenback c u t t h r o a t t r o u t ( S a h o c l a r k i
stomias). Spec. Rept. Fish. Mgmt. Program,
Rocky Mountain Nat. Park. U. S . . F i s h and
W i l d l i f e S e r v i c e , Vernal, Utah. 26 p .
Nelson, W. C.
1972. An u n e x p l o i t e d p o p u l a t i o n of greenback
t r o u t . Colo. Div. of W i l d l i f e , F t . C o l l i n s .
13 p. (mirneo)
Wernsman, G.
1973. S y s t e m a t i c s of n a t i v e Colorado t r o u t .
M. S t h e s i s , Colorado S t a t e Univ., F t .
C o l l i n s . 57 p.
.
LAHONTAN CUTTHROAT
Salmo c l a r k i henshawi
-TYPICAL MERISTIC CHARACTERS
Scale counts
lateral series
(two rows above l a t e r a l
line)
and above l a t e r a l l i n e
( o r i g i n of d o r s a l f i n
to l a t e r a l line)
Vertebrae
150-180
(125-150)~~
33-42
61-63
Gillrakers
40-7 54-
Pylor i c caecae
Basibranchial t e e t h
Numerous and
w e l l developed
SPECIES DESCRIPTION
,
The Lahontan c u t t h r o a t t r o u t achieved i t s
great d i f f e r e n t i a t i o n from a l l other subspecies
of Salmo c l a r k i due t o i t s long physical i s o lation i n the Lahontan basin with t h e r e s u l t ant evolutionary s e l e c t i o n f o r l a c u s t r i n e
s p e c i a l i z a t i o n i n p l u v i a l Lake Lahontan, once
the s i z e of present-day Lake Erie. The number
of g i l l r a k e r s , higher than i n any other western North American t r o u t , f u r t h e r s u b s t a n t i a t e s
the ancient l a c u s t r i n e evolutionary h e r i t a g e
of 2. 2. henshawi; *th few exceptions, o t h e r
taxa of t r o u t possess only 17-21 g i l l r a k e r s .
a Typical values of t r o u t n a t i v e t o t h e
Humboidt River system of Nevada.
The number of pyloric caecae is a l s o higher i n
t h e Lahontan c u t t h r o a t than i n o t h e r subspecies
of 5. c l a r k i .
When Lake Lahontan desiccated 5000 t o
8000 years ago, the separation of i t s major
tributaries effectively isolated the fish
fauna of t h e Carson, Walker, Truckee and
Humboldt r i v e r systems from each other. One
would expect a high degree of genetic v a r i a b i l i t y among the populations of t h e d i f f e r e n t
drainages under such circumstances, but i n
f a c t , a l l specimens examined from pure popul a t i o n s i n t h e Truckee, Carson and Walker
drainages conform t o the diagnosis given
above (Behnke 1960). However, t h e n a t i v e
c u t t h r o a t of t h e Humboldt River system of
Nevada d i f f e r e n t i a t e s recognizably from cutt h r o a t s i n t h e other t r i b u t a r i e s t o ancient
Lake Lahontan. It displays fewer s c a l e s i n
t h e l a t e r a l s e r i e s and a lower number of
g i l l r a k e r s . The Humboldt c u t t h r o a t t r o u t may
represent an undescribed subspecies which
probably separated from g. 2. henshawi much
e a r l i e r than the f i n a l desiccation of Lake
Lahontan, and probably d i f f e r e n t i a t e d i n
response t o evolutionary s t i m u l i t o adapt t o
f l u v i a l conditions i n order t o u t i l i z e t h e
v a s t Humboldt River system (Behnke 1960, 1968,
1972b).
Jordan and Evermanu (1898) described
Salmo c l a r k i tahoensis from Lake Tahoe
-under t h e assumption that: two d i f f e r e n t
c u t t h r o a t t r o u t s , d i f f e r e n t i a t e d by s i z e ,
inhabited Lake Tahoe. However, t h e type
Sacrame
50
100
Kilometers
.......
.:.....
.................
................
,.:.:.:.>
............
.............
....................
..............
.............
.........
............
............
._.,.. So/mo c/arki henshowi
Map 3.
Indigenous distribution of Salmo clarki henshawi and Salmo
clarki seleniris
24
of
2. 2.
tahoensis i s i d e n t i c a l t o
observed s i z e d i f f e r e n c e
t h e presence of both
older f i s h which had r e p e a t e d l y spawned, and
younger f i s h spawning f o r t h e f i r s t t i n e , i n
the spawning runs. Behnke (1960) considexs
S . 5 t a h o e n s i s a synonym of 2. 5. henshabi.
sa1mo evermanni, a name a l s o used t o d e s c r i b e
5 . 5 henshawi, was based on an introduced
~op~latio
ofn Lahontan c u t t h r o a t s i n t h e
.pper Santa Ana R i v e r , C a l i f o r n i a (Benson and
The t r o u t named Salmo r e g a l i s
~ ~ h n k1961).
e
from Lake Tahoe, and 2. smaragdus from Pyramid
Lake, a r e considered t o be based on introduced
t r o u t , 2. g a i r d n e r i (Behnke 1 9 7 2 ~ ) .
c. henshawi and t h e
zrobably r e s u l t e d from
S.
-
Thus, a p r i m o r d i a l c u t t h r o a t invaded t h e
Lahontan b a s i n , probably from t h e Columbia
River b a s i n , and gave r i s e t o a l a r g e l a c u s t ~ i n e
f i s h , 2. 2. henshawi, from which a n
early s e p a r a t i o n l e d t o t h e development of
the c u t t h r o a t t r o u t endemic t o t h e Humboldt
River drainage. Except f o r populat,ions i n habiting Lake Tahoe, Pyramid Lake, Walker
Lake and a few s m a l l e r l a k e s , t h e Lahontan
cutthroat was forced t o become a stream t r o u t
by the d e s i c c a t i o n of Lake Lahontan. This
ultimate d i v i s i o n between l a k e and stream
with its associated evolutionary
programming, d i d n o t r e s u l t i n taxonomic
d i f f e r e n t i a t i o n (except f o r t h a t e x h i b i t e d by
the Humboldt c u t t h r o a t ) , b u t i t i s s i g n i f i c a n t
for subsequent d i s c u s s i o n s concerning l i f e
h i s t o r y , h a b i t a t , and t h e reasons f o r t h e
catastrophic d e c l i n e s i n abundance s u f f e r e d
by t h i s t r o u t .
The s p o t t i n g p a t t e r n of t h e Lahontan
cutthroat c o n s t i t u t e s i t s most d i a g n o s t i c
f i e l d c h a r a c t e r . Large, roundish s p o t s cover
the body evenly and extend onto t h e head and
often t o t h e v e n t r a l s u r f a c e . Other subspecies of i n t e r i o r c u t t h r o a t t r o u t t y p i c a l l y
lack s p o t s on t h e head and v e n t r a l r e g i o n ,
and have s p o t s more concentrated p o s t e r i o r l y
on the caudal peduncle a r e a . C o l o r a t i o n of
the Lahontan c u t t h r o a t i s d u l l when compared
with t h a t of t h e Colorado River c u t t h r o a t o r
the greenback t r o u t . The crimson, gold and
orange c o l o r s , i f p r e s e n t a t a l l , a r e much
subdued.
DISTRIBUTION
The Lahontan c u t t h r o a t t r o u t a t one time
Occurred i n abundance throughout t h e Lahontan
Basin of C a l i f o r n i a and Nevada, w i t h major
lacus t r i n e populations i n Pyramid Lake, Walker
Lake, Independence Lake and Lake Tahoe,
California, and Summit Lake, Nevada; f l u v i a l
Populations occurred i n t h e carsson, Walker and
Truckee River systems of C a l i f o r n i a and i n t h e
Humboldt d r a i n a g e of Nevada.
C u r r e n t l y t h e o n l y l a k e s which harbor
pure s t o c k s of 2. 2. henshawi a r e Summit Lake,
Nevada, and Independence Lake, C a l i f o r n i a . By
1959 t h e only o t h e r known populations conformi n g t o t h e d i a g n o s i s of 2. 2. henshawi occurred
i n Dog Creek of t h e Walker River d r a i n a g e of
C a l i f o r n i a , t h e v e r y headwaters' of t h e E a s t
Carson River above a f a l l s , and one of i t s
t r i b u t a r i e s , Murray Canyon Creek (Behnke 1960).
Behnke discovered a s m a l l , a p p a r e n t l y p u r e
p o p u l a t i o n i n P o l e Creek, t r i b u t a r y t o t h e
Truckee River, i n 1961, but t e n y e a r s l a t e r
extensive electro-fishing disclosed only
brook t r o u t , and t h e n a t i v e c u t t h r o a t of P o l e
Creek i s now presumed e x t i n c t . More r e c e n t l y ,
a p p a r e n t l y p u r e 2. 2. henshawi p o p u l a t i o n s
have been discovered i n Golden Canyon Creek
(an E a s t Carson River t r i b u t a r y ) , By-Day Creek
and E a s t Fork Desert Creek ( i n t h e Walker
River d r a i n a g z ) , and Macklin Creek ( t r i b u t a r y
t o t h e Yuba River i n t h e Sacramento River
b a s i n ) . The Macklin Creek p o p u l a t i o n i s
probably t h e r e s u l t of a n e a r l y t r a n s p l a n t
from t h e Truckee River. A t r a n s p l a n t from
Macklin Creek . i n t o a b a r r e n , i s o l a t e d s e c t i o n
of E a s t Fork Creek of t h e Yuba River d r a i n a g e
i n 1970 and 1971 h a s e s t a b l i s h e d a smll
p o p u l a t i o n t h e r e ( C a l i f o r n i a Department of
F i s h and Game, Threatened Trout Committee
n o t e s ; Stephen Nicola, p e r s o n a l communication
t o R. Behnke).
Both C a l i f o r n i a and Nevada a n n u a l l y
propagate m i l l i o n s of "2. 2. henshawi", b u t
t h e g r e a t m a j o r i t y o f t h e s e h a t c h e r y f i s h come
from t h e Heenan Lake s t o c k which o r i g i n a t e d
from a t r a n s p l a n t of 2. 2. henshawi from t h e
Carson River--a f l u v i a l , n o t a l a c u s t r i n e
population--into Blue Lake, C a l i f o r n i a , i n
1864. Two subsequent i n t r o d u c t i o n s of rainbow
t r o u t i n t o Blue Lake r e s u l t e d i n h y b r i d i z a t i o n
b e f o r e t h e e s t a b l i s h m e n t of t h e p r e s e n t s t o c k
i n Heenan Lake. The Heenan Lake " c u t t h r o a t "
bears a good phenotypic resemblance t o 2. 2.
henshawi, b u t t h e lower number of s c a l e s and
g i l l r a k e r s (Behnke 1960) and t h e makeup of i t s
blood serum ( U t t e r and Ridgway 1966) d i s c l o s e
t h e rainbow t r o u t i n f l u e n c e . Thus, t h e t r o u t
widely propagated a s 2. 5. henshawi i s i n
r e a l i t y a c o u n t e r f e i t of t h e r e a l t h i n g , and
t h e widespread i n t r o d u c t i o n of t h e Heenan
Lake s t o c k i n C a l i f o r n i a and Nevada i s n o t
considered a s p a r t of t h e d i s t r i b u t i o n of t h e
t r u e &. 2. henshawi.
STATUS AND POPULATION TREND
Commercial f i s h e r i e s h a r v e s t e d v a s t numb e r s o f Lahontan c u t t h r o a t t r o u t , famed f o r
i t s abundance and s i z e , from Pyramid Lake,
Walker Lake and Lake Tahoe during t h e l a s t
h a l f of t h e n i n e t e e n t h c e n t u r y , supplying t h e
needs of towns and mining camps i n t h e a r e a
and s h i p p i n g s u r p l u s f i s h by Wells Fargo
express t o S a n Francisco and o t h e r c i t i e s .
Robert Behnke, i n a 1974 r e p o r t prepared f o r
t h e P a i u t e t r i b e ' s l i t i g a t i o n over the water
r i g h t s and f i s h e r y values of Pyramid Lake,
conservatively estimated t h a t t h e c u t t h r o a t
t r o u t of Pyramid Lake alone could have supported a f i s h e r y of 454,000 kg p e r year i n
the n i n e t e e n t h century. And y e t t h e famed
Pyramid Lake c u t t h r o a t s t o c k was allowed t o
become e x t i n c t i n 1938 (Sumner 1940) d e s p i t e
t h e f a c t t h a t i t was t h e l a r g e s t of a l l
western t r o u t s ; t h e average s i z e of f i s h
caught i n 1938 was n i n e kg (Sumner 1940), and
even though t h e o f f i c i a l record f o r t h i s
t r o u t (and t h e world record c u t t h r o a t t r o u t )
was 18.6 kg, t h e I n d i a n f i s h e r y a t Pyramid
Lake r e p o r t e d t r o u t weighing up t o 28 kg
(Wheeler 1969).
Fish commission r e p o r t s of Nevada and
C a l i f o r n i a and o t h e r e a r l y l i t e r a t u r e condemned rampant poaching, uncontrolled exploi. t a t i o n and damming, d i v e r s i o n and p o l l u t i o n
of t h e r i v e r s . But o v e r f i s h i n g d i d n o t b r i n g
about t h e v i r t u a l demise of g. 5. henshawi.
Blockage of spawning t r i b u t a r i e s decimated
the l a c u s t r i n e populations, and the i n t r o duction of non-native t r o u t s i n t o t h e streams
of t h e Lahontan b a s i n caused replacement o r
h y b r i d i z a t i o n of t h e n a t i v e c u t t h r o a t t r o u t
i n the rivers.
It may seem s t r a n g e t h a t such a l a r g e
t r o u t , once s o abundantly d i s t r i b u t e d througho u t t h e g r e a t a r e a of t h e Lahontan b a s i n
could so r a p i d l y s l i d e toward e x t i n c t i o n .
