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a-
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TR EL-82-4
Biological Report 82(11.86)
January 1989
Species Profiles: Life Histories and
Environmental Requirements of Coastal Fishes
and Invertebrates (Pacific Northwest)
SEA-RUN CUTTHROAT TROUT
Fish and Wildlife Service
-US.
Department of the Interior
Coastal Ecology Group
Waternays Experiment Station
US. Army Corps of Engineers
B i o l o g i c a l Report 82(ll. 86)
TR EL-82-4
January 1989
Species P r o f i l e s : L i f e H i s t o r i e s and Environmental Requirements
o f Coastal Fishes and I n v e r t e b r a t e s ( P a c i f i c Northwest)
SEA-RUN CUTTHROAT TROUT
G i l b e r t B. Pauley, Kevin Oshima, Karen L. Bowers, and G. L - Thomas
Washington Cooperative F i s h e r y Research U n i t
School o f F i s h e r i e s
U n i v e r s i t y o f Washington
S e a t t l e , WA 98195
Project O f f i c e r
David Moran
U.S. F i s h and W i l d l i f e S e r v i c e
N a t i o n a l Wetlands Research Center
1010 Gause Boulevard
S l i d e l l , LA 70458
This study was conducted
i n cooperation w i t h
Coastal Ecology Group
Waterways Experiment S t a t i o n
U. S. Army Corps o f Engineers
Vicksburg, MS 39180
Performed f o r
U.S.
Department of the I n t e r i o r
F i s h and W i l d l i f e S e r v i c e
Research and Development
N a t i o n a l Wetlands Research Center
Was h i ngton , DC 20240
T h i s series may be referenced as follows
F i s h and Wildlife Service. 1983-19 . Species profiles: life histories
and environmental requirements of coastal fishes and invertebrates. U. S. Fish
W i l d l . Serv. Biol. Rep. 82(11).
U.S. Army Corps of Engineers TR EL-82-4.
U.S.
This profile may be cited as follows:
Pauley, G. 0. , K. Oshima, K. C. Bowers, and G. L. Thomas. 1989, Species prof'i l e s :
1 i fe hi stories and environmental requirements of coastal fishes and
invertebrates ( P a c i f i c Northwest)--sea-run cutthroat trout. U.S. Fish Wi ld.
Serv. Biol. Rep. 82(11.86).
U.S. Army Corps o f Engineers TR EL-82-4. 21 PP -
PREFACE
This species profile i s one of a series on coastal aquatic organisms,
principally f i s h , o f sport, commercial, or ecological importance. The profiles
are designed to provide coastal managers, engineers, and biologists with a brief
comprehensive sketch of the biological characteristics and environmental
requirements of the species and to describe how populations of the species may be
expected to react to environmental changes caused by coastal development. Each
profile has sections on taxonomy, life history, ecological role, environmental
requirements, and economic importance, i f applicable. A three-ring binder is
used for this series so that new profiles can be added as they are prepared.
This project is jointly planned and financed by the U. S. Army Corps of Engineers
and the U.S. Fish and Wildlife Service.
Suggestions or questions regarding this report should be directed to one of
the following addresses.
Information Transfer Specialist
National Wetlands Research Center
U.S. Fish and Wildlife Service
NASA-Slidell Computer Complex
1010 Gause Boulevard
Slidell, LA 70458
U. S . Army Engineer Waterways Experiment Statior
Attention: WESER-C
Post Office Box 631
Vicksburg, MS 39180
CONVERSION TABLE
M e t r i c t o U.S. Customary
Tc
-
Mu1 t i p l y
Obtain
m i l l i m e t e r s (mm)
c e n t i m e t e r s (cm)
meters (m)
meters (m)
k i lometers (km)
k i lometers (km)
inches
inches
feet
fathoms
statute miles
nautica miles
square meters ( m 2 )
square k i lometers (km2)
h e c t a r e s (ha)
square f e e t
square m i l e s
acres
l i t e r s (1)
c u b i c meters ( m 3 )
c u b i c meters (m3)
ga 1 1 ons
cubic f e e t
acre- f e e t
m i l l i g r a m s (mg)
grams ( g )
kilograms (kg)
m e t r i c tons ( t )
m e t r i c tons ( t )
ounces
ounces
pounds
pounds
s h o r t tons
kilocalories (kcal)
C e l s i u s degrees ("C)
B r i t i s h thermal u n i t s
F a h r e n h e i t degrees
U. S. Customary t o
Metric
inches
inches
feet ( f t )
fathoms
statute miles ( m i )
n a u t i c a l m i l e s (nmi)
mi 11 i m e t e r s
centimeters
meters
meters
kilometers
kilometers
square f e e t ( f t ' )
square m i l e s ( m i 2 )
acres
square meters
square k i l o m e t e r s
hectares
gallons (gal)
cubic feet ( f t 3 )
acre- f e e t
1i t e r s
cubic meters
cubic meters
ounces (02)
ounces ( o z )
pounds ( l b )
pounds ( I b )
s h o r t tons ( t o n )
m i 1 1 igrams
B r i t i s h thermal u n l t s ( B t u )
F a h r e n h e ~ tdegrees ( O r )
grams
k i lograms
m e t r i c tons
metric tons
0.2520
0.5556
iv
(OF
kilocalories
C e l s i u s degrees
CONTENTS
Page
PREFACE . . . . .
CONVERSION TABLE .
ACKNOWLEDGMENTS .
. . . . . . . . . . . . . . . . . .;. . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
NOMENCLATURE/TAXONOMY/RANGE
iii
iv
vi
. .
MORPHOLOGY/IDENTIFICATION AIDS .
REASON FOR INCLUSION IN SERIES .
LIFE HISTORY . . . . . . . . . .
Spawning . . . . . . . . .
Eggs and.Fecundity . . . .
Alevins and Fry . . . . . .
Juveniles and Smolting . .
Saltwater L i f e . . . . . .
AGE AND GROWTH CHARACTERISTICS .
ECOLOGICAL ROLE . . . . . . . .
ENVIRONMENTAL REQUIREMENTS . . .
Temperature . . . . . . . .
Substrate and Cover . . . .