The populations i n h a b i t i n g Pyramid, Tahoe
and Walker Lakes were s p e c i a l i z e d t o e x i s t i n
a l a c u s t r i n e h a b i t a t ; they had adapted v e r y
highly t o t h e i r environment. These stocks
appeared g r e a t l y r e s i s t a n t t o t h e e f f e c t s of
h y b r i d i z a t i o n , perhaps through n e g a t i v e
s e l e c t i o n toward any' hybrids produced. The
o r i g i n a l c u t t h r o a t t r o u t of Pyramid Lake and
Lake Tahoe maintained t h e i r stocks u n t i l t h e
19301s, d e s p i t e massive stocking of rainbow
t r o u t i n t o t h e lakes and t r i b u t a r i e s s i n c e
before 1890, and d e l i b e r a t e experimental
h y b r i d i z a t i o n i n hatchery propagation (Behnke
1960). But i n 1906, t h e Newlands I r r i g a t i o n
p r o j e c t constructed Derby Dam on t h e Truckee
River, 30 m i l e s above Pyramid Lake. Thus,
the Pyramid Lake c u t t h r o a t t r o u t were denied
access t o most of t h e spawning h a b i t a t of
the Truckee River (Snyder 1917). Even s o ,
t h e s e t r o u t were t o maintain t h e i r numbers
u n t i l t h e 19201s, when d i v e r s i o n of t h e
e n t i r e flow of t h e Truckee became more f r e quent, with consequent g r e a t l o s s e s of
spawning t r o u t . The l a s t spawning r u n of
t r o u t i n t h e Truckee River occurred i n 1938
(Sumner 1940), but streamflow was i n s u f f i c i e n t
f o r reproductive success and t h i s magnificent
r a c e became e x t i n c t . I n Lake Tahoe, damming,
p o l l u t i o n and s i l t a t i o n of i t s t r i b u t a r i e s
r e s u l t e d i n t h e demise of t h e n a t i v e c u t t h r o a t
soon t h e r e a f t e r . The c u t t h r o a t t r o u t of
Walker Lake held on u n t i l 1948 when 16 l a r g e
spawners were trapped near t h e mouth of t h e
Walker River, which, due t o i r r i g a t i o n d i v e r s i o n s , no longer had flows s u f f i c i e n t f o r the
reproductive requirements of the t r o u t i n the
l a k e . The Nevada Department of Fish and Game
removed spawn from these t r o u t and began a
brood s t o c k ; t h e p r e s e n t population of Walker
Lake i s maintained by h a t c h e r y propagation
(Behnke 1960, Johnson 1974).
S . 2. henshawi possessed a n evolutionary
h e r i t a g e which made i t h i g h l y adapted and
s u c c e s s f u l i n l a k e environments; i t was much
l e s s z u i t e d f o r stream e x i s t e n c e and q u i t e
vulnerable, i n f l u v i a l environments, t o d i s placement by brook, brown and rainbow t r o u t s
and t o h y b r i d i z a t i o n with rainbow and nonn a t i v e c u t t h r o a t t r o u t s . Today only a v e r y
few streams s h e l t e r pure stocks of Lahontan
cutthroat t r o u t (see page 22).
The p u r i t y of t h e Walker Lake s t o c k ,
propagated i n Nevada, i s i n doubt. No
a n c i e n t museum specimens e x i s t f o r study of
t h e o r i g i n a l population, and ample opportunity
f o r h y b r i d i z a t i o n i n t h e Walker River has
e x i s t e d f o r more than h a l f a century. Indeed,
specimens of t h e s t o c k r a i s e d a t Verdi, Nevada,
have s l i g h t l y lower g i l l r a k e r counts and scale
counts than i s t y p i c a l of pure 2.
henshawi
(Behnke 1960). But t h e highly a l k a l i = a k e r
Lake environment, l e t h a l t o a l l o t h e r t r o u t s ,
probably e x e r t e d s e l e c t i v e p r e s s u r e s s t r o n g
enough t o maintain t h e genotype of t h e Walker
Lake c u t t h r o a t without s i g n i f i c a n t modification
from hybridization. The c u t t h r o a t t r o u t of
Walker Lake may p l a y an i n c r e a s i n g l y s i g n i f i c a n t r o l e i n propagation e f f o r t s involving a
l a r g e , l a c u s t r i n e predator. Cutthroat t r o u t s
of Walker and Independence Lakes a r e t h e only
e x i s t i n g s t o c k s t h a t have h i s t o r i c a l l y coexisted
with o t h e r d e m e n t s of t h e n a t i v e f i s h fauna of
t h e Lahontan b a s i n and a s such might be
expected t o possess t h e g e n e t i c programming
f o r maximizing e f f e c t i v e coexistence w i t h and
u t i l i z a t i o n of t h i s a s s o c i a t e d fauna i n other
lakes.
The n a t i v e c u t t h r o a t t r o u t of t h e ~umboldt
River drainage of t h e Lahontan Basin of Nevada
has f a r e d b e t t e r than 5, 2. henshawi i n t h e
r e s t of t h e basin. This t r o u t , e v i d e n t l y more
s p e c i a l i z e d f o r stream l i f e and apparently
h i g h l y adapted t o t h e harsh flood-dr,ought
c y c l e of t h i s a r i d region, has p e r s i s t e d i n
many small streams d e s p i t e repeated introduct i o n s of non-native t r o u t s . Pure o r essentially
pure populations e x i s t i n about 20 streams
Behnke, personal n o t e s and d a t a ) . The
t r o u t populations i n some s m a l l streams
r e s t r i c t e d t o a few s m a l l pools and
ponds i n l a t e summer, when t h e streams
i n t e r m i t t e n t . Although t h e undescribed
of t h e Humboldt d r a i n a g e p e r s i s t s
in s e v e r a l l o c a l i t i e s , i t cannot be considered
as common o r abundant, and m e r i t s t h e same
f o r p r o t e c t i o n and r e s t o r a t i o n
5. c. henshawi.
(R. J.
,,tire
be
beaver
become
,,
Bond (1961, 1966) l i s t e d 5. 5. henshawi
as the n a t i v e t r o u t of t h e Alvord d e s i c c a t i n g
basin, which i s contiguous w i t h t h e n o r t h e r n
Lahontan b a s i n on t h e Oregon-Nevada border.
Behnke (1960) recognized t h a t t h e r e were two
d i s t i n c t groups of c u t t h r o a t t r o u t i n t h i s
basin (or b a s i n s ) , one i n t h e V i r g i n Creek
Trout Creek d r a i n a g e of t h e Alvord Lake sump
and one i n Willow and Whitehorse Creeks, which
drain o u t onto t h e d e s e r t e a s t of Alvord Lake
a t a h i g h e r e l e v a t i o n . A t t h a t time Behnke
believed t h a t t h e t r o u t c o l l e c t e d from V i r g i n
Creek, which possessed 21-25 g i l l r a k e r s , were
probably introduced Lahontan c u t t h r o a t t r o u t
and t h a t t h e Willow and Whitehorse Creek populations c o n s t i t u t e d a n undescribed subspecies.
Subsequent information and re-examination of
the Virgin Creek specimens h a s caused Behnke
to r e j e c t h i s previous b e l i e f t h a t t h e s e
specimens a r e 5. g. henshawi. Though t h e
Lahontan c u t t h r o a t may have gained a c c e s s t o
Virgin Creek and t h e Alvord b a s i n v i a a n
ancient connection w i t h Summit Lake, t h e
specimens a r e s u f f i c i e n t l y d i s s i m i l a r t o be
c l a s s i f i e d a s a new subspecies (Behnke 1972b,
1973). The n a t i v e t r o u t of t h e V i r g i n Creek
Trout Creek d r a i n a g e of t h e Alvord b a s i n o f
Nevada and Oregon a r e presumed e x t i n c t , s i n c e
no specimens have been c o l l e c t e d s i n c e 1934.
The c h a r a c t e r i s t i c s of t h e c u t t h r o a t t r o u t i n
Willow and Whitehorse Creeks a r e c l o s e t o t h e
Humboldt c u t t h r o a t of t h e Lahontan b a s i n and
their o r i g i n may have r e s u l t e d from a headwater
stream c a p t u r e from t h e Humboldt system. Native t r o u t s t i l l e x i s t i n Willow and Whitehorse
Creeks but remain u n c l a s s i f i e d .
-
-
Due t o t h e extreme r a r e n e s s of pure
t h e U. S. Department of
-S.I n tc.e r i henshawi,
o r endowed i t w i t h t h e s t a t u s of
the
"endangered." But t o f a c i l i t a t e management
and r e s t o r a t i o n e f f o r t s , t h e s t a t u s of t h e
Lahontan c u t t h r o a t t r o u t was changed from
''endangered" t o "threatened" (Federal R e g i s t e r
40(137), 16 J u l y 1975). This a c t i o n a l s o
avoided t h e problem of a t t e m p t i n g t o e n f o r c e
the "no taking" p r o v i s i o n of t h e Endangered
Species Act of 1973 i n t h e popular s p o r t
fishery a t Pyramid Lake, where pure 2. 2.
henshawi from Summit Lake, p a r t i a l l y h y b r i d i z e d
5. 5. henshawi from t h e Heenan Lake s t o c k and
F1rainbow x c u t t h r o a t h y b r i d s have a l l been
Stocked t o g e t h e r t o provide a n g l i n g .
LIFE HISTORY
Snyder (1917) made many g e n e r a l observat i o n s r e l a t i n g t o l i f e h i s t o r y of Lahontan
c u t t h r o a t t r o u t , mainly t h e Pyramid Lake stock.
Juday (1907) published some d a t a on Lake Tahoe
c u t t h r o a t . Calhoun (1944a, 1944b) d e s c r i b e d
some l i f e h i s t o r y a t t r i b u t e s of t h e p a r t i a l l y
h y b r i d i z e d Heenan Lake t r o u t i n Blue Lake and
Heenan Lake. Lea's (1968) M. A. t h e s i s on t h e
Independence Lake c u t t h r o a t c o n t a i n s t h e most
comprehensive d a t a on a pure population of
S. 2. henshawi.
-
A11 of t h e above s t u d i e s were based on
l a c u s t r i n e s t o c k s . The work of Calhoun (1944a),
which p o i n t s o u t t h e v a r i a b i l i t y i n growth,
age a t m a t u r i t y , food h a b i t s and o t h e r l i f e
h i s t o r y f a c t o r s between populations of t h e
same s t o c k ( t h e Heenan Lake s t r a i n ) l i v i n g i n
Blue Lake and i n Heenan Lake demonstrates t h a t
t h e s p e c i f i c d e t a i l s gained from any l i f e
h i s t o r y s t u d y must b e r e s t r i c t e d i n a p p l i c a t i o n
t o t h e s i t e of t h e s t u d i e s . Broad g e n e r a l i z a t i o n s a p p l i e d t o o t h e r populations might prove
erroneous.
Based on a l l t h e s e s t u d i e s , p a r t i c u l a r l y
t h a t of Lea (1968), i t may be assumed t h a t i n
l a k e s , g. g. henshawi tends t o feed more i n
t h e p e l a g i c zones and on t h e s u r f a c e . When
a v a i l a b l e , f i s h become predominant i n i t s
d i e t when i t reaches a s i z e of about 30.5 cm.
I n Independence Lake, t h e r e d s i d e s h i n e r ,
kokanee salmon and P a i u t e s c u l p i n were t h e
main f i s h e a t e n .
The g e o l o g i c h i s t o r y of t h e Lahontan
b a s i n and t h e d i s t i n c t i v e c h a r a c t e r s of 2. 5.
henshawi i n d i c a t e t h a t t h i s t r o u t has had t h e
l o n g e s t period of e v o l u t i o n of any w e s t e r n
t r o u t i n which t o s p e c i a l i z e a s a l a r g e
p r e d a t o r i n a l a c u s t r i n e environment (Behnke
1972~).
The weak l i n k i n t h e l i f e c y c l e of 5. 2.
henshawi concerns i t s r e p r o d u c t i v e requirements;
i t i s a n o b l i g a t o r y stream spawner. The subs p e c i e s ' superb a d a p t a b i l i t y t 6 t h e Truckee
Pyramid Lake system was negated by t h e
River
blockage of a c c e s s t o spawning h a b i t a t i n t h e
Truckee River.
-
-
S. g. henshawi w e l l i l l u s t r a t e s c e r t a i n
ideas regarding i n t r a s p e c i f i c v a r i a b i l i t y i n
e c o l o g i c a l , p h y s i o l o g i c a l , and b e h a v i o r a l
t r a i t s . The v a r i o u s s t o c k s , i s o l a t e d thousands
of y e a r s ago by t h e d e s i c c a t i o n of Lake
Lahontan, were s u b j e c t e d t o t h e i r own unique
g e n e t i c programming under n a t u r a l s e l e c t i o n i n
d i f f e r e n t environments. and t h i s was o a r t i c u l a r l y t r u e i n l a c u s t r i n e v e r s u s f l u v i a l populat i o n s . Probably only t h e Pyramid Lake
population of 2. 2. henshawi continuously
evolved i n a l a r g e l a k e environment w i t h a
f u l l range of the Lahontan b a s i n fauna.
I n t e r p r e t a t i o n of t h i s evidence suggests
t h a t no e x i s t i n g t r o u t c l a s s i f i e d a s 2. 2.
henshawi, introduced i n t o Pyramid Lake, can be
expected t o d u p l i c a t e t h e adaptive success and
l a r g e s i z e of t h e o r i g i n a l Pyramid Lake S. g.
henshawi, due t o s u b t l e d i f f e r e n c e s i n t h e i r
l i f e h i s t o r y c h a r a c t e r i s t i c s . This i n t e r p r e t a t i o n i s supported by t h e f a c t t h a t i n almost
two decades of stocking "2. g. henshawi" i n t o
Pyramid Lake, t h e maximum s i z e recorded has
n o t reached t h e average s i z e of t h e o r i g i n a l
s t o c k recorded d u r i n g i t s 1938 spawning run,
and only reaches one-third t o one-half t h e
maximum s i z e once a t t a i n e d by t h e now-extinct
Pyramid Lake c u t t h r o a t (Behnke 1968, 1972a,
1972c; Trojnar and Behnke 1974).