Dissolved Oxygen . . . . .
Turbidity . . . . . . . . .
Water Velocity . . . . . .
Water Depth . . . . . . . .
. . . . . .
. . . . . . . . . .
Timber Harvest
THE FISHERY
LITERATURE CITED .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
ACKNOWLEDGMENTS
The authors thank James Johnston of the Washington Department o f Game and Howard
Fuss of t h e Washington Department o f Fisheries f o r t h e i r reviews and technical
suggestions.
Figure 1.
Sea-run c u t t h r o a t t r o u t .
SEA-RUN CUTTHROAT TROUT
S c i e n t i f i c name.. .. Salmo c l a r k i c l a r k i
Preferred common name. . . .Sea-run cutthroat t r o u t (Figure 1)
Other common names . . . .Coastal cutt h r o a t t r o u t , red-throated t r o u t ,
sea t r o u t , sea-run c u t t h r o a t , searun c u t , bl ueback t r o u t , autumn
t r o u t , harvest t r o u t , ye1 lowbel ly.
Class . . . . . . . . . . . . . . . . . . . . .Osteichthyes
Order .................... Salmoniformes
Family ...................... Salmon idae
---
+
Geographic range: In coastal streams
from northern Cal i f o r n i a through
Oregon and B r i t i s h Columbia and i n t o
southeastern Alaska (Figures 2 and
3).
Rarely found more than 160 km
inland.
MORPHOLOGY/IDENTIFICATION A I D S
The following information i s taken
from Hart (1973), Scott and Crossman
(1973),
and Wydoski
and Whitney
(1978).
Morphological
differences
between coastal cut. t h r o a t and inland
c u t t h r o a t were outlined by Qadri
(1959) and T r o t t e r (1987).
Morphology:
Fin rays--dorsal
fin
anal 8-12, p e c t o r a l s 13, and
pelvic 9. Adipose, small, fleshy and
s l e n d e r , pelvics abdominal i n position
with a free- tipped f 1 eshy appendage
above i n s e r t i o n . Cycloid s c a l e s , 120180 a t l a t e r a l l i n e ; g i l l rakers 1522, rough and widely spaced on f i r s t
g i l l arch.
Body elongate, s l i g h t l y
compressed.
8-11,
I d e n t i f i c a t i o n aids: Red o r orange
s t r e a k along the inner edge o f lower
jaw in fresh specimens.
Small t e e t h
a t the back of the tongue between the
second g i l l c l e f t s .
Teeth
well
developed on upper and lower jaws.
Maxi l lary usual ly extends beyond the
p o s t e r i o r margin o f the eye in f i s h
longer than 10 cm. Back i s greenishblue tending toward m e t a l l i c blue in
f r e s h sea-run f i s h ; s i d e s s i l v e r y ;
d i s t i n c t black spots on b a c k , head,
CANADA
'.
WASHINGTON
OREGON
F i g u r e 2.
Map showing m a j o r r i v e r s t h a t s u p p o r t sea-run c u t t h r o a t t r o u t i n t h e
P a c i f i c Northwest. I t s h o u l d be n o t e d t h a t many small streams t o o numerous t o
be shown on t h i s map a l s o s u p p o r t sea-run c u t t h r o a t s .
An a c t i v e s p o r t f i s h e r y
2
OREGON
/
MILES
0
0
0
50
100
KILOMETERS
e x i s t s f o r these f i s h i n s a l t w a t e r throughout
as
in t h e rivers.
Puget Sound and Hood Canal as well
ALASKA
,
CANADA
ITEO STATES
Figure 3. Sea-run c u t t h r o a t t r o u t coastal d i s t r i b u t i o n from northern California
t o southeastern Alaska and the general l i m i t s of inland d i s t r i b u t i o n in North
America ( a f t e r Johnston and Mercer 1976).
anal f i n , t a i l , and sides (extending
well below l a t e r a l l i n e ) . S i z e range
o f adults i s 0 . 5 to 2.7 kg.
REASON FOR INCLUSION IN SERIES
Although not quite a s well-known a s
i t s larger cousin the steelhead (Salmo
g a i rdneri ) ,
the sea-run cutthroat
t r o u t i s extensively sought by anglers
through the rivers and small streams
of
Northern
Cal if o r n i a ,
Oregon,
Washington, and B r i t i s h Columbia t h a t
flow into saltwater. The freshwater
s p o r t f i s h e r y takes place in the f a l l ,
an extensive saltwater sport
f i s h e r y exists y e a r round in inland
waters such as Puget Sound. The searun c u t t h r o a t i s highly sought a f t e r
by fly-fishermen.
while
LIFE HISTORY
Spawni ng
Sea-run c u t t h r o a t t r o u t have a variable l i f e h i s t o r y , which will be discussed below.
Like salmon, sexually
mature sea-run c u t t h r o a t t r o u t r e t u r n
t o t h e i r n a t a l streams t o spawn.
Spawning sea-run c u t t h r o a t t r o u t home
precisely t o specific t r i b u t a r i e s ,
w h i l e immature f i s h do n o t always
r e t u r n t o t h e i r home stream t o feed o r
when seeking an overwinter h a b i t a t
(Johnston 1982).
Homing o f n a t i v e
sea-run c u t t h r o a t i s extremely p r e c i s e
(Campton l98O), a1though hatcheryp l a n t e d f i s h may s t r a y as much as 30%.
which makes s u r v i v a l r a t e s impossible
t o determine (Johnston and Mercer
1976).
Gel electrophoretic studies
have shown t h a t c u t t h r o a t p o p u l a t i o n s
are g e n e t i c a l l y d i s c r e t e a t t h e small
stream l e v e l (Campton 1980), a1 though
there i s l i m i t e d hybridization w i t h
hatchery-propagated
steelhead t r o u t
(Campton and U t t e r 1985).
The time o f r e t u r n t o freshwater f o r
spawning i s f a i r l y c o n s i s t e n t among
c u t t h r o a t t r o u t from t h e same stream,
b u t v a r i e s widely by geographical
l o c a t i o n (Johnston and Mercer 1976;
Johnston
1982).