HABITAT REQUIREMENTS AND LIMITING FACTORS
The l a c k of s u i t a b l e stream spawning
h a b i t a t has l i m i t e d l a c u s t r i n e populations of
S. g. henshawi. Although hatchery propagation
and stocking i n t o lakes provide a means of
avoiding t h i s l i m i t i n g f a c t o r , u n t i l brood
s t o c k s of 5. 2. henshawi a r e g r e a t l y expanded,
t h e i n t r o d u c t i o n of 2. g. henshawi x 2.
g a i r d n e r i hybrids cannot be considered an
a u t h e n t i c r e s t o r a t i o n of t h e Lahontan c u t throat.
-
Stream populations of Lahontan c u t t h r o a t
have s u f f e r e d from h y b r i d i z a t i o n with rainbow
t r o u t , except i n t h e Humboldt River basin.
Many of t h e streams i n which t h e Humboldt
c u t t h r o a t occurs have a long h i s t o r y of stocki n g w i t h rainbow t r o u t , Yellowstone c u t t h r o a t ,
and brook and brown t r o u t . The only reasonable
explanation f o r t h e r e s i s t a n c e of t h e Humboldt
c u t t h r o a t t o displacement and h y b r i d i z a t i o n
might be t h i s t r o u t ' s s u p e r i o r a d a p t a t i o n t o
i t s harsh environment.
A unique t o l e r a n c e t o high a l k a l i n i t y
l e v e l s , which can be a t t r i b u t e d t o a physiol o g i c a l a d a p t a t i o n t o t h e environments of
Lake Lahontan during i t s period of d e s i c c a t i o n
and i n c r e a s i n g concentrations of dissolved
s o l i d s , allows 5. 2. henshawi (or t r o u t with
a predominant 2. g. henshawi genotype) t o
t h r i v e i n waters such a s Walker Lake which
a r e l e t h a l t o a l l o t h e r t r o u t s (Johnson 1974).
The mechanisms of " a l k a l i n i t y t o x i c i t y " and
p r e c i s e l y which i o n s a r e t o x i c t o o t h e r t r o u t s ,
y e t t o l e r a t e d by S, 2. henshawi, remain unknown. But t h i s unique adaptation t o an
environmental extreme by S. 5. henshawi could
prove u s e f u l i n e s t a b l i s h i n g f i s h e r i e s i n
lakes where o t h e r t r o u t s could n o t survive.
PROTECTIVE MEASURES
The Threatened Trout Committee of t h e
C a l i f o r n i a Department of Fish and Game has
conducted surveys t o f i n d remnant populations
of 2. c, henshawi and t o determine s i t e s f o r
establishment of new populations by t r a n s p l a n t s ,
A s u c c e s s f u l t r a n s p l a n t of t h i s subspecies
from Macklin Creek t o t h e barren headwaters of
nearby E a s t Fork Creek took place i n 1970 and
1971. Propagation of Independence Lake c u t t h r o a t began p r i m a r i l y t o maintain t h e s t o c k
i n Independence Lake; 32,000 t r o u t from eggs
taken i n 1974 were on hand i n 1975. Of these,
5000 were marked and stocked i n Heenan Lake
t o f a c i l i t a t e f u t u r e propagation and 25,000
were restocked i n t o Independence Lake (Threatened Trout Committee, C a l i f o r n i a Department
of Fish and Game minutes of meetings; Stephen
Nicola, personal communication t o Robert
Behnke). Removal of t h e beaver dams which
blocked t h e spawning run from Independence
Lake i n 1964 g r e a t l y increased t h e success of
n a t u r a l reproduction of t h i s s t o c k (Lea 1968).
The impact and p o t e n t i a l t h r e a t t o t h e
Independence Lake c u t t h r o a t s t o c k by t h e
planned Walt Disney Productions r e s o r t t o be
b u i l t a t Independence Lake, i s d i f f i c u l t t o
f o r e c a s t . The obvious t h r e a t of eutrophication
e x i s t s , b u t more important might be a demand
f o r stocking g r e a t numbers of t r o u t t o meet'
increased f i s h i n g p r e s s u r e i n Independence Lake.
Hopefully, developers w i l l recognize t h e
uniqueness and value of t h e n a t i v e Lahontan
c u t t h r o a t of Independence Lake and design a
propagation program and s p e c i a l r e g u l a t i o n
f i s h e r y based on t h i s f i s h and perhaps kokanee
salmon.
The U. S. Fish and W i l d l i f e S e r v i c e
propagates t h e pure s t r a i n of 2. 2. henshawi
i n Summit Lake w i t h t h e o b j e c t i v e of r e s t o r i n g
i t i n Pyramid Lake. The u l t i m a t e g o a l i s t o ree s t a b l i s h n a t u r a l reproduction i n t h e Truckee
River, once adequate flows and f i s h passage
f a c i l i t i e s become a r e a l i t y i n the lower
Truckee River (Gary Rankel, U. S. Fish and
W i l d l i f e Service, personal communication t o
Robert Behnke). But a s noble a s t h i s goal
may be, p r e s e n t conditions i n t h e Truckee,
particularly the potential f o r hybridization
w i t h t h e abundant rainbow t r o u t population
which e x i s t s t h e r e , i n d i c a t e s t h a t i t s r e a l i z a t i o n w i l l be d i f f i c u l t i f n o t impossible.
I n r e c o g n i t i o n of t h e s i g n i f i c a n c e of the
Mahogany Creek watershed, t h e only spawning
t r i b u t a r y a v a i l a b l e t o t h e Summit Lake cutthroat
stock, t h e Bureau of Land Management removed
t h e watershed from mining exploration t o prot e c t t h i s stream from f u r t h e r degradation.
But i t f a i l e d t o i n s t i t u t e t h e grazing controls
which had been proposed, and consequent e f f e c t s
of overgrazing r e s u l t e d i n t h e need t o remove
s i l t buildup a t t h e mouth of the s t r e i m each
year t o allow t h e spawning t r o u t t o e n t e r t h e
stream. The BLM c i t e d t h e e f f e c t s of l i v e stock g r a z i n g on the Summit Lake c u t t h r o a t i n
its environmental impact s t a t e m e n t on g r a z i n g
in
Nevada (Anonymous 1974) a s a n example of
the problems of multiple-use management on
public lands when l i v e s t o c k i n t e r e s t s wield
the predominant i n f l u e n c e - - d e s p i t e n a t i o n a l
r e g a r d i n g t h e s u r v i v a l of an
species.
I n t h e Humboldt d r a i n a g e , a s u c c e s s f u l
transplant of t h e n a t i v e t r o u t from F r a z e r
creek t o Sherman Creek, Elko County, Nevada
has taken p l a c e , w i t h f u t u r e t r a n s p l a n t s
a n t i c i p a t e d . The new Sherman Creek population
has been observed i n water temperatures r e a h ing 25.6' C . , perhaps a r e c o r d high temperature f o r c u t t h r o a t t r o u t i n n a t u r a l c o n d i t i o n s
(pat Coffin, Nevada F i s h and Game Department,
personal communication t o Robert Behnke).
The importance o f the Lahontan c u t t h r o a t
trout both i n propagation a s a s p o r t f i s h and
for t h e r o l e i t plays i n f i s h e r i e s management
d i c t a t e s two goals f o r t h e management and
r e s t o r a t i o n of t h i s t r o u t :
1. I d e n t i f i c a t i o n , p r o t e c t i o n and
t r a n s p l l n t g of pure p o p u l a t i o n
2. Propagation of pure S. 2. henshawi
to r e p l a c e t h e h y b r i d i z e d Heenan Lake s t r a i n
for s r o c k i n g i n t h e Lahontan basin.
Some compromises might be encouraged i n
s e l e c t i o n of s t o c k s i n o r d e r t o c r e a t e t h e
best-adapted genotype f o r waters such a s
Pyraaiid Lake. The Summit Lake p o p u l a t i o n ,
the major pure s t o c k of 2. 2. henshawi a v a i l able f o r propagation, has probably been
i s o l a e d from a l l o t h e r f i s h e s f o r s e v e r a l
thousand y e a r s . Crossings of t h e Summit Lake
t r o u t w i t h Independence Lake c u t t h r o a t and/or
Walker Lake c u t t h r o a t might r e s u l t i n a
broader base o f h e r t e r o z y g o s i t y and g r e a t e r
a d a p t a b i l i t y t o new w a t e r s . Because v i r t u a l l y
a l l i n t r o d u c t i o n s of hatchery-propagated
S o c . - h e n s h a w i occur i n l a k e s where n a t u r a l
reproduction does n o t occur, no n e g a t i v e
impact would b e expected from experimental
\
interracial hybridization i n a restoration
progrkm f o r pure S. 5 henshawi. Of c o u r s e ,
the o n l y t r o u t stocked i n t o Independence Lake,
where n a t u r a l r e p r o d u c t i o n does occur, should
be from t h e n a t i v e population.
-
One promising o p t i o n of a propagation
program should b e t e s t e d and t h a t concerns t h e
propagation from p a r e n t s s u r v i v i n g i n t h e new
environment t o t a k e advantage of n a t u r a l s e l e c t i o n f a v o r i n g c e r t a i n h e r i d i t a r y t r a i t s . For
example, t h e s t o c k i n g of Summit Lake c u t t h r o a t
t r o u t i n t o Pyramid Lake is p r e s e n t l y accomp l i s h e d by a n annual egg t a k e a t Summit Lake
s o t h a t each g e n e r a t i o n i n Pyramid Lake is
d e r i v e d d i r e c t l y from Summit Lake. A comparison should b e made o v e r s e v e r a l g e n e r a t i o n s
i n r e l a t i o n t o s u r v i v a l and c o n t r i b u t i o n t o
t h e Pyramid Lake f i s h e r y , between f i s h propagated from eggs t a k e n a t Summit Lake and
from eggs t a k e n from Summit Lake t r o u t
s u r v i v i n g t o m a t u r i t y i n Pyramid Lake. An
i t e m i n t h e Sport F i s h i n g I n s t i t u t e B u l l e t i n
( A p r i l , 1976) i s of p a r t i c u l a r r e l e v a n c e i n
t h i s r e s p e c t . A r a c e of Columbia River coho
salmon stocked i n t h e Lamprey R i v e r , New
Hampshire, gave a t o t a l s u r v i v a l o f a d u l t s
r e t u r n i n g t o t h e home s t r e a m o f 1.22 p e r c e n t ,
b u t t h e F1 g e n e r a t i o n r e s u l t i n g from eggs
taken from t h e r e t u r n i n g salmon y i e l d e d a
t o t a l s u r v i v a l of 5.75 p e r c e n t o r a 4.7 f o l d
i n c r e a s e i n s u r v i v a l and a l s o a 50 p e r c e n t
i n c r e a s e i n average weight of s u r v i v i n g
salmon.
The Walker Lake s t r a i n needs a n evaluat i o n of i t s r e l a t i v e p u r i t y . The Humboldt
n a t i v e c u t t h r o a t needs a n e s t a b l i s h e d l a k e ,
s i m i l a r t o Heenan Lake, f o r i t s propagation.
This t r o u t possesses a good f i s h e r i e s management p o t e n t i a l , acquired d u r i n g i t s r e c e n t
e v o l u t i o n under t h e h a r s h c l i m a t i c regime of
n o r t h e a s t e r n Nevada. When i t has gained
access t o r e s e r v o i r s from i t s headwater s t r o n g holds d u r i n g h i g h runoff y e a r s , t h e Humboldt
c u t t h r o a t h a s g r e a t l y exceeded h a t c h e r y t r o u t
i n both growth and s u r v i v a l (Behnke 1968 and
personal data).
A propagation program f o r 2. 5. henshawi
and t h e Humboldt c u t t h r o a t should have a s one
of i t s g o a l s t h a t of demonstrating t h e pract i c a l v a l u e s of p r e s e r v i n g and u t i l i z i n g t h e
g e n e t i c d i v e r s i t y of r a r e and endangered
t r o u t s t o a g a i n make t h e s e f i s h a dominant
element i n t h e i r n a t i v e range.
AUTHORITIES
1. Robert Behnke
Dept. of Fishery and W i l d l i f e Biology
Colorado S t a t e University
F o r t C o l l i n s , CO 80521
(taxonomy of 2. 2. henshawi, Humboldt
c u t t h r o a t and t r o u t of contiguous basins)
2.
V i r g i l K. Johnson
Nevada Department of Fish and Game
Box 10678
Reno, NV 89510
1972c. The systematics of salmonid f i s h e s
of r e c e n t l y g l a c i a t e d lakes. Jour. Fish.
Res. Bd. Canada 29(6):639-671.
Benson, S. B. and R. J. Behnke.
1961. Salmo evermanni a synonym of Salmo
c l a r k i henshawi. C a l i f . Fish and Game
47(3):257-259.
Bond, C. E.
1961. Keys t o Oregon freshwater f i s h e s .
Agric. Exp. S t a . , Oregon S t a t e Univ.,
Corvallis. Tech. Bull. 58. 42 p.
(management of Pyramid Lake f i s h e r i e s )
3.
Don King and Gary Rankel
U.S. F i s h and W i l d l i f e Service
300 Booth St., Rm. 4005
Reno, NV 89502
(Federal p r o j e c t s on r e s t o r a t i o n and
management of 2. 5. henshawi)
4.
Stephen Nicola
C a l i f o r n i a Department of F i s h and Game
(5. 5.
henshawi p r o j e c t s i n California)
REFERENCES
1966. Endangered p l a n t s and animals of
Oregon, Vol. I. Fishes. Agric. Exp. Sta.,
.Oregon S t a t e Univ., Corvallis. Spec. Report 205. 8 p.
Galhoun, A . J.
1944a. The food of t h e black-spotted trout
i n tno S i e r r a Nevada lakes. C a l i f . Fish
and Game 30(2):80-85.
1944b. Black-spotted t r o u t i n Blue Lake,
Cal'if ornia. C a l i f . Fish and Game 30 (1) :
22 -42.
Anonymous.
1974. E f f e c t s of l i v e s t o c k grazing on wildl i f e , watershed, r e c r e a t i o n and o t h e r r e source values i n Nevada. Bureau of Land
Management, Nevada S t a t e Office, Reno.