In
Oregon
and
Washington, c u t t h r o a t t r o u t r e - e n t e r
freshwater anytime from J u l y through
1952;
Anderson and
March (Sumner
Narver 1975). Very few o v e r w i n t e r i n
s a l t w a t e r (Johnston 1982).
A spring
r u n has been observed o n l y i n Alaska
(Jones 1972). I n a d d i t i o n , a small
percentage o f the immigrants a r e sexuall y
immature i n d i v i d u a l s
(Jones
1973-76; Johnston 1982; T i p p i n g 1986).
I n most coastal r i v e r s o f Washington
and Oregon, the stocks o f f i s h are
s e x u a l l y mature a t f i r s t r e t u r n t o
freshwater; however, a l a r g e percentage of c u t t h r o a t females i n t h e
Columbia River, Puget Sound, B r i t i s h
Columbia, and Alaska do n o t spawn
during the winter o f t h e i r f i r s t
r e t u r n t o freshwater (Johnston 1982).
Anadromous c u t t h r o a t t r o u t
travel
f a r t h e r upstream toward t h e headwaters
of t h e watershed than e i t h e r steelhead
t r o u t o r coho salmon and r e a r sympatr i c a l l y w i t h r e s i d e n t c u t t h r o a t popul a t i o n s (Johnston 1982; Michael 1983).
Spawning g e n e r a l l y takes p l a c e i n
l a t e w i n t e r and spring, b u t t i m i n g
v a r i e s by geographic l o c a t i o n (Dymond
1932; Cramer 1940; S c o t t and Crossman
1973).
I n Puget Sound and southern
B r i t i s h Columbia, coastal c u t t h r o a t
t r o u t e x h i b i t two d i s t i n c t m i g r a t i o n
(1) f i s h r e t u r n i n g t o l a r g e
times:
r i v e r systems b e g i n e n t e r i n g i n J u l y
and peak i n September-October ( e a r l y
e n t r y f i s h ) and (2) f i s h r e t u r n i n g t o
small streams d r a i n i n g d i r e c t l y t o
s a l t w a t e r begin e n t e r i n g i n November
and peak i n January-February ( l a t e
e n t r y f i s h ) (Johnson 1982; Mercer
1982). This d i f f e r e n c e i s most l i k e l y
due t o food avai 1a b i 1i t y , s a l t w a t e r
t o 1 erance, o r stream flows (Johnston
1982).
Throughout t h e i r range, sear u n c u t t h r o a t t r o u t spawn i n small
t r i b u t a r i e s o f large o r small sti-eams
w i t h a drainage area l e s s than 13 km
and may thereby a v o i d c o m p e t i t i o n f o r
r e a r i n g area w i t h steelhead (sea-run
rainbow t r o u t . Salmo a a i r d n e r i 1 and
coho salmon ' ( ~ n c ~ rnh m i u t c h )
(Cramer 1940;
Sumner 19 2; OeWitt
1954; Glova and Mason 1977; Johnston
1982).
Cutthroat
trout
prefer
with
small -tospawning
habitat
moderate-size gravel (Hunter 1973).
A
Spawning behavior i n c u t t h r o a t t r o u t
i s t y p i c a l o f o t h e r stream-spawning
salmonids such as steelhead and salmon
(Smith 1941; Cope 1957; S c o t t and
Crossman 1973).
The female d i g s a
r e d d i n t h e g r a v e l and deposits her
eggs. Simultaneously, t h e male covers
t h e eggs w i t h m i l t , The female then
b u r i e s t h e eggs under a l a y e r o f
gravel.
A1 though c u t t h r o a t t r o u t a r e
r e p e a t spawners, post-spawni ng mort a l i t i e s are sometimes h i g h due t o
weight l o s s and t h e r i g o r s o f spawning
(Cramer 1940; Sumner 1952; Giger 1972;
S c o t t and Crossman 1973).
The f i s h
t h a t s u r v i v e m i g r a t e downstream i n
e a r l y t o l a t e spring.
K e l t s (spent
a d u l t s ) e n t e r s a l t w a t e r e a r l i e r than
smol t i ng j u v e n i 1es (Giger 1972; Jones
1975). Sumner (1952) s t a t e d t h a t 39%
o f the c u t t h r o a t survived the f i r s t
spawning i n Oregon, 17% t h e second,
and 12% t h e t h i r d .
These d a t a are
r e p r e s e n t a t i v e o f c o n d i t i o n s where a
t a r g e t e d c u t t h r o a t f i s h e r y does n o t
exist. Sportfishing pressure reduces
the survival of spawning adults
following the first migration (Giger
1972).
Eggs and Fecundity
The spherical eggs of cutthroat
trout range in size from 4.3 to 5.1 mm
in diameter. Fecundity depends on the
sire and age of the female.
In
Alaska, fish ranging in sire from 34
to 46 cm produced 486 to 2,286 eggs
1975).
In
per
female
(Jones
Washington, females ranging from 20 to
43 cm produced 226 to 4,420 eggs
(Johnston and Mercer 1976). Average
number of eggs was between 1,100 and
1,700 for females of all sizes pooled
(Scott and Crossman 1973). Mercer
(1982) showed a strong linear correlation between increased length and
increased number of eggs, with an
"r" value of -97. Eggs normally hatch
in 28 to 40 days, but may require 50
days or more (Merriman 1935; Cope
1957; Scott and Crossman 1973).
Hatching
is
temperature-dependent
(Merriman 1935).
Alevins and Fry
~ e w l hatched
~
yolk-sac larvae,
called alevins, remain in the gravel
in the redd for 1 to 2 weeks before
they emerge as fry, The fry are less
than 3 cm long and commonly live in
the
shallow, low-velocity stream
margins (Johnston and Mercer 1976).
However, their distribution is often
governed by the presence of other salmonid species (see Ecological Role
section). The first scales are formed
when the fish are 3.5 cm in fork
( F L)--a
length
normal ly
length
attained during the first summer of
life (Cooper 1970; Giger 1972).
The fry are sensitive to many kinds
of environmental changes.