C a l i f o r n i a Department of Fish and Game.
1965. Species plans: Lahontan c u t t h r o a t
t r o u t . I n C a l i f o r n i a Fish and Wildlife
.
of Fish and Game,
Plan, ~ a c f Dept.
Sacramento. Vol. 11:119, 147.
Behnke, R. J.
1960. Taxonomy of t h e c u t t h r o a t t r o u t of
t h e Great Basin with notes on the rainbow
s e r i e s . M. A. Thesis, Univ. of California,
Berkeley. 98 p:
Johnson, K.
1974. Angler's guide t o Walker Lake.
Nevada Outdoors and Wildlife Review 8(1):
15-18.
1968. Rare and endangered species: the
n a t i v e t r o u t s of western North America.
Proc. West. Assoc. S t a t e Game and Fish
Comm. 48:533-535.
.
.
Jordan, D. S and B W. Evermann.
1898. The f i s h e s of North and Middle America.
Bull. U. S. Nat. Mus. 47 (pt. 3):2184-3136.
Juday, C.
1907. Notes on Lake Tahoe, i t s t r o u t and
t r o u t f i s h i n g . Bull. U. S. Bur. Fish.
26:133-146.
1972a. The r a t i o n a l e of preserving genetic
d i v e r s i t y : examples of the u t i l i z a t i o n of
i n t r a s p e c i f i c races of salmonid f i s h e s i n
f i s h e r i e s management. Proc. West. Assoc.
S t a t e Gam'e and Fish Comm. 52:559-561.
LaRivers, I.
1962. Fishes and f i s h e r i e s of Nevada.
Fish and Game Comm., Reno. 782 p.
1972b. Rare and endangered t r o u t s of t h e
Southwest. I n Symp. on Rare and Endanz the Southwestern United
gered ~ i l d l i of
S t a t e s . New Mexico Department of Game
and Fish, Santa Fe. p. 129-133.
Lea, R. N.
1968. Ecology of the Lahontan c u t t h r o a t
t r o u t , Salmo c l a r k i henshawi, i n Independence Lake, California. M. A. Thesis,
Univ. of C a l i f o r n i a , Berkeley. 95 p.
Nev.
~ ~ A f e W.
e , R.
1966. Lahontan c u t t h r o a t t r o u t . 3 A . J.
calhoun
(ed. .) ., I n l a n d F i s h e r i e s ~ d a g e m e n t
c a l i f . Dept. of F i s h and Game, Sacramento.
p. 225-231.
-
-
Rankel G. L.
1976. F i s h e r y management program, Summit
Lake I n d i a n R e s e r v a t i o n , Humboldt County,
Nevada. U.S. F i s h and W i l d l i f e Serv.,
Div. F i s h S e r v i c e s , Reno, Nevada, S p e c i a l
Rep. 35 P.
snyder, J. 0.
1917. F i s h e s of t h e Lahontan system of
Nevada and n o r t h e a s t e r n C a l i f o r n i a . B u l l .
U. S. Bur. F i s h . 35:31-86.
Sumner, F. H.
1940. The d e c l i n e o f t h e Pyramid Lake
f i s h e r y . Trans. h e r . F i s h . Soc. 69:216224.
.
T r o j n a r , J. R. and R. J. Behnke.
1974. Management i m p l i c a b i o n s o f e c o l o g i c a l
s e g r e g a t i o n between two i n t r o d u c e d popul a t i o n s of c u t t h r o a t t r o u t i n a s m a l l
Colorado l a k e . Trans. Am. F i s h . Soc.
103 (3) :423 -430.
U t t e r , F. M. and G. Ridgway.
1966. S e r o l o g i c a l evidence f o r i n b r e e d i n g
of Lahontan c u t t h r o a t t r o u t , Salmo c l a r k i
henshawi, i n Summit Lake, Nevada. C a l i f .
F i s h and Game 52 (3) :180-184.
Wheeler, S. S.
1969. The d e s e r t l a k e . Caxton P r i n t e r s ,
Caldwell, Idaho. 133 p.
PAIUTE TROUT
Salmo c l a r k i s e l e n i r i s
-TYPICAL MERISTIC CHARACTERS
S c a l e counts
l a t e r a l series
(two rows above l a t e r a l
line)
and above l a t e r a l l i n e
( o r i g i n of d o r s a l f i n
to lateral line)
c h a r a c t e r t o Snyder t h a t h e d e s c r i b e d -I'
s e l e n i r i s " a s a new s p e c i e s and became somewhat p o e t i c a l i n h i s s e l e c t i o n of a s p e c i f i c
a f a n c i f u l resemblance
name which suggested
of i t s evanescent t i n t s t o t h e l u n a r rainbow"
(Snyder 1934).
"...
150-180
33-40
Vertebrae
60-63
(mean 61.8)
G i l l r a k e rs
21-27
(mean 24)
P y l o r i c caecae
50-70
Basibranchial t e e t h
2-15
(Behnke 1960, personal d a t a from
s,pecimens taken from S i l v e r King
Creek, C a l i f o r n i a , 1933-1956)
SPECIES DESCRIPTION
The P a i u t e (sometimes s p e l l e d P i u t e )
t r o u t was d e s c r i b e d by Snyder (1933) from
above a barrier f a l l s i n t h e headwaters of
S i l v e r King Creek, Alpine County, C a l i f o r n i a .
S i l v e r King Creek i s t r i b u t a r y t o t h e
E a s t Fork of t h e Carson River of t h e Lahontan
b a s i n . Snyder recognized t h e a f f i n i t i e s and
d e r i v a t i o n of t h e P a i u t e t r o u t from 2. 2.
henshawi, the t r o u t n a t i v e t o t h e Lahontan
b a s i n . The absence of s p o t s on t h e body
seemed l i k e such a s t r i k i n g d i a g n o s t i c
Snyder's p u b l i c a t i o n , however, provided
l i t t l e d a t a on t h e taxonomic c h a r a c t e r s of
t h e P a i u t e t r o u t , p a r t i c u l a r l y concerning i t s
range of v a r i a b i l i t y and a n adequate comparison w i t h 2. c. henshawi. No published taxonomic
d a t a has appeared s i n c e t o supplement h i s
o r i g i n a l work, b u t a Master of A r t s t h e s i s by
Behnke (1960) and subsequent d a t a which h e has
accumulated r e v e a l s t h a t 2. 2. s e l e n i r i s has
n e a r l y i d e n t i c a l v a l u e s t o 2. 2. henshawi- i n
a l l of i t s m e r i s t i c c h a r a c t e r s . Data on 2. 5.
s e l e n i r i s which appear above a r e published
h e r e f o r t h e f i r s t time.
The g i l l r a k e r number i n d i c a t e s t h a t the
s e p a r a t i o n of 2. 2. s e l e n i r i s i n S i l v e r King
Creek from an a n c e s t r a l g. 5. henshawi occurred
a f t e r g. 2. henshawi had a t t a i n e d i t s ultimate
number of g i l l r a k e r s i n p l u v i a l Lake Lahontan
under l a c u s t r i n e s e l e c t i v e p r e s s u r e s , no more
than about 5,000 t o 8,000 y e a r s ago. The
P a i u t e t r o u t , t h e n , probably was n o t derived
from t h e p r i m o r d i a l t r o u t which invaded t h e
Lahontan basin, b u t developed i n s t e a d r a t h e r
r e c e n t l y , d i f f e r i n g from g: 2. henshawi only
i n s p o t t i n g p a t t e r n . Most l i k e l y t h e phylog e n e t i c s e p a r a t i o n of 2. 2. s e l e n i r i s from
S. 2. henshawi i n t h e Carson River drainage
occurred a f t e r t h e i s o l a t i o n of t h e v a r i o u s
s t o c k s of 5. 2. henshawi i n t h e Truckee,
-
Carson and Walker r i v e r systems by t h e desiccation of Lake Lahontan.
Even the absence of s p o t s on t h e body a s
a character t o d i f f e r e n t i a t e g. 5. s e l e n i r i s
from 5. 5. henshawi cannot be used a s a b s o l u t e l y
as
b e l i e v e d . Stephen Nicola,
C a l i f o r n i a Department of Fish and Game, c a r e fullyexamined 79 of t h e specimens of 2. 5.
s e l e n i r i s taken from S i l v e r King Creek i n
i-found
t h a t w h i l e 47 specimens had no
spots, 32 had from one t o n i n e s p o t s on t h e
body (s. Nicola, p e r s o n a l communication t o
R. Behnke, 5 June 1974).
m e n Snyder d e s c r i b e d t h e P a i u t e t r o u t
in 1933, he assumed t h a t i t had o r i g i n a t e d i n
Silver King Creek above Llewellyn F a l l s and
S
,
limited t o t h e known d i s t r i b u t i o n a t t h a t
time. But S i l v e r King Creek above Llewellyn
Falls was o r i g i n a l l y b a r r e n of f i s h ; i t had
been stocked by a sheepherder w i t h t r o u t taken
from lower S i l v e r King Creek i n 1912. Another
transplant above t h e f a l l s took p l a c e i n 1924.
The subsequent discovery i n 1946 of P a i u t e
trout i n Corral Valley and Coyote Valley, two
isolated t r i b u t a r i e s t o lower S i l v e r King
Creek, was a t t r i b u t e d t o a n e a r l y but: unknown
introduction by man, which may have occurred
as e a r l y a s t h e 1860's when Canadian loggers
worked i n the a r e a (Baugh 1973). Stephen
Nicola kindly provided t o Robert Behnke t h e
information on t h e s e t r a n s p l a n t s , w h i c h i s
filed i n t h e o f f i c e of t h e C a l i f o r n i a Department of Fish and Game, Sacramento, and taken
from statements made i n 1944 by M r . V i r g i l
Connell, a stockman who p a s t u r e d sheep i n t h e
Silver King watershed.
M r . Connellls s t a t e m e n t s r a i s e a q u e s t i o n
on the o r i g i n a l d i s t r i b u t i o n of P a i u t e t r o u t .
If the stream above Llewellyn F a l l s was devoid
of t r o u t p r i o r t o 1912, and i f t h e introduced
trout came from lower S i l v e r King Creek, t h e n
the o r i g i n a l range must have included t h e
Silver King drainage above some n a t u r a l b a r r i e r
which prevented i n t e r b r e e d i n g w i t h t h e t y p i c a l
Lahontan c u t t h r o a t s of t h e E a s t Carson River
SYs tem.
Four M i l e Canyon Creeks ( i s o l a t e d t r i b u t a r i e s t o S i l v e r King Creek); North Fork
Cottonwood Creek and Cabin Creek, Mono County;
Birchim Lake, Inyo County; and Delany Creek,
Yosemite N a t i o n a l Park, where t h e N a t i o n a l
Park S e r v i c e i s a t t e m p t i n g t o remove brook
t r o u t t o s u s t a i n the Paiute population.
STATUS
AND POPUIATION TRENDS
S i l v e r King Creek was c l o s e d t o f i s h i n g
above L l e w e l l y n F a l l s i n 1933, a f t e r 2. c.
s e l e n i r i s was d i s c o v e r e d t h e r e . But when
a n g l i n g r e s t r i c t i o n s were removed i n 1952 i t
was found t h a t P a i u t e t r o u t , l i k e most c u t t h r o a t
t r o u t l i v i n g i n s t r e a m s , was e a s i l y caught and
v u l n e r a b l e t o o v e r - e x p l o i t a t i o n . But i t was
t h e a p p a r e n t l y i n a d v e r t a n t s t o c k i n g of 5000
rainbow t r o u t above Llewellyn F a l l s by t h e
C a l i f o r n i a Department of F i s h and Game i n 1949
which d e a l t t h e f i n a l blow t o t h e P a i u t e t r o u t
a s a p u r e form i n S i l v e r King Creek. A common
f i s h e r y management p r a c t i c e a t t h a t t i m e was
t o "seed" headwater mountain streams w i t h
"new blood" i n t h e form of h a t c h e r y t r o u t f r y ,
even though evidence had long accumulated t o
demonstrate t h e w o r t h l e s s n e s s of such s t o c k i n g .
A f t e r t h e 1949 rainbow t r o u t s t o c k i n g ,
Lahontan c u t t h r o a t s were m i s t a k e n l y dropped
by a i r p l a n e i n t o W h i t e c l i f f Lake, which flows
i n t o B u l l Creek and j o i n s S i l v e r King Creek
j u s t above Llewellyn F a l l s .
I n 1957, i n v e s t i g a t o r s found h y b r i d f i s h
w i t h s p o t s above Llewellyn F a l l s and by 1963
they c o n s i d e r e d t h e s i l v e r King Creek populat i o n a h y b r i d swarm. P a i u t e t r o u t p o p u l a t i o n s
i n C o r r a l and Coyote Valleys had by 1963 a l s o
thoroughly h y b r i d i z e d w i t h rainbow t r o u t from
a n unknown i n t r o d u c t i o n ; h a l f the specimens
lacked b a s i b r a n c h i a l t e e t h , and g i l l r a k e r
numbers ranged from 19-24, v e r s u s 21-27 i n
pure P a i u t e t r o u t . These specimens a l s o
e x h i b i t e d a p r o f u s i o n of s p o t s on t h e body
(R. Behnke, p e r s o n a l n o t e s and d a t a ) .
F o r t u n a t e l y , p u r e P a i u t e t r o u t had been
i n t r o d u c e d and e s t a b l i s h e d i n t o f o r m e r l y
b a r r e n F l y V a l l e y , Four M i l e Canyon and North
Fork Cottonwood Creeks t o e n s u r e i t s perpetuation.
By t h e time Snyder d e s c r i b e d 5. 2. s e l e n &in
1933, t h e t r o u t below Llewellyn F a l l s
had thoroughly h y b r i d i z e d w i t h rainbdw t r o u t
(Behnke 1960). It would be i n t e r e s t i n g t o
know the d a t e of t h e f i r s t i n t r o d u c t i o n of
rainbow t r o u t , and of Lahontan c u t t h r o a t t r o u t ,
into the S i l v e r King drainage.
Treatment w i t h rotenone i n 1964 of S i l v e r
King Creek above Llewellyn F a l l s a t t e m p t e d t o
e l i m i n a t e h y b r i d s , and pure P a i u t e t r o u t were
r e - i n t r o d u c e d (MclLfee 1966, S t a l e y 1965). But
some h y b r i d s s u r v i v e d t h e poisoning because of
e x t e n s i v e beaver pond a r e a s which made thorough
treatment d i f f i c u l t and by 1968 f i s h w i t h s p o t s
on t h e body a g a i n occurred.
The p r e s e n t known d i s t r i b u t i o n of P a i u t e
trout c o n s i s t s e n t i r e l y of introduced populations which i n c l u d e t h o s e i n F l y v a l l e y and
The Threatened Trout Committee of t h e
C a l i f o r n i a Department of F i s h and Game, i n
l i g h t of t h e f a i l u r e of chemical t r e a t m e n t i n
S i l v e r King Creek, has i n s t i t u t e d a n a l t e r n a t i v e management p r a c t i c e of annual e l e c t r o f i s h i n g i n t h e c r e e k above Llewellyn F a l l s
w i t h s e l e c t i v e removal of f i s h which d i s p l a y
more t h a n f i v e s p o t s on t h e body. The
e f f i c a c y of t h i s t e c h n i q u e i s c u r r e n t l y being
t e s t e d (Ryan and Nicola, 1976).
The U. 6 . Department of t h e I n t e r i o r had
o f f i c i a l l y l i s t e d 5. 5. s e l e n i r i s a s a n
endangered s p e c i e s , b u t because of management
problems r e s u l t i n g from t h e "endangered"
c l a s s i f i c a t i o n (see c h a p t e r on 2. 2. stomias,
page 1 9 ) , t h e C a l i f o r n i a Department of F i s h
and Game p e t i t i o n e d t h e I n t e r i o r Department
The
t o change t h e s t a t u s t o "threatened."
o f f i c i a l change i n s t a t u s from "endangered"
t o "threatened" took p l a c e i n J u l y , 1975
(Federal R e g i s t e r 140 (37), 16 J u l y 1975).
A l l p r e s e n t pure populations of s e l f reproducing P a i u t e t r o u t occur i n s m a l l ,
i s o l a t e d environments, b u t t h e nucleus e x i s t s
to intensify restoration projects.
LIFE HISTORY
Some l i f e h i s t o r y information appears
i n McAfee (1966). D a r r e l Wong (1975) and
James Diana (1975) p r e s e n t more d e t a i l e d d a t a
based on s t u d i e s of t h e North Cottonwood
Creek population.
P a i u t e t r o u t a t t a i n a l e n g t h of o n l y 23
t o 25 cm i n small streams such a s the headw a t e r s of S i l v e r King Creek, but a r e known t o
r e a c h l e n g t h s of up t o 46 cm i n l a r g e r bodies
of water such a s Birchim Lake (McAfee 1966).
The most s i g n i f i c a n t l i f e h i s t o r y a t t r i b u t e of t h e P a i u t e t r o u t i n r e l a t i o n t o management must be implied from a knowledge of
i t s e v o l u t i o n a r y h i s t o r y . 5. 2. s e l e n i r i s
has been completely i s o l a t e d from o t h e r
s p e c i e s of f i s h f o r probably s e v e r a l thousand
years, ever since i t s separation, i n S i l v e r
King Creek, from a Lahontan c u t t h r o a t t r o u t
a n c e s t o r . The c u t t h r o a t i n o t h e r a r e a s of
t h e Lahontan b a s i n evolved w i t h a d i v e r s e
fauna of s e v e r a l s p e c i e s of minnows and
s u c k e r s , a w h i t e f i s h , and a s c u l p i n . S e l e c t i v e p r e s s u r e s c a n d i f f e r g r e a t l y between
p o p u l a t i o n s c o e x i s t i n g w i t h a d i v e r s i t y of
s p e c i e s and t h o s e developing i n i s o l a t i o n ,
w i t h t h e r e s u l t t h a t l i f e h i s t o r y and behavioral c h a r a c t e r i s t i c s of i s o l a t e d f i s h e s
may prevent them from c o e x i s t i n g s u c c e s s f u l l y
p i t h o t h e r s p e c i e s . It must be assumed t h a t
n t r a n s p l a n t of P a i u t e t r o u t w i l l s t a n d a
good chance of s u c c e s s only i n waters b a r r e n
of o t h e r f i s h e s .
HABITAT REQUIREMENTS AND LIMITING FACTORS
Although t h e a n c e s t r a l t r o u t of t h e
Lahontan b a s i n l i v e d a s a l a r g e , l a c u s t r i n e
p r e d a t o r i n p l u v i a l Lake Lahontan, t h e Paiute
t r o u t has evolved i n a s m a l l , c o l d stream
environment. S i n c e i t t h r i v e s a l s o i n
Birchim Lake, i t can be expected t h a t t h e
P a i u t e t r o u t can a d a p t s u c c e s s f u l l y t o v i r t u a l l y any s u i t a b l e t r o u t w a t e r s . The ultimate
l i m i t i n g f a c t o r , though, may be t h e presence
of o t h e r f i s h e s , p a r t i c u l a r l y t r o u t s .
Schneegas and P i s t e r (1967) and Ashley
(1970) have w r i t t e n h a b i t a t management plans
f o r the Paiute trout.
PROTECTIVE MEASURES
To i n s u r e p r o t e c t i o n of t h e upper S i l v e r
King Creek watershed, t h e Toiyabe National
F o r e s t and t h e S i e r r a P a c i f i c Power Company
t r a n s a c t e d a l a n d exchange i n 1971 which made
most of t h e watershed p u b l i c land. The U. S.
Marine Corps agreed t o d i s c o n t i n u e i t s use of
t h e watershed f o r s u r v i v a l t r a i n i n g i n 1963.
A f t e r t h e poisoning of S i l v e r King Creek t o
remove hybrids i n 1964, pure P a i u t e t r o u t were
r e i n t r o d u c e d . But hybrids reappeared and the
C a l i f o r n i a Department of Fish and Game i s
a t t e m p t i n g t o c o n t r o l them by annual e l e c t r o f i s h i n g . The c o n s t r u c t i o n of a b a r r i e r on Four
M i l e Canyon Creek i n 1972 w i l l h o p e f u l l y insure
t h e i s o l a t i o n of Paiute t r o u t there.
T r a n s p l a n t programs have e s t a b l i s h e d
s e v e r a l new p o p u l a t i o n s (see page 29).
The Threatened Trout Committee of t h e
C a l i f o r n i a Department of F i s h and Game
provides t h e s t r u c t u r e t o coordinate s t a t e
and f e d e r a l e f f o r t s t o p r o t e c t and enhance
t h e d i s t r i b u t i o n and abundance of t h i s t r o u t .
RECOMMENDATIONS
Pure populations of 2. 2. s e l e n i r i s no
longer e x i s t i n i t s n a t i v e w a t e r s . The extremel y l i m i t e d n a t u r a l d i s t r i b u t i o n and c a t a s t r o p h i c d e c l i n e i n abundance of such a f i s h may
make i t a m a t t e r o f common s e n s e n o t t o
r e s t r i c t restoration efforts t o the native
range. Although C a l i f o r n i a ' s Threatened
T r o u t Committee has n o t y e t formalized i t s
t h i n k i n g i n t h i s m a t t e r , t h e c u r r e n t view i s
t h a t S i l v e r King Creek and i t s t r i b u t a r i e s
down t o a p o i n t below t h e confluence of
Corral Valley Creek and North Fork Cottonwood
creek w i l l be t h e e x t e n t of i t s r e s t o r a t i o n
e f f o r t s , although p r o t e c t i o n of P a i u t e t r o u t
in Cabin Creek and Birchim Lake w i l l remain
in f o r c e a l s o (S. Nicola, p e r s o n a l communication t o R. Behnke)
.
The P a i u t e t r o u t could become a n i n t e g r a l
*art of t r o u t management i n mountain l a k e s i f
a brood s t o c k l a k e , s i m i l a r t o Heenan Lake
f o r 5. 2. henshawi propagation, were e s t a b lished, s i n c e many mountain l a k e s l a c k
adequate Spawning a r e a f o r t r o u t of t h e genus
salmo t o m a i n t a i n s e l f - r e p r o d u c i n g p o p u l a t i o n s ,
S u s t be s t o c k e d w i t h t r o u t f r y dropped
from a i r c r a f t . The p o t e n t i a l of S. c .
s e l e n i r i s , a s a r a r e and b e a u t i f u l t r o u t ,
l u r e h i k e r s t o more remote and l i t t l e - u s e d
areas of n a t i o n a l f o r e s t s could s e r v e a s a
"crowd d i s p e r s a l " t e c h n i q u e i n
f i s h e r y and w i l d e r n e s s management.
Streams w i t h n a t u r a l b a r r i e r s and s m a l l
lakes having p o t e n t i a l spawning t r i b u t a r i e s
but now h a r b o r i n g non-native t r o u t s should b e
considered f o r chemical t r e a t m e n t t o e l i m i n a t e
present t r o u t p o p u l a t i o n s and t o e s t a b l i s h
additional s e l f - p e r p e t u a t i n g p o p u l a t i o n s of
S.
seleniris.
- c.
AUTHORITIES
1. Robert Behnke
Dept. of F i s h e r y and W i l d l i f e Biology
Colorado S t a t e U n i v e r s i t y
Fort C o l l i n s , CO 80523
(taxonomic i n v e s t i g a t i o n s )
2.
Stephen Nicola, Chairman
Threatened Trout Committee
C a l i f o r n i a Dept. of F i s h and Game
1416 Ninth S t .
Sacramento, CA 95814
( p r o t e c t i o n and r e s t o r a t i o n programs)
3.
Philip Pister
407 W. Line S t .
Bishop, CA 93514
(data r e g a r d i n g i n t r o d u c e d p o p u l a t i o n s i n
North Cottonwood Creek and Birchim Lake)
REFERENCES
Ashley, R. R.
1970. H a b i t a t management p l a n , P i u t e t r o u t .
USDA F o r e s t S e r v i c e , Toiyabe Nat. For. 15 p.
Baugh, T.
1973. To s a v e a s p e c i e s .
7 (3) :24-26.
Nevada Outdoors
Behnke, R. J.
1960. Taxonomy of t h e c u t t h r o a t t r o u t o f
t h e Great Basin w i t h n o t e s on t h e rainbow
s e r i e s . M. A. T h e s i s , Univ. C a l i f o r n i a ,
Berkeley-.
98 p.
Dunham, D. K.
1968.. P r e l i m i n a r y survey a n a l y s i s of S i l v e r
King Creek h a b i t a t above Llewellyn F a l l s ,
A l i p i n e County, C a l i f o r n i a . U.S. For. Serv,
Toiyabe Nat. For. 1 0 p.
McAfee, W. R.
1966. P a i u t e c u t t h r o a t t r o u t . 3 A. J.
Calhoun (ed.), Inland F i s h e r i e s Management,
C a l i f . Dept. F i s h and Game, Sacramento.
p. 231-233.
Ryan, J. H., and S. J. Nicola.
1976. S t a t u s of t h e P a i u t z c u t t h r o a t t r o u t ,
Salmo c l a r k i s e l e n i r i s Snyder, i n C a l i f o r n i a . D r a f t Rep. of Threatened T r o u t Comm.,
C a l i f . Dept. F i s h and Game. 59 p.
Schneegas, E. R. and E. P. P i s t e r .
1967. P i u t e t r o u t h a b i t a t management p l a n .
USDA F o r e s t S e r v i c e , Inyo Nat. For. 30 p.
Snyder, J. 0.
1933. D e s c r i p t i o n of S a h o s e l e n i r i s , a
new C a l i f o r n i a t r o u t . Proc. C a l i f . Acad.
S c i . 20(11):471-472.
1934. A new C a l i f o r n i a t r o u t .
F i s h and Game 20(2) :105-112.
California
V e s t a l , E. H.
1947. A new t r a n s p l a n t of t h e P i u t e t r o u t
(Salmo c l a r k i s e l e n i r i s ) from S i l v e r King
Creek, A l p i n e County, C a l i f o r n i a . Califo r n i a F i s h and Game 33 (2): 89-96.
GILA TROUT
Salmo g i l a e
TIP1CA.L MERISTIC CHARACTERS
SPECIES DESCRIPTION
S c a l e counts
l a t e r a l series
(two rows above l a t e r a l
line)
and above l a t e r a l line
( o r i g i n of d o r s a l f i n
t o lateral l i n e )
135-165
Vertebrae
5 9 - 6 ~ ~
PylorZc caecae
25-46
(means 33-36)y
43-57
(mean 47.2)rl
Basibranchial t e e t h
~bsen&
Although a n a t i v e t r o u t was h i s t o r i c a l l y
known from t h e G i l a River b a s i n of New Mexico,
i t was n o t u n t i l t h i s t r o u t was on t h e brink
of e x t i n c t i o n t h a t i t was recognized a s d i s t i n c t and described a s a new s p e c i e s by R. R.
M i l l e r (1950).
29-38
-
L-Taxonomic d a t a from Behnke (1973) and
p e r s o n a l d a t a ; and from David (1976) .-/
d ~ e a values
n
f o r samples from four
l o c a l i t i e s range from 59.7 f o r Spruce Creek
specimens t o 61.7 f o r McKenna Creek specimens.
U v a l u e s from specimens from Main Diamond,
South Diamond and McKenna Creeks
d v a l u e s from specimens from Spruce
Creek
& / ~ b s e n ti n a l l New Mexico specimens
examined except t h o s e i n Spruce Creek.
Basibranchial t e e t h were a l s o p r e s e n t i n
t h r e e of f o u r specimens c o l l e c t e d from Verde
River drainage of Arizona i n 1888-89.