Logging
(Mori ng and Lantz l974), increased
temperatures (Go1 den l975), loss of
cover (Lowery l965), reductions in
food supply, and s i 1 tation (Bustard
and Narver 1975) can all increase
larval mortality. Johnston and Mercer
(1976) listed a number of natural
sources of mortality, such as interspecific
competition
with
other
salmonids, intraspecific competition,
and crowding induced by low summer
flows, but they indicated that habitat
a1 teration was probably the greatest
threat to cutthroat trout stocks.
Juveni 1 es and Smolti ng
Prior to smolting and entering saltwater, juveniles (parr) may migrate
up- and downstream several times
(Sumner 1953; Moring and Lantz 1975).
This migration can result i n confusion
for someone trying to count or estimate the number of smolting cutthroat
trout migrating downstream and out
into the marine environment. The age
at which smolting first occurs is
extremely variable, being somewhat
size-dependent and occurring between
Age I and Age IV (Moring and Lantz
1975) or even later (Johnston and
Mercer 1976; Jones 1977; Fuss 1978).
A good working average is between Ages
I11 and IV. Fuss (1978, 1982) noted
that most initial migrants are Aged
I11 or IV and outlined several reasons why initial migration occurs at
different ages,
Fish in these age
groups average 20-25 cm FL. In Washington and Oregon, downstream movement
of smolts takes place from March to
June, but peaks in mid-May (Johnston
and Mercer 1976).
A division of migration types seems
to exist between cutthroat trout
entering the protected water of areas
such as Puget Sound and those entering
areas of surf-pounded coast. Cutthroat trout entering protected waters
are, on average, younger and smaller
(Age 11, 16 cm FL) (Michael 1983;
Johnston 1980), while those entering
surf zones are, on average, Age IV and
21 cm (Fuss 1982). Regardless o f age
or habitat, cutthroat trout school
before entering the marine environment
and remain schooled throughout their
saltwater migrations (Gi ger 1972)--a
behavior which probably has s u r v i v a l
value.
Saltwater L i f e
Although t h e r e have been few s t u d i e s
o f c u t t h r o a t t r o u t movements a t sea,
i t appears t h a t t h e y overwinter i n t h e
marine environment and s t a y c l o s e t o
shore.
A1 though c u t t h r o a t remain a t
sea v a r y i n g lengths o f time, they r e t u r n t o freshwater i n the same y e a r i n
which they migrated o u t t o sea (Giger
1972; Anderson and Narver 1975; Jones
1976;
Johnston
and Mercer 1976).
I n Puget Sound, Washington,
the
anadromous c u t t h r o a t t r o u t feed and
m i g r a t e along t h e beaches, m o s t l y i n
water l e s s than 3-m deep (Johnston
1980).
I n general, t h e i r movement
a l o n g t h e c o a s t i s b e l i e v e d t o be c o r r e l a t e d w i t h onshore ocean c u r r e n t s ,
w i t h the f i s h staying close t o the
c o a s t l i n e (Giger 1972; Johnston and
Mercer 1976). Regardless o f age, anadromous c u t t h r o a t t r o u t are b e l i e v e d t o
b e g i n schooling j u s t b e f o r e they e n t e r
i n t o the marine h a b i t a t (Johnston
1980). I n Alaska, c u t t h r o a t t r o u t were
r e l u c t a n t t o cross bodies o f water 3
t o 8 km wide', and p r e f e r r e d t o f o l l o w
t h e shore1 i n e (Jones 1976).
-
Many c u t t h r o a t t r o u t have been
captured w i t h scars from p r e d a t o r
attack while a t
sea,
and
that
p r e d a t i o n i s b e l i e v e d t o represent a
major source o f marine m o r t a l i t y
(Giger 1972).
Estimates from Oregon
s t u d i e s i n d i c a t e 20%-40% s u r v i v a l o f
i n i t i a l migrant f i s h i n the marine
environment (Giger
1972).
Tipping
(1986)
noted
that
survival
was
considerably h i g h e r f o r hatchery sear u n c u t t h r o a t t r o u t t h a t were r e l e a s e d
as smolts >21 cm FL (12.8% r e t u r n s )
t h a n f o r f i s h l e s s than t h a t l e n g t h
(2.3% r e t u r n s ) .
AGE AND GROWTH CHARACTERISTICS
Growth i n c u t t h r o a t t r o u t v a r i e s
according t o the type of freshwater
and
sal twater
envi ronments
they
inhabit.
Johnston and Mercer (1976)
summarized growth o f a d u l t c u t t h r o a t
trout
in
the
Pacific
Northwest
(Oregon, B r i t i s h Columbia, and Alaska)
and s t a t e d t h a t f i s h t h a t l i v e i n the
lower stream grow more r a p i d l y than
f i s h t h a t r e s i d e upstream and t h a t
a1 so
basic
stream
productivity
influences
growth.
N i c k e l son and
Larson (1974) i n d i c a t e d t h a t c o a s t a l
c u t t h r o a t t r o u t n o t o n l y l o s t weight
when f o o d i n streams was scarce, b u t
t h a t t h e y a l s o decreased i n length.
It i s n o t known how f r e q u e n t l y t h i s
occurs.
Giger (1972) c i t e d problems . t h a t
were i n h e r e n t i n d e t e r m i n i n g c u t t h r o a t
t r o u t age and growth due t o v a r i a b l e
1i f e c y c l e s and d i f f e r e n t m i g r a t i o n
strategies.
An unusual p a t t e r n o f
age-length d i s t r i b u t i o n s e x i s t s f o r
i n i t i a l outmigrants because t h e f i s h
which spend more time i n streams p r i o r
t o o u t m i g r a t i o n grow slower.
This
slower growth may be a r e s u l t o f the
greater
competition
for
food
in
streams t h a n occurs i n t h e marine
environment.
The r e s u l t i s t h a t f i s h
the
same
system
entering
from
s a l t w a t e r f o r t h e f i r s t t i m e a t Age I V
are o n l y s l i g h t l y l a r g e r than i n i t i a l
o u t m i g r a n t s of Age 11, and are much
s m a l l e r t h a n Age I V f i s h t h a t have
spent one o r more summers a t sea.