A problem w i t h providing a n adequate
diagnosis of Salmo g i l a e i s t h a t t h e o r i g i n a l
d e s c r i p t i o n i s based on a population i n t i n y ,
i n t e r m i t t e n t Main Diamond Creek and c e r t a i n l y
does n o t encompass t h e range of n a t u r a l v a r i a b i l i t y of t h i s t r o u t throughout i t s o r i g i n a l
range. M i l l e r (1972) considered the o r i g i n a l
range of t h e Gila t r o u t t o include t h e Verde
River sys tern of Arizona (where t h e n a t i v e
t r o u t i s now e x t i n c t ) . Four specimens c o l l e c t ed from Oak Creek, south of F l a g s t a f f , i n 1888
and 1889, and now i n t h e U. S. National
Museum, have t h e s p o t t i n g p a t t e r n t y p i c a l of
t h e s p e c i e s ( M i l l e r 1972, f i g . 5), but t h r e e
of t h e f o u r possess b a s i b r a n c h i a l t e e t h , a
c h a r a c t e r n o t previously reported i n $5.silae
i n t h e G i l a River b a s i n of New Mexico. Howe v e r , David (1976) found b a s i b r a n c h i a l t e e t h
in f o u r of 1 2 specimens of G i l a t r o u t from
Spruce Creek, a t r i b u t a r y of t h e San Francisco
River system of New Mexico.
A d i s t i n c t i v e f e a t u r e of S. g i l a e i s t h e
profuse p a t t e r n of small, irregularly-shaped
s p o t s , mainly above t h e lateral line on t h e
UTAH
I
COLORADO
/"3
~ i \ oRiver
I
Tucson
Salmo opoche
Map 4.
I
I
Kilometers
Indigenous distrLbution of S a h o g i l a e and Salmo apache.
body, onto t h e head, and on t h e d o r s a l and
caudal f i n s . The b a s i c c o l o r a t i o n i s yellowish
o r olive-yellow on t h e s i d e s of the body; a
f a i n t r o s e band may be p r e s e n t along t h e
l a t e r a l l i n e i n a d u l t s . A yellow c u t t h r o a t
mark i s p r e s e n t and t h e d o r s a l , a n a l and
p e l v i c f i n s a r e t i p p e d with w h i t e o r yellow.
-
River ( t h e n e x t d r a i n a g e west of t h e Verde
s y s tem) , were c o l l e c t e d by Mr. Gary Edward,
of t h e Arizona Department o f Game and Fish
and s e n t t o Robert Behnke f o r i d e n t i f i c a t i o n ,
Although t h e Sycamore Creek population has
hybridized w i t h rainbow t r o u t , enough of the
o r i g i n a l genotype remains t o i n d i c a t e t h a t
t h e n a t i v e t r o u t of Sycamore Creek had a
s p o t t i n g p a t t e r n t y p i c a l of S. gilae.
Salmo - i s
reputed t o have a unique
karyotype (number and morphology of chromosomes) which d i f f e r e n t i a t e s i t from a l l o t h e r
t r o u t s (R. R. M i l l e r , personal communication
t o R. Behnke). M r . Robert David, New Mexico
S t a t e U n i v e r s i t y , has s t u d i e d t h e chromosomes
of 2. gilae a £ter completion of h i s t h e s i s .
P r e l i m i n a r y a n a l y s i s i n d i c a t e s a karyotype
d i f f e r e n t from any o t h e r t r o u t (personal
communication t o R. Behnke).
Thus, 2. g i l a e was probably n a t i v e to
both t h e Verde and Agua F r i a d r a i n a g e s of
Arizona. Needham and Gard (1959) described
t r o u t from t h e Rio Yaqui of Mexico, a contiguous b a s i n w i t h t h e G i l a River, which
appears s i m i l a r t o 2. gilae.
Gila t r o u t which have hybridized w i t h
rainbow t r o u t a r e common i n many t r i b u t a r i e s
o f t h e upper G i l a River. They e x h i b i t e r r a t i c
s p o t t i n g and c o l o r a t i o n , h i g h e r v e r t e b r a l and
c a e c a l counts and lower s c a l e counts.
Unfortunately, t h e almost complete e l b .
i n a t i o n of both S. g i l a e and 2. apache from
t h e i r n a t i v e ranges before e i t h e r o f these
s p e c i e s was s t u d i e d , prevents a b e t t e r unders t a n d i n g of t h e i r o r i g i n a l d i s t r i b u t i o n .
DISTRIBUTION
L i t t l e information e x i s t s t o accurately
d e f i n e t h e o r i g i n a l d i s t r i b u t i o n of t h e G i l a
t r o u t . M i l l e r (1950) documented i t s occurr e n c e throughout t h e upper Gila River watershed downstream t o t h e town of C l i f f , New
Mexico, i n 1896, b u t i t r e p u t e d l y was a b s e n t
from t h e San F r a n c i s c o d r a i n a g e of New Mexico
and Arizona. M i l l e r (1972) evaluated museum
specimens c o l l e c t e d from t h e Verde d r a i n a g e ,
Arizona, a t r i b u t a r y t o t h e S a l t River of
t h e G i l a R i v e r b a s i n , and pronounced them t o
be Salmo g i l a e . The p r e s e n t population of
G i l a t r o u t i n Spruce Creek, New Mexico, a
headwater t r i b u t a r y i n t h e San Francisco
drainage, i s a t t r i b u t e d t o an introduction
i n 1905 ( M i l l e r 1950).
The zoogeography of t h e d i s t r i b u t i o n of
S. ~ i l a ei s puzzling. One would expect t h a t
S. apache, t h e n a t i v e t r o u t i n t h e headwaters
o f t h e S a l t River system, should a l s o be t h e
t r o u t n a t i v e t o t h e Verde d r a i n a g e of Arizona.
And i f S. g i l a e once had d i r e c t communication
from t h e upper G i l a b a s i n of New Mexico w i t h
t h e Verde d r a i n a g e of Arizona, why were no
remnant populations discovered i n t h e San
Francisco River system? This d i s t r i b u t i o n a l
enigma i s f u r t h e r compounded by t h e f a c t t h a t
t h e only known museum specimens of n a t i v e
t r o u t from t h e San Francisco River system
(K. P. Creek, Arizona) have t h e t y p i c a l s p o t t i n g p a t t e r n of 2. apache ( M i l l e r 1972, f i g .
4).
-
I n 1975, t r o u t specimens from Sycamore
Creek, Arizona, a t r i b u t a r y t o t h e Agua F r i a
,
P r e s e n t l y , pure o r e s s e n t i a l l y pure
populations a r e known from Main Diamond,
South Diamond and McKenna Creeks, New Mexico.
The Spruce Creek population i n t h e San Franc i s c o drainage i s a t t r i b u t e d t o an e a r l y
i n t r o d u c t i o n , b u t t h e lower number of vertebrae,
h i g h e r number of p y l o r i c caecae and t h e report
o f b a s i b r a n c h i a l t e e t h i n specimens from
t h i s population i n d i c a t e t h a t Spruce Creek
t r o u t a r e w e l l - d i f f e r e n t i a t e d from o t h e r
S. ~ i l a ei n New Mexico. This might be cons t r u e d a s evidence supporting t h e indigenous
occurrence of S, g i l a e i n t h e San Francisco
drainage. F u r t h e r support of such n a t i v e
d i s t r i b u t i o n i s given by t h e former occurrence
o f S. a i l a e i n Eagle Creek, t h e n e x t major
t r i b u t a r y t o t h e G i l a River west of t h e San
F r a n c i s c o River (Mulch and Gamble 1956).
David (1976) discovered a population of pure
S. g i l a e i n I r o n Creek, an i s o l a t e d t r i b u t a r y
t o t h e Middle Fork of t h e G i l a River.
-
A c o o p e r a t i v e p r o j e c t between t h e U. S.
F o r e s t S e r v i c e , New Mexico Department o f Game
and F i s h , and New Mexico S t a t e U n i v e r s i t y
introduced G i l a t r o u t from Main Diamond
Creek i n t o McKnight Creek of t h e Mimbres
River b a s i n i n 1970 and 1972, a f t e r construct i o n o f a b a r r i e r and e l i m i n a t i o n of a sucker
population. These t r o u t have s u c c e s s f u l l y
reproduced (R. David and D o u g l a s ' J e s t e r , New
Mexico S t a t e U n i v e r s i t y , p e r s o n a l communicat i o n t o R. Behnke)
.
Another p r o j e c t t r a n s p l a n t e d 89 Gila
t r o u t from Main Diamond Creek i n t o b a r r e n
Sheep C o r r a l Creek, a t r i b u t a r y t o S a p i l l o
Creek i n , t h e Gila drainage, New Mexico.
stream improvement devices were
i n t o Sheep Corral Creek, t h e problem
of l i v e s t o c k overgrazing remains and t h e
degraded h a b i t a t has had no chance t o r e c o v e r .
A 1975 sunrey of Sheep C o r r a l Creek found 15
trout from t h e 1972 t r a n s p l a n t , b u t no s i g n
,,isted t h a t s u c c e s s f u l r e p r o d u c t i o n had
Probably 2. g i l a e cannot become
,,curred.
,,tablished i n Sheep C o r r a l Creek u n t i l t h e
grazing problem i s c o r r e c t e d (R. David,
personal communication t o R. Behnke).
The Arizona Game and F i s h Department
transplanted 5. gilae from Main Diamond Creek,
New Mexico i n t o Gap Creek, a b a r r e n t r i b u t a r y
,,f the Verde d r a i n a g e i n 1974, i n a n a t t e m p t
-to r e s t o r e t h i s s p e c i e s t o t h e Verde system.
A more ambitious program t o r e s t o r e t h e Gila
trout t o i t s h i s t o r i c range i n Arizona was
delayed by t h e l o s s of a h a t c h e r y brood s t o c k
in 1974 (Gary Edwards, Arizona Game and F i s h
Department, p e r s o n a l communication t o R.
~ehnke)
.
STATUS AND POPULATION TREND
Miller (1950, 1961) described t h e former
abundance and r a p i d d e c l i n e t o almost e x t i n c tion of 2. gilae. H y b r i d i z a t i o n throughout
the upper G i l a b a s i n r e s u l t i n g from t h e i n t r o duction of rainbow t r o u t was s o e x t e n s i v e
that by 1950 t h e v e r y few pure populations of
Gila t r o u t which remained were a l l i s o l a t e d
by b a r r i e r s i n small headwater streams. Subsequent r e - i n t r o d u c t i o n programs i n New
Mexico and Arizona have met w i t h modest success
and t h e d i s t r i b u t i o n and abundance of t h i s
rare t r o u t have i n c r e a s e d i n r e c e n t y e a r s .
Salmo g i l a e i s o f f i c i a l l y recognized a s
an endangered s p e c i e s under t h e Endangered
Species 'Act of 1973.
LIFE HISTORY
Two Master of Science t h e s e s have been
prepared on t h e G i l a Trout of Main Diamond
Creek (Regan 1964, Hanson 1971). Although
these s t u d i e s p r e s e n t d e t a i l e d information on
age, growth, food h a b i t s and f e c u n d i t y of t h e
trout and on p h y s i c a l , chemical and b i o l o g i c a l
parameters of t h e w a t e r , t h i s information
reveals b u t c e r t a i n l i f e h i s t o r y c h a r a c t e r i s tics a s determined by t h e h a r s h environment
of Main Diamond Creek. These s t u d i e s a r e of
limited v a l u e i n p r e d i c t i n g a d a p t a b i l i t y t o
new waters except t o i n d i c a t e t h a t a t r o u t
which c a n t h r i v e i n Main Diamond Creek i s
l i k e l y t o do w e l l i n almost any t r o u t h a b i t a t ,
a s long a s no o t h e r f i s h a r e p r e s e n t . The
growth p o t e n t i a l of 2. & almost c e r t a i n l y
i s g r e a t e r than t h e 23 cm maximum s i z e i t
a t t a i n s i n Main Diamond Creek.
Most probably, t h e o r i g i n a l 5. g i l a e
found i n t h e upper G i l a b a s i n d i d n o t c o n s i s t
of a s i n g l e homogeneous population, b u t
i n s t e a d was composed of s e v e r a l d i s c r e t e
s t o c k s i n t h e s m a l l e r t r i b u t a r i e s and probably
a n o t h e r s t o c k u t i l i z i n g t h e main r i v e r and
l a r g e r t r i b u t a r i e s ; these separate stocks
probably possessed s l i g h t l y d i f f e r i n g l i f e
h i s t o r y c h a r a c t e r i s t i c s . The assumption of
d i s c r e t e populations and g e n e t i c h e t e r o g e n e i t y
i s supported by t h e taxonomic d i f f e r e n c e s
found between e x i s t i n g p o p u l a t i o n s , p a r t i c u l a r l y when Spruce Creek specimens a r e compared
w i t h o t h e r samples of 5. gilae.
HABITAT REQUIREMENTS AND LIMITING FACTORS
P r e s e n t 5. g i l a e populations appear s u f f i c i e n t l y a d a p t a b l e t o l i v e i n any waters
s u i t a b l e f o r any s p e c i e s of t r o u t , even though
o r i g i n a l l y t h i s s p e c i e s probably c o n s i s t e d of
d i s j u n c t populations with d i f f e r i n g e c o l o g i c a l
s p e c i a l i z a t i o n s . A major l i m i t i n g f a c t o r ,
though, remains t h e presence, i n p o t e n t i a l
G i l a t r o u t h a b i t a t , of o t h e r s p e c i e s of
t r o u t ; rainbow t r o u t h y b r i d i z e w i t h 5. g i l a e
and brook and brown t r o u t compete w i t h i t
f o r food and space. Any stream p r e s e n t l y
h o l d i n g brook, brown, o r rainbow t r o u t can
provide s u i t a b l e h a b i t a t f o r 2. g i l a e a f t e r
a l l e x o t i c t r o u t s a r e e l i m i n a t e d and prevented
from re-invasion.
PROTECTIVE MEASURES
Main Diamond, South Diamond, McKenna,
I r o n and Spruce Creeks a r e i n t h e G i l a Wilderness Area of t h e G i l a National F o r e s t ; thus
they a r e endowed with some e x t r a l e g a l prot e c t i o n from h a b i t a t degradation.