(1978)
i n d i c a t e d t h a t backFuss
c a l c u l a t e d l e n g t h s f o r young f i s h
( l e s s t h a n 2 years o l d ) may be i n
error, but the calculations f o r f i s h 2
y e a r s o l d o r o l d e r a r e probably
a c c u r a t e because of the near l i n e a r
r e l a t i o n s h i p between f i s h l e n g t h and
s c a l e r a d i u s f o r the o l d e r f i s h .
According t o Fuss (l978), Age I+
c u t t h r o a t ranged from 69 t o 121 mm and
Age 11+ c u t t h r o a t from 140 t o 180 mm.
These
figures
may
be m i s l e a d i n g
because of t h e a d d i t i o n a l (+) growth.
I n a subsequent paper, Fuss (1982)
i n d i c a t e d more a c c u r a t e l y t h a t Age I
f i s h were 70-77 mm and Age I1 f i s h
The l a t e r work
were 100-113 mm.
involved
more
data
and
better
techniques.
The growth r a t e i n more
northern streams i s slower than in the
more southern streams (Johnston and
Mercer 1976).
Cutthroat t r o u t can l i v e a maximum
of 10 years (Jones 1976), b u t most
adult f i s h runs are made up of
individuals between 3 and 6 years of
age (Johnston and Mercer 1976; Fuss
1982).
Repeat spawners returning f o r
a fourth o r f i f t h spawning a t t a i n
lengths of 17 to 19 inches (Giger
1972; Johnston and Mercer 1976).
and Northcote
1971;
Northcote 1972).
Schultz
and
Habitat s e l e c t i o n by juveni 1e cutt h r o a t t r o u t appears t o be governed
by the presence of o t h e r salmonid
species. In t h e absence of competing
s p e c i e s , c u t t h r o a t t r o u t have been
found t o p r e f e r pools (Glova and Mason
1976; Johnston and Mercer 1976; Glova
1984).
When sympatric with coho
salmon, social dominance i s asserted
by the coho salmon due t o t h e i r
e a r l i e r emergence and l a r g e r body s i z e
(Glova and Mason 1976; Johnston 1982).
ECOLOGICAL ROLE
The use of
i s o l a t e d headwater
streams
by
cutthroat
trout
for
spawning and the f i r s t years of
rearing serves t o reduce hybridization
interactions with other salmonids,
primarily steelhead t r o u t and coho
salmon, which t y p i c a l l y spawn and r e a r
further downstream from nursing zones
of
young-of-the-year
and
Age
I
cutthroat
trout
(Johnston
1982).
Hybridization between c u t t h r o a t t r o u t
and hatchery rainbow t r o u t does not
occur in the few areas of overlap
(Sumner 1972; Campton 1980; Campton
and Utter 1985). Sympatric and a l l o p a t r i c populations of r e s i d e n t and
anadromous c u t t h r o a t t r o u t may a l s o
l i v e within a watershed (DeWitt 1954;
Royal 1972; Scott and Crossman 1973;
Moring and Lantz 1975; Jones 1979;
Johnston 1982).
Another s e l e c t i v e
advantage for i s o l a t i o n of coastal
cutthroat t r o u t , according t o Johnston
(1982), i s in the outcome of social
interactions with anadromous steelhead
t r o u t and coho salmon.
Competitive
interactions f o r food and space between anadromous c u t t h r o a t t r o u t and
steelhead
trout
or
coho
salmon
juveniles a r e most frequently decided
i n favor of the steelhead t r o u t o r t h e
coho salmon (Glova and Mason 1976,
1977; Johnston 1982; Glova 1984).
Coastal cutthroat t r o u t in B r i t i s h
Columbia also have evolved both a
spatial and feeding segregation where
they cohabit with the predacious Dolly
Varden (Salvelinus malma) (Andrusak
Cutthroat and rainbow t r o u t coexist
i n the same reaches of many streams
(Moring and Youker 1979; Nicholas
1978), and occasionally they hybridize
(Campton and Utter 1985). The upper
reaches of the stream a r e usually
dominated by c u t t h r o a t t r o u t , while
rainbow t r o u t dominate the lower
sections
(Hartman and Gill 1968;
Nicholas
1978).
I
areas where
anadromous rainbow t r o u t (steelhead)
e x i s t , t h i s arrangement does not
always occur because the steelhead
juveniles emigrate a t Age I and Age I1
i n the spring, which leaves available
the pools t h a t the o l d e r c u t t h r o a t
- t r o u t seem t o p r e f e r i n a l l sections
of t h e streams (Johnston and Mercer
1976).
I t has been pointed out t h a t
t h e r e a r e t h r e e d i s t i n c t 1i fe history
types of coastal c u t t h r o a t t r o u t :
only one of these i s anadromous, while
the o t h e r two types spend t h e i r e n t i r e
1ives in freshwater (Thomasson 1978;
Michael 1983; Fuss 1982, 1984).
The r e s u l t of i n t e r a c t i o n with
e i t h e r coho salmon o r rainbow t r o u t
tends t o be the displacement of the
juvenile young-of-the-year
cutthroat
t r o u t from the preferred pools to the
The
cutthroat
trout
riffles.
generally return t o the pools a f t e r
f a l l i n g water temperatures reduce
aggressive
i n t e r a c t i o n with these
other species and the heavier winter
flows threaten displacement from the
r i f f l e s (Bustard and - Narver 1975;
Glova and Mason 1976).
Cutthroat t r o u t are opportunistic
feeders (Behnke and Zarn 1976; Wydoski
and Whitney 1978).
Aquatic i n s e c t s ,
general l y t h e most a v a i l a b l e food i n
streams, a r e t h e dominant i t e m i n most
c u t t h r o a t t r o u t d i e t s (Dimick and Mote
1934;
Lowery
1966;
Allen
1969;
Carlander 1969; B a x t e r and Simon 1970;
S c o t t and Crossman 1973; Hunter 1973;
G r i f f i t h 1975; Glova 1984).
Other
foods, such as zooplankton (McAfee
1966;
Carlander 1969; T r o j n a r and
Behnke
1974 ;
Hickman
1977),
t e r r e s t r i a l i n s e c t s (Lowry 1966; Glova
1984;
Martin
1984),
and
fish
(Carlander 1969; Hunter 1973; M a r t i n
1984)
are
important
1ocal l y
or
seasonally.
Many o f t h e coastal
c u t t h r o a t stocks t i m e t h e i r runs t o
c o i n c i d e w i t h t h e a v a i 1a b i 1it y of
salmon eggs i n t h e streams (Johnston
1982).
Cutthroat
trout
become
more
p i s c i v o r o u s as t h e y increase i n s i z e
( I d y l l 1942; McAfee 1966; Carlander
1969; B a x t e r and Simon 1970; Wydoski
and Whitney 1978).
I n freshwater,
c u t t h r o a t t r o u t p r e y on threespine
s t i c k l e b a c k (Gasterosteus aculeatus),
sockeye salmon (Oncorhynchus nerka),
and
coho
salmon
(Lowery
1966;
Armstrong 1971).
There i s considera b l e s i m i l a r i t y and o v e r l a p i n t h e
d i e t o f young c u t t h r o a t t r o u t and
young coho salmon, b u t d i r e c t c o n f l i c t
may be avoided by h a b i t a t p a r t i t i o n i n g
(Glova 1984).
Wilzbach (1985) i n d i cated t h a t food a v a i l a b i l i t y i s rather
i m p o r t a n t i n d e t e r m i n i n g abundance and
microhabi t a t d i s t r i b u t i o n o f a d u l t
c u t t h r o a t t r o u t w i t h i n a stream.
Freshwater p r e d a t o r s o f c u t t h r o a t
f r y i n c l u d e rainbow t r o u t , brook t r o u t
(Sa'lvelinus f o n t i n a l i s ) , D o l l y Varden,
and
shorthead
sculpins
(Cottus
confusus), as w e l l as a d u l t c u t t h r o a t
t r o u t (Horner and B j o r n n 1976). Other
possible predators are great blue
be 1 t e d
herons
(krdea
herodias j ,
k i n g f i s h e r s (Ceryle a l c y o n ) , and mink
(Mustela v i son) a c c o r d i n g t o Horner
and B j o r n n (1976).
I n t h e marine environment, c u t t h r o a t
t r o u t feed on gammarid amphipods,
sphaeromid
isopods,
callianassid
shrimp, immature c r a b s , and v a r i o u s
fish,
including
chum
salmon
;
(0ncorh;nchus,
gorbu&ha)
and P a c i f i c
sand
lance
(Ammodytes
hexapterus)
..
(Armstrong 1971; Simenstad and K i nney
1978); h e r r i n g and s c u l p i n s a r e a l s o
eaten.
Predators of sea-run c u t t h r o a t t r o u t
i n t h e marine environment i n c l u d e
P a c i f i c hake ( M e r l u c c i u s productus),
spiny dogfish
(Squalus a c a n t h i a s ) ,
harbor seal (Phoca v i t a m a d
a d u l t salmon ( ~ i T 1 9 7 7
ENVIRONMENTAL REQUIREMENTS
Temperature
Unusual stream temperatures can l e a d
t o disease o u t b r e a k s i n m i g r a t i n g
f i s h , a l t e r e d t i m i n g o f m i g r a t i o n , and
accelerated o r
retarded maturation
(Reiser and B j o r n n 1979). Most stocks
o f anadrornous salmonids have evolved
to
take
advantage o f
temperature
p a t t e r n s i n t h e i r home streams, and
s i g n i f i c a n t a b r u p t d e v i a t i o n s from t h e
normal p a t t e r n can a d v e r s e l y a f f e c t
t h e i r survival,
Cutthroat t r o u t are not usually
found i n waters where t h e maximum
temperature c o n s i s t e n t l y exceeds 22
OC,
although
they
tolerate brief
p e r i o d s o f daytime w a t e r temperatures
as h i g h as 26 O C i f c o n s i d e r a b l e
c o o l i n g takes p l a c e a t n i g h t (Behnke
and Zarn 1976).
Be1 1 (1973) r e p o r t e d
p r e f e r r e d temperatures o f 9 t o 12 O C
f o r c u t t h r o a t t r o u t , w i t h spawning
temperatures f o r c u t t h r o a t t r o u t t h a t
range from 6 t o 17 O C (Hunter 1973).
egg i n c u b a t i o n
The
duration o f
v a r i e s and i s dependent upon temperature
(Merriman 1935);
t h e optimum
temperature f o r i n c u b a t i o n i s approxi m a t e l y 10 t o 11 O C (Merriman 1935;
Snyder and Tanner 1960).
Egg s u r v i v a l
'
POPULATION
CONSUMPTION
TOTALSTOCK
BIOMASS
0 WATER
TEMPERATURE
FEB MAR APR MAY JUN JUL AUG SEP OCT NOV
DATE
F i g u r e 4. Sea-run c u t t h r o a t t r o u t p o p u l a t i o n consumption and t o t a l s t o c k biomass
(wet weight) versus temperature i n a 500-m l o n g s e c t i o n o f Bear Creek, Washington
(modi f i e d from M a r t i n 1984).
is a l s o dependent upon
(Smith e t a l . 1983).
temperature
Metabolic r a t e s o f j u v e n i l e c u t t h r o a t t r o u t are h i g h e s t between 11
and 2 1 "C (Owyer and Kramer 1975).
According t o M a r t i n (1984), s t o c k
biomass remained n e a r l y c o n s t a n t i n a
g i v e n s e c t i o n o f a small stream i n t h e
Pacific
Northwest
from
July
to
September, b u t the water temperature
rose and food consumption increased
p a r a l l e l t o t h i s r i s e ( F i g u r e 4).
The
optimal temperature f o r j u v e n i l e s i s
15 O C , and e q u i l i b r i u m and a b i l i t y t o
swim i s l o s t between 28 and 30 C'
(Heath 1963).
I n a s t u d y i n southeast Alaska, outm i g r a t i o n o f c u t t h r o a t t r o u t peaked a t
w a t e r temperatures between 4 t o 6 C'
and i n m i g r a t i o n began a t 10 t o 12 O C
and peaked a t 9 t o 10 O C (Jones 1977).