The "endangered" s t a t u s g r a n t e d t h e G i l a
t r o u t under t h e Endangered Species Act of
1973 p r o h i b i t s i t s "taking" o r "harassment, "
but p r o h i b i t i n g a n g l i n g f o r a n endangered
t r o u t , p a r t i c u l a r l y i n remote a r e a s , may n o t
be r e l e v a n t t o t h e p r o t e c t i o n of t h e s p e c i e s
except i n a n e g a t i v e way, s i n c e any l a r g e s c a l e r e s t o r a t i o n e f f o r t must be based on
i n t r o d u c t i o n i n t o p u b l i c waters. Subsequent
c l o s u r e of such w a t e r s t o a n g l i n g can c r e a t e
unfavorable response t o such p r o j e c t s and
i n h i b i t r e a l i z a t i o n of t h e d e s i r e d goal. Howe v e r , due t o t h e extreme r a r i t y of 2. g i l a e ,
i t may n o t be wise t o remove t h e s p e c i e s from
t h e endangered l i s t u n t i l the L i t t l e Creek
r e s t o r a t i o n p r o j e c t has been s u c c e s s f u l l y
completed.
AUTHORITIES
1.
McKnight Creek has s u f f e r e d h a b i t a t
degradation from l i v e s t o c k overgrazing. The
U. S. Forest S e r v i c e i n i t i a t e d c o r r e c t i v e
measures i n 1975 and a l s o plans t o i n s t i t u t e
grazing c o n t r o l i n the Sheep Corral watershed i n 1976 (Douglas J e s t e r , personal communication t o R. Behnke).
Members :
Bruce Anderson
U. S. F o r e s t Service, Gila Natl. Forest
The G i l a t r o u t recovery team has d r a f t e d
a n o u t l i n e of a G i l a t r o u t recovery p l a n
(January 19, 1976). Included i n t h e p l a n is
a re-introduction of 5 ~ i l a ei n t o L i t t l e
Creek a f t e r c o n s t r u c t i o n of a b a r r i e r and
e l i m i n a t i o n of hybrids.
Bruce Rosenlund
U. S . Fish and W i l d l i f e Service
William S i l v e y
Arizona Game and Fish Department
2.
The Arizona Department of Game and Fish
plans t o r e - e s t a b l i s h a brood s t o c k of Gila
t r o u t f o r i n t r o d u c t i o n s i n t o the Verde and,
perhaps, Agua F r i a drainages (G. Edwards,
personal communication t o R. Behnke).
S e c t i o n 7 of t h e Endangered Species Act
of 1973 d i r e c t s a l l f e d e r a l agencies t o
c a r r y o u t programs f o r conservation of endangered and threatened s p e c i e s and t o prev e n t any of t h e i r a c t i v i t i e s from jeopardizing
t h e continued e x i s t e n c e of these s p e c i e s .
3.
-
Robert David
Dept. of Fishery and W i l d l i f e Science
New Mexico S t a t e University
Las Cruces, NM 88003
(graduate t h e s i s on taxonomy of
S. gilae
John Hubbard
New Mexico Game and Fish Department
S t a t e Capitol
Santa Fe, NM 87503
( i n charge of endangered and threatened
s p e c i e s program i n New Mexico)
5.
The population i n South Diamond Creek
e x h i b i t s t h e most uniform appearance of a l l
known e x i s t i n g populations of S. g i l a e ; a s
t h e most i d e a l r e p r e s e n t a t i v e of t h e s p e c i e s ,
a t l e a s t some f u t u r e t r a n s p l a n t s should be
made from t h i s population.
Robert David's r e s e a r c h has revealed
some populations of t r o u t which, although
s l i g h t l y hybridized, e x h i b i t a predominant
S. g i l a e p3anotype. Such populations should
b e p r o t e c t e d a g a i n s t f u t u r e i n t r o d u c t i o n s of
non-native t r o u t .
Robert Behnke
Dept. of Fishery and W i l d l i f e Biology
Colorado S t a t e University
F o r t C o l l i n s , CO 80521
(taxonomic i n v e s t i g a t i o n s )
4.
I f t h e L i t t l e Creek r e s t o r a t i o n p r o j e c t
meets w i t h success, t h e Gila t r o u t should be
changed i n s t a t u s from "endangered" t o
"threatened."
This change w i l l f a c i l i t a t e
management of t h e s p e c i e s and s t i m u l a t e
f u r t h e r t r a n s p l a n t s i n t o p u b l i c waters.
Gila Trout Recovery Team
Carl Schmit t , Leader
New Mexico Game and Fish Department
S t a t e Capitol
Santa Fe, NM 87503
Douglas J e s t e r
Dept. of Fishery and W i l d l i f e Science
New Mexico S t a t e University
Las Cruces, NM 88003
(long involvement w i t h Gila t r o u t projects,
f i r s t with New Mexico Game and Fish Dept.,
presentliy a s f a c u l t y member a t NMSU)
6.
Paul Turner
Dept. of Fishery and W i l d l i f e Science
New Mexico S t a t e University
Las Cruces, NM 88003
(cooperative p r o j e c t s with U. S. Forest
Service and New Mexico Game and Fish
Department)
REFERENCES
Behnke, R. J 1970. New i n f o r m a t i o n on G i l a t r o u t , Salmo
Rare and endangered s p e c i e s r e p o r t .
colorado Cooperative F i s h e r y U n i t , Colorado S t a t e U n i v e r s i t y , F t . C o l l i n s , 1 2 p.
(mime01
&.
-73.
G i l a t r o u t , Salmo g i l a e .
Endangered
s ~ e c i e sr e p o r t , prepared f o r U.S. F i s h and
-.
w i l d l i f e S e r v i c e , Region 11, Albuquerque,
N.M.
5 p.
(mimeo)
1961. Man and t h e changing f i s h f a u n a of
t h e American Southwest. Pap. Mich. Acad.
S c i . , A r t s , L e t t e r s 46:365-404.
1972. C l a s s i f i c a t i o n of t h e n a t i v e t r o u t s
o f Arizona w i t h t h e d e s c r i p t i o n o f a
new s p e c i e s , Salmo apache. Copeia 3:401422.
Mulch, E. D. and W. C. Gamble.
1956. Game f i s h e s o f Arizona. Arizona
Game and F i s h Department, Phoenix. 19 p.
David, R. E.
1976. Taxonomic a n a l y s i s of G i l a and G i l a x
rainbow t r o u t i n s o u t h w e s t e r n New Mexico.
M.S. t h e s i s , New Mexico S t a t e U n i v e r s i t y ,
Las Cruces, N.M.
36 p.
Needham, P. R. and R. Gard.
1959. Rainbow t r o u t i n C a l i f o r n i a and
Mexico w i t h n o t e s on t h e c u t t h r o a t s e r i e s .
Univ. of C a l i f . Publ. 2001. 67(1): 124 p.
Hanson, J. N 1971. I n v e s t i g a t i o n s on G i l a t r o u t , Salmo
-Miller,
i n s o u t h w e s t e r n New Mexico.
M. S. T h e s i s , New Mexico S t a t e U n i v e r s i t y ,
Las Cruces. 44 p .
Regan, D.
1964. Ecology of t h e G i l a t r o u t (Salmo
g i l a e ) i n Main Diamond Creek, New Mexico.
M. S. T h e s i s , Colorado S t a t e Univ., F t .
C o l l i n s . 5 7 p.
Miller, R. R.
1950. Notes on t h e c u t t h r o a t and rainbow
t r o u t w i t h t h e d e s c r i p t i o n o f a new
s p e c i e s from t h e G i l a R i v e r , New Mexico.
Occ. Pap. Mus. 2001. Univ. Mich. 529. 42 p.
1966. Ecology of G i l a t r o u t i n Main Diamond
Creek, New Mexico. U. S. F i s h and Wildl i f e S e r v i c e , Tech. Pap. S p o r t F i s h . 5 .
24 p.
ARIZONA NATIVE TROUT
Salmo apache
-
TYPICAL MERISTIC CHARACTERS
S c a l e counts
l a t e r a l series
(two rows above l a t e r a l
lines)
and above l a t e r a l l i n e
( o r i g i n of d o r s a l f i n
to lateral line)
133-172
(mean 146-158)
32-40
(mean 34-36)
Vertebrae
58-61
(mean 59.5-60)
P y l o r i c caecae
21-41
(mean 26.732.9)
Basibranchial t e e t h
Vestigial
SPECIES DESCRIPTION.
P y l o r i c caecae counts a r e among t h e
lowest of American t r o u t s ; basibranchial
t e e t h a r e v e s t i g i a l , with only f i v e t o 10
percent of t h e specimens of some populakions
possessing t h e s e t e e t h (Behnke 1970, 1973,
personal d a t a ) .
The b a s i c c o l o r a t i o n of Salmo apache
resembles t h a t of 5. g i l a e , with olive-yellow
t o golden-yellow on t h e s i d e s and v e n t r a l
region, a yellow c u t t h r o a t mark and w h i t i s h
t i p s on t h e d o r s a l , p e l v i c and a n a l f i n s .
While 2. apache l a c k s t h e rose-red l a t e r a l
band t y p i c a l of 2. -,
the s p o t t i n g p a t t e r n
c o n s t i t u t e s t h e most pronounced phenotypic
d i f f e r e n c e between t h e two t r o u t s . 2. apache
d i s p l a y s l a r g e r roundish o r oblong s p o t s ,
s i m i l a r t o i n t e r i o r c u t t h r o a t t r o u t s , over
t h e s i d e s of the body, onto t h e top of the
head and on t h e d o r s a l , caudal and adipose
f i n s (Miller 1972, f i g . 2). S. apache typically
possesses t h e l a r g e s t d o r s a l T i n of any
American t r o u t .
The unique karyotype of 2. apache shows
56 chromosomes w i t h 106 arms, and miy b e
derived from a c u t t h r o a t t r o u t - l i k e ancestor
(Miller 1972).
DISTRIBUTION
Cope and Yarrow (1875) f i r s t recorded
t r o u t i n the White River, Arizona ( i n the
headwaters of t h e S a l t River system of the
Gila River Basin) i n 1873, and r e f e r r e d t o
them a s a v a r i e t y of t h e Colorado River cutt h r o a t t r o u t . Jordan and Evermann (1896)
r e f e r r e d t o t h e t r o u t i n t h e headwaters of
t h e L i t t l e Colorado River i n Arizona a l s o as
t h e Colorado River c u t t h r o a t . When M i l l e r
(1950) described 2. g i l a e , he a l s o mentioned
n a t i v e t r o u t i n t h e headwaters of t h e East
Fork of t h e White River i n Arizona and prov i s i o n a l l y included them with t h e G i l a trout
a s 2. g i l a e . A f t e r f u r t h e r study and examinat i o n of many more specimens M i l l e r became
convinced of t h e uniqueness of t h i s t r o u t and
described i t a s a new s p e c i e s , Salmo apache
(Miller 1972).
By t h i s time, t h e range of S. apache had
been s o diminished t h a t t h e o r i g i n a l
Was impossible t o determine w i t h
certainty. M i l l e r (1972) considered i t s
native range t o i n c l u d e t h e upper S a l t River
system of Arizona (Black and White River
drainages) and t h e headwaters of t h e L i t t l e
River. A museum specimen t a k e n i n
1904 from K. P. Creek, a t r i b u t a r y of t h e
Blue River of t h e San Francisco d r a i n a g e of
Arizona, shows s p o t t i n g p a t t e r n s c h a r a c t e r i s t i c
of 2. apache and n o t 5. Rilae ( M i l l e r 1972,
f i g . 4 ) . Perhaps both s p e c i e s were n a t i v e
to the San Francisco drainage of Arizona, b u t
in t h i s case i t would be expected t h a t h y b r i d i ,,tion between them would have produced a n
array of i n t e r g r a d i n g populations.
The p r e s e n t known l i a t u r a l d i s t r i b u t i o n of
Ord Creek, F i r e b o x Creek,
S . apache includes:
-Deep
Creek, and headwaters of t h e E a s t Fork
of the White River; t h e upper Bonito Creek
rntershed, a t r i b u t a r y t o t h e Black River.
dl of t h e s e streams are on t h e F o r t Apache
Indian Reservation. The o n l y known p o p u l a t i o n
of 5. apache i n t h e L i t t l e Colorado River
basin e x i s t s i n Paddy Creek, between t h e towns
of Alpine and Nutrioso, Arizona, n e a r t h e New
Mexico border. A survey conducted i n 1967
by John Anderson, U.S. F i s h and W i l d l i f e
Service b i o l o g i s t , and Robert Behnke d e t e r mined t h a t r e c e n t l y introduced brook t r o u t
had become abundant i n Paddy Creek. Thus,
the outlook f o r t h e p e r p e t u a t i o n of t h e o n l y
known population of 2. apache i n t h e L i t t l e
Colorado River b a s i n a p p e a r s d o u b t f u l .
STATUS
Even though 2. apache possesses many
d i s t i n c t i v e c h a r a c t e r s i n c l u d i n g a unique
chromosome complement, no g e n e t i c b a r r i e r s
e x i s t a g a i n s t h y b r i d i z a t i o n w i t h rainbow o r
c u t t h r o a t t r o u t . The i n t r o d u c t i o n of rainbow
t r o u t i n t o w a t e r s of t h e White Mountains of
Arizona began h y b r i d i z a t i o n which s p r e a d
throughout t h e watersheds u n t i l o n l y remnant
pure populations of 2
. apache p e r s i s t e d i n a
r e l a t i v e l y few headwater a r e a s . Due t o t h i s
p r e c a r i o u s s i t u a t i o n , t h e U. S. Department
of t h e I n t e r i o r l i s t e d t h e Arizona t r o u t a s
endangered. But t h e endangered s t a t u s i n t e r f e r e d w i t h management and r e s t o r a t i o n e f f o r t s
and p r o h i b i t e d a n g l i n g (Christmas Tree Lake
on t h e F o r t Apache I n d i a n Reservation was
c o n s t r u c t e d and stocked with 2. apache f o r
use a s a n a t i v e t r o u t f i s h e r y ) , s o t h e s t a t u s
of 5. apache was o f f i c i a l l y changed from
"endangered" t o "threatened" (Federal R e g i s t e r
40 (137), 16 J u l y 1975).