S u b s t r a t e and Cover
There i s c o n s i d e r a b l e v a r i a t i o n i n
size
(gravel
suitable
substrate
diameter) f o r
c u t t h r o a t t r o u t ; they
have been observed spawning i n g r a v e l
o f 2 t o 5 cm (June 1981), 0.6 t o 10.2
cm (Hunter 1973), and 0.16 l o 0.64 cm
(Hooper 1973). Hanson (1977) found 1to
4-year-old
cutthroat trout
in
streams a s s o c i a t e d w i t h s u b s t r a t e s o f
5 t o 30 cm.
I r v i n g and Bjornn (1984)
found t h a t
survival o f cutthroat
embryos increased as t h e percentage o f
f i n e sediments decreased.
The s i z e o f
a d u l t c u t t h r o a t t r o u t a f f e c t s gravels i z e s e l e c t i o n and t h e t a i l s o f pools
i n small t r i b u t a r y streams a r e u s u a l l y
chosen f o r spawning (Gohnston and
Mercer 1976).
Cover f o r f i s h can be provided by
overhanging
vegetation,
undercut
banks, and submerged o b j e c t s such as
l o g s and rocks, as w e l l as by water
depth and t u r b u l e n c e (Giger 1972;
Bustard and Narver 1975; Reiser and
Bjornn 1979).
Cover p r o t e c t s t h e f i s h
from d i s t u r b a n c e and p r e d a t i o n and
a l s o p r o v i d e s shade.
The biomass o f
c u t t h r o a t t r o u t i n streams increases
w i t h t h e amount o f cover present
(Wesche 1974; Lantz 1976; Nickelson
and R e i s e n b i c h l e r 1977).
O i s s o l ved Oxygen
..
Ooudoroff
and
Shumway
(1970)
r e p o r t e d t h a t salmonids t h a t hatched
a t low dissolved-oxygen l e v e l s tended
t o be weak and s m a l l , t o develop
s l o w l y , and t o show increased abnormal it i e s .
C u t t h r o a t t r o u t general l y
a v o i d water w i t h l e s s t h a n 5 mg/l o f
dissolved
oxygen
in
the
summer
(Tro j n a r
1972;
Sekul ic h
1974).
Doudoroff and Shumway (1970)
a1so
demonstrated t h a t b o t h swimming speed
and growth r a t e s o f salmonids d e c l i n e d
as d i ssol ved-oxygen l e v e l s decreased.
Turbidity
According
to
Reiser
and
Bjornn
(1979), salmonid f i s h e s cease movement
o r m i g r a t i o n i n streams w i t h very h i g h
s i l t loads (>4,000 mg/l).
Because
more r a d i a t i o n i s absorbed by t u r b i d
water than by c l e a r water, a thermal
b a r r i e r t o movement and m i g r a t i o n may
develop (Reiser and B j o r n n 1979).
Bachman (1958) r e p o r t e d t h a t c u t t h r o a t
t r o u t a d u l t s stopped f e e d i n g and moved
t o cover a t t u r b i d i t i e s above 35 ppm.
Suspended sediment l e v e l s exceeding
103 ppm,
combined w i t h d i s s o l v e d
oxygen c o n c e n t r a t i o n s l e s s than 6.9
mg/l and v e l o c i t i e s i n t h e redd o f
less than 55 cm/h, can reduce egg
s u r v i v a l t o below 10% ( B i a n c h i 1963).
F r y emergence from t h e g r a v e l may be
hindered by excessive sand and s i l t
(Reiser
and B j o r n n 1979).
These
conditions
may
also
limit
the
production o f benthic invertebrates
necessary
for
optimum r e a r i n g o f
juvenile
fish
(Reiser
and B j o r n n
1979).
Water V e l o c i t y
F r y i n stream environments p r e f e r
shal lower water and slower v e l o c i t i e s
than o t h e r c u t t h r o a t trout 1if e stages
( M i l l e r 1957; Horner and B j o r n n 1976).
V e l o c i t i e s o f l e s s t h a n 0.30 m/s a r e
p r e f e r r e d and t h e optimum i s l e s s than
0.08 m/s (Horner and B j o r n n 1976).
Juveni l e c u t t h r o a t t r o u t i n streams
a r e most o f t e n found i n v e l o c i t i e s o f
0.25 t o 0.50 m/s (T.E.
Nickelson,
unpubl. data).
Thompson (1972) found
young-of-the-year and l - y e a r - 0 1 d c u t throat t r o u t i n water v e l o c i t i e s o f
0.5 t o 0.6 m/s.
Hanson (1977) found
l - y e a r - o l d f i s h i n v e l o c i t i e s averaging 0.10 m/s.
Hanson (1977) a l s o
found 2-, 3-, and 4 - y e a r - o l d c u t t h r o a t
t r o u t a t mean v e l o c i t i e s o f 0.14,
0.20,
and 0.14 m/s,
respectively.
C u t t h r o a t t r o u t have been found
spawning i n small streams w i t h f l o w
r a t e s as low as 0.01-0.03 m3/s (Dimick
and M a r r y f i e l d 1945;
Wyatt 1959;
Moring and Youker 1979). Spawning may
occur i n s e l e c t e d areas o f l a r g e
streams (Moring and Youker 1979).
C u t t h r o a t t r o u t spawning occurs i n
water v e l o c i t i e s r a n g i n g from 0 . 1 1 t o
0.56 m/s i n Washington (Hunter 1973)
and 0.30 t o 0.90 m/s
i n northern
Cal if o r n i a (Haoper 1973).
Coastal c u t t h r o a t t r o u t p r e f e r t o
spawn i n the headwater t r i b u t a r i e s o f
l a r g e r streams.
Summer water f l o w
r a t e s i n these n a t a l creeks seldom
exceed 0.28 m3/s during low flow and
most average 0.12 m3/s (Johnston
r e a r i n g h a b i t a t (Moring
1974; Moring 1975).
Water Depth
THE FISHERY
C u t t h r o a t t r o u t spawn a t t h e t a i l
ends of pools a t depths a s shallow a s
10-15 cm (June 1981) o r a s deep a s 1 m
(Johnston and Mercer 1976).