While '2.apache has been v i r t u a l l y elimi n a t e d from i t s n a t i v e range, i t h a s survived
i n g r e a t e r numbers than 2. g i l a e . I n some
streams, such a s upper Ord Creek, g. apache
had been found t o c o e x i s t i n good abundance
with b o t h brown t r o u t and brook t r o u t . But
1974 e l e c t r o f i s h i n g i n Ord Creek showed brook
t r o u t t o be dominant and Arizona t r o u t , rare
(Ron Gumtow, personal communication t o
Robert Behnke, 2 October 1975).
LIFE HISTORY
As Miller (1972) pointed o u t , almost
nothing i s known of t h e l i f e h i s t o r y of
S. apache except f o r t h e s i g n i f i c a n t f a c t t h a t
i t s r e p r o d u c t i v e season and spawning behavior
must b e s u f f i c i e n t l y s i m i l a r t o rainbow t r o u t
t o permit h y b r i d i z a t i o n . Not a l l S. apache
populations a r e completely i s o l a t e d from
introduced t r o u t s . But w h i l e brook t r o u t ,
brown t r o u t , rainbow t r o u t , and rainbow X
S . apache h y b r i d s have replaced pure 5. apache
i n l a r g e r streams a t lower e l e v a t i o n s and i n
d i s t u r b e d h a b i t a t , S. apache h a s been a b l e t o
s u r v i v e w i t h brook t r o u t and brown t r o u t i n
Ord Creek and has p e r s i s t e d i n t h e headwaters
of t h e E a s t Fork of t h e White River and i n
t h e upper Bonito Creek watershed w i t h o u t prot e c t i o n by a b s o l u t e p h y s i c a l b a r r i e r s o r
from i n t r o d u c t i o n s of non-native t r o u t s .
Such s i t u a t i o n s resemble examples o f n a t i v e
c u t t h r o a t t r o u t maintaining t h e i r i n t e g r i t y
i n undisturbed headwater a r e a s where they
possess t h e most f i t genotypes f o r c o l d e r
waters and a s s o c i a t e d environmental c o n d i t i o n s .
D i s r u p t i o n and d e g r a d a t i o n of p r i s t i n e headwater environments t y p i c a l l y l e a d t o h y b r i d i z a t i o n w i t h rainbow t r o u t and/or replacement
by brown t r o u t o r brook t r o u t .
-
S . apache has been propagated a t t h e
sterl?ng Springs Hatchery, Arizona, and a
population has been e s t a b l i s h e d i n Christmas
Tree Lake, a s p o r t f i s h i n g l a k e c r e a t e d
specifically f o r t h i s species' restoration
on the P o r t Apache I n d i a n Reservation. The
Sterling Springs Hatchery is under r e n o v a t i o n
and a new brood s t o c k i s c u r r e n t l y being
established ( J o e Stone, p e r s o n a l communication
to Robert Behnke). The propagation and
reintroduction program f o r 2. apache conducted
by the Arizona Department of Game and Fish
has r e s u l t e d i n t h e e s t a b l i s h m e n t of new
Stream populations i n Grant, Home, Mineral,
and North Canyon Creeks and streams on .Graham
Mountain (Robert J a n t z e n , D i r e c t o r , Arizona
of Game and F i s h , l e t t e r t o Lynn
Greenwalt, D i r e c t o r , U. S. F i s h and W i l d l i f e
Service; J o e S t o n e , personal communication
to Robert Behnke)
.
AND POPULATION TREND
-
The growth p o t e n t i a l of S. apache remains
unknown, b u t t h e l a r g e s t specimen known from
Christmas Tree Lake, a s p e n t female, measured
48.8 cm and weighed 0.9 kg (Ron Gumtow,
p e r s o n a l communication t o Robert Behnke).
Ken Harper (Arizona Cooperative Fishery
Unit, USDI, 210 B i o l o g i c a l Sciences E a s t ,
U n i v e r s i t y of Arizona, Tucson, Arizona, 85721)
i s conducting g r a d u a t e r e s e a r c h t o determine
t h e e f f e c t s of logging on 2. apache i n t h e
Bonito.Creek watershed. This p r o j e c t , i n i t i a ,
t e d i n 1974, i s due f o r completion i n 1976.
HABITAT REQUIREMENTS AND LIMITING FACTORS
The i n t r o d u c t i o n of non-native t r o u t s
may n o t pose a s s e v e r e a t h r e a t t o 2. apache
a s it does t o 2. g i l a e i n cold headwater
streams a s long a s t h e i n t e g r i t y of t h e
h a b i t a t i s n o t v i o l a t e d . The complete r e p l a c e ment of %. apache a t lower e l e v a t i o n s and i n
d i s t u r b e d a r e a s demonstrates t h a t t h i s
s p e c i e s i s placed a t a competitive disadvantage i n such s i t u a t i o n s . The e n t i r e upper
Bonito Creek watershed, which c o n t a i n s t h e
most abundant populations of 2. apache, i s
c u r r e n t l y being logged. While g u i d e l i n e s
f o r h a b i t a t p r o t e c t i o n have been provided t o
t h e l o g g i n g o p e r a t i o n , they have no l e g a l
s t a n d i n g and some damage t o t h e stream has
a l r e a d y occurred (Richard Baldes and Ron
Gumtow, p e r s o n a l communication t o Robert
Behnke). The impact. of logging on t h e Bonito
Creek watershed and on 5. apache i s under
study, but data s u f f i c i e n t f o r basing forecasts a r e not yet available.
PROTECTIVE MEASURES
The Apache I n d i a n T r i b e h a s c l o s e d t h e
waters of Ord Creek t o f i s h i n g i n o r d e r t o
p r o t e c t t h e Arizona t r o u t .
The O f f i c e of Endangered S p e c i e s , U. S.
Department o f t h e I n t e r i o r , l i s t s 2. apache
a s a t h r e a t e n e d s p e c i e s (Federal R e g i s t e r
40 (137), 16 J u l y 1975).
The Arizona Department of Game and F i s h
has propagated %. apache a t t h e i r S t e r l i n g
Springs h a t c h e r y .from brood s t o c k developed
from Ord Creek t r o u t . At: l e a s t f o u r new
s t r e a m populations have been e s t a b l i s h e d .
The brood s t o c k was l o s t i n 1974 b u t t h e
h a t c h e r y is undergoing r e n o v a t i o n and a new
brood s t o c k i s b e i n g e s t a b l i s h e d (Gary Edwards,
Joe Stone, p e r s o n a l communications t o Robert
Behnke)
.
.
Bruce Rosenlund (U. S F i s h and W i l d l i f e
S e r v i c e , Alchesay-Williams National F i s h
Hatchery, W h i t e r i v e r , Arizona) h a s been cond u c t i n g d i s e a s e and p a r a s i t e s t u d i e s on 2.
apache t o determine t h e presence of f i s h
pathogens which could be s e r v i n g a s l i m i t i n g
f a c t o r s t o endangered populations i n t h e
w i l d , and t o determine t h e f e a s i b i l i t y of
t r a n s f e r r i n g endangered f i s h t o a h a t c h e r y
f o r propagation.
RECOMMENDATIONS
The Apache I n d i a n t r i b e h a s , i n t h e past,
demonstrated a s i n c e r e i n t e r e s t i n perpetua t i n g t h e Arizona t r o u t , but t h e r e c r e a t i o n a l
r e s o u r c e s of t h e r e s e r v a t i o n a r e nonetheless
a business e n t e r p r i s e and h e r e t o f o r e t h e
t o u r i s t f i s h e r y h a s been based mainly on
s t o c k i n g g r e a t numbers of rainbow t r o u t ,
p a r , t i c u l a r l y i n a s e r i e s of r e c r e a t i o n a l
l a k e s c r e a t e d on t h e r e s e r v a t i o n .
Ronald Gumtow, b i o l o g i s t w i t h t h e U. S .
F i s h and W i l d l i f e Service, and a d v i s o r on
f i s h e r i e s management t o t h e t r i b e , s t r e s s e s
a g r e a t l y expanded emphasis on t h e use of
S. apache i n s p o r t f i s h e r i e s management on
r e s e r v a t i o n w a t e r s i n t h e f u t u r e . The former
endangered s t a t u s of 2. apache p r o h i b i t e d
a n g l i n g and voided any economic g a i n s t o the
t r i b e from t h e p o t e n t i a l f i s h i n g i n Christmas
Tree Lake. Now t h a t t h e s t a t u s of g. apache
h a s been changed from endangered t o threatened,
t h e l a k e can be opened t o fishermen ( f o r a
f e e ) and s i m i l a r f i s h e r i e s f o r 2. apache can
be e s t a b l i s h e d .
-
The emphasis on n a t i v e t r o u t f i s h e r i e s
v e r s u s h a t c h e r y trout f i s h e r i e s i s one of
q u a l i t y v e r s u s q u a n t i t y ; t h e g r e a t e r value
l i e s w i t h t r o u t i n t h e water r a t h e r than trout
i n t h e c r e e l . The economic r a t i o n a l e is that
w i t h proper p u b l i c i t y and p u b l i c i n t e r e s t ,
t h e t o u r i s t fisherman w i l l be w i l l i n g t o pay
more f o r t h e o p p o r t u n i t y t o f i s h f o r a r a r e
and b e a u t i f u l n a t i v e t r o u t than t o f i s h for
t h e common h a t c h e r y rainbow t r o u t .
Before %. apache can be widely used to
c r e a t e new f i s h e r i e s i n r e s e r v a t i o n l a k e s ,
d a t a must be gathered from Christmas Tree
Lake on a g e , growth, v u l n e r a b i l i t y t o exploitat i o n and p o p u l a t i o n s t r u c t u r e under exploitat i o n t o provide i n f o r m a t i o n on optimum stocki n g r a t e s and t o d e s i g n s p e c i a l r e g u l a t i o n s
on s i z e and bag l i m i t s t o m a i n t a i n maximum
recreational values.
The watersheds of streams on t h e Apache
R e s e r v a t i o n and elsewhere w i t h populations of
5. a ~ a c h eshould be g r a n t e d s p e c i a l
from p o s s i b l e f u t u r e d e s p o i l a t i o n , comparable
t o w i l d e r n e s s a r e a s of n a t i o n a l f o r e s t s .
Off t h e r e s e r v a t i o n , t h e r e i n t r o d u c t i o n
s apache i n t o b a r r e n streams and g e c r e a of ;
tional l a k e s should be stepped up. This
i s , i n p a r t , dependent on t h e
of h a t c h e r y propagation.
paddy Creek, t h e o n l y known l o c a l i t y i n
the L i t t l e Colorado River b a s i n w i t h a n a t i v e
p o p ~ l a t i o nof S. apache, should be monitored
to determine t h e impact of brook t r o u t on
S. apache. The 1967 survey of Paddy Creek by
Anderson and Behnke noted t h a t t h e headwaters
above a b a r r i e r f a l l s were b a r r e n of a l l f i s h .
~f 5. apache s t i l l e x i s t s i n Paddy Creek, a
above t h e b a r r i e r should b e made
as soon a s p o s s i b l e .
Specimens from p r e v i o u s l y unsampled
l o c a l i t i e s should be e v a l u a t e d f o r r e l a t i v e
p u r i t y i n an a t t e m p t t o d i s c o v e r new populations of 5. apache.
AUTHORITIES
1. Arizona Trout Recovery Team
Joseph L. S t o n e , Leader
Arizona Department of Game and F i s h
Box 387
Pinetop, AZ 85935
Members :
William S i l v e y
Arizona Department o f Game and F i s h
REFERENCES
Behnke, R. J.
1967. G i l a and Apache t r o u t s . Rare and
endangered s p e c i e s r e p o r t . Colorado
Cooperative F i s h e r y U n i t , Colorado S t a t e
U n i v e r s i t y , F t . C o l l i n s . 11 p. (mimeo)
1970. New i n f o r m a t i o n on Gila t r o u t , Salmo
g i l a e . Rare and endangered s p e c i e s r e p o r t .
Colorado Cooperative F i s h e r y U n i t , Colorado S t a t e u n i v e r s i t y , Ft. C o l l i n s . 1 2 p.
(mimeo)
Cope, E. D. and H. C. Yarrow.
1875. Report upon t h e c o l l e c t i o n s of f i s h e s
made i n p o r t i o n s of Nevada, Utah, C a l i f o r n i a , Colorado, New Mexico and Arizona,
d u r i n g t h e y e a r s 1871, 1872, 1873 and 1874.
Rept. Geog. and Geol. Expl. and Survey
West of t h e 100th Merid. (Wheeler Survey)
5:635-703.
.
J o r d a n , D. S and B. W. Evermann.
1896. The f i s h e s of North and Middle America,
p a r t 1. B u l l . U. S. N a t . Mus. 47:1240 p.
M i l l e r , R. R.
1950. Notes on t h e c u t t h r o a t and rainbow
t r o u t w i t h t h e d e s c r i p t i o n of a new
s p e c i e s from t h e G i l a River, New Mexico.
Occ. Pap. Mus. Zool. Univ. Mich. (529).
42 p.
John Adams
U. S. F o r e s t S e r v i c e
Ronald Gumtow
U. S . Fish and W i l d l i f e S e r v i c e
2.
1972. C l a s s i f i c a t i o n of t h e n a t i v e t r o u t s
of Arizona w i t h t h e d e s c r i p t i o n of a
new s p e c i e s , Salmo apache. Copeia 3:401422.
Robert Behnke
Department of F i s h e r y and W i l d l i f e Biology
Colorado S t a t e U n i v e r s i t y
Fort C o l l i n s , CO 80521
(taxonomic i n v e s t i g a t i o n s )
3.
Ronald Gumtow
U. S. Fish and W i l d l i f e S e r v i c e
Box 39
Pinetop, AZ 85935
( f i s h e r y management a d v i s o r t o t h e F t .
Apache I n d i a n Reservation)
4.
Robert R. M i l l e r
Museum of Zoology
University of Michigan
h n Arbor, M I
(taxonomy of
2. apache)
Agriculture-CSU,
Fort Colllns