Hunter
(1973) found c u t t h r o a t spawning i n
water 6-40 cm deep. June (1981) found
some redds i n r i f f l e a r e a s .
Angling f o r sea-run c u t t h r o a t t r o u t
o c c u r s i n both t h e marine and freshwater
environments
(Hi s a t a
1973;
Johnston and Mercer 1976; Washington
1977; Mercer 1982).
Although only
l i m i t e d d a t a a r e a v a i l a b l e on t o t a l
annual h a r v e s t and f i s h i n g p r e s s u r e ,
t h e sea-run c u t t h r o a t t r o u t f i s h e r y
r e p r e s e n t s an important component of
t h e s p o r t f i s h e r i e s of the Pacific
Northwest.
1982 ) .
In streams, a d u l t c u t t h r o a t t r o u t
a r e found i n t h e deeper pools and
slower v e l o c i t y w a t e r , while t h e f r y
a r e found i n shallower, f a s t e r a r e a s
(Gri f f i t h 1972; June 1981).
Timber Harvest
Logging p r a c t i c e s can d i r e c t l y and
indirectly
change
the
physical
environments in t h e small headwater
streams
that
are
the
important
spawning and r e a r i n g a r e a s f o r c o a s t a l
cutthroat trout.
Such changes can
s i g n i f i c a n t l y a1 t e r c u t t h r o a t t r o u t
populations (Hall and Lantz 1969;
Moring 1975; Lantz 1976). Poor logging
p r a c t i c e s i n t h e v i c i n i t y of small
streams can cause a v a r i e t y of changes
t h a t a r e detrimental t o t h e c u t t h r o a t
trout.
These include (1) an i n c r e a s e
i n both t h e maximum and t h e d i u r n a l
f 1u c t u a t i o n o f t h e water temperature
(Hal 1 and Lantz 1969; Moring 1975;
R i n g l e r and Hall 1975; Chamberlin
1982); (2) decreases i n d i s s o l v e d
oxygen i n both s u r f a c e and i n t r a g r a v e l
w a t e r (Hall and Lantz 1969; Moring
1975;
Ringler
and
Hall
1975;
Chamberl i n 1982); ( 3 ) increased s e d i ments i n t h e stream ana cnanges i n t h e
amount of f i n e s p r e s e n t i n t h e gravel
(Hall and Lantz 1969; Moring 1975;
Chamberlin 1982); (4) increased stream
flow r e s u l t i n g i n v e l o c i t y and depth
changes
(Moring
1975;
Chamberl i n
1982); ( 5 ) a l t e r a t i o n of t h e amount of
woody d e b r i s in t h e stream causing pH
changes (Chamberlin 1982); and ( 6 )
1 o s s of
terrestrial
and a q u a t i c
v e g e t a t i o n used a s food sources and
and
Lantz
Angler s u r v e y s conducted by t h e U. S .
National Marine F i s h e r i e s Service i n
1974 i n t h e marine a r e a of Puget
Sound,
Washington,
indicated t h a t
c u t t h r o a t t r o u t were second only t o
salmon i n p o p u l a r i t y among s a l t w a t e r
a n g l e r s (Johnston and Mercer 1 9 7 6 ) .
An e a r l i e r Washington Department of
Game survey i n 1964 showed a t o t a l of
43,700 a n g l e r s f i s h e d f o r anadromous
cutthroat
in
marine
areas
of
Washington S t a t e (Johnston and Mercer
1976).
The
average
per
capita
e x p e n d i t u r e was $25 p e r day i n 1974,
with t h e t o t a l value t o the S t a t e ' s
economy e s t i m a t e d a t $8,850,000 per
year.
Although t h i s d a t a may have
been b i a s e d , t h e r e i s no reason t o
b e l i e v e a d e c l i n e i n p a r t i c i p a t i o n has
o c c u r r e d i n t h e marine f i s h e r y . The
t o t a l p a r t i c i p a t i o n i n and value of
t h e f r e s h w a t e r f i s h e r y f o r anadromous
c u t t h r o a t i n Washington has never been
evaluated.
However,
over
1,800
man-days
were
expended
in
1970
pursuing c u t t h r o a t t r o u t in saltwater
on s o u t h e r n Hood Canal (Johnston and
Mercer 1976).
I n Oregon i n 1972, a n g l e r s caught an
e s t i m a t e d L26,000 a d u l t c u t t h r o a t , 86%
from c o a s t a l streams and 14% from the
Columbia River and i t s t r i b u t a r i e s
(Johnston and Mercer 1976).
They
e s t i m a t e d t h e annual value of t h e
stream c u t t h r o a t t r o u t f i s h e r y t o
Oregon's economy was $3,750,000, based
on an average p e r c a p i t a e x p e n d i t u r e
estimated a t $30 p e r day i n Washington
S t a t e by O l i v e r e t a l . (1975).
The
p r o j e c t e d c a t c h i n Washington and i t s
impact on t h e S t a t e ' s economy has been
assumed t o be g r e a t e r t h a n i n Oregon
due t o grea'ter numbers o f streams i n
Washington S t a t e t h a t c o n t a i n c u t t h r o a t t r o u t and a
l a r g e r human
p o p u l a t i o n c l o s e t o these streams
(Johnston and Mercer 1976).
Tipping (1981) i n d i c a t e d t h a t 84%
o f a l l sea-run c u t t h r o a t t r o u t were
caught by anglers t a r g e t i n g on them,
w h i l e 16% were caught i n c i d e n t a l t o
salmon and steelhead.
Most a n g l i n g
e f f o r t was by p l u n k e r s , w i t h b o a t e r s
second,
and d r i f t fishermen t h i r d
(Tipping and S p r i n g e r 1980; T i p p i n g
1981).
Overall
cutthroat
trout
a n g l i n g e f f o r t i s h i g h e s t i n August
( T i p p i n g and S p r i n g e r 1980), b u t t h e
h i g h e s t catch was i n t h e f i r s t 2 weeks
of September ( T i p p i n g 1981).
Most
anglers caught one f i s h . o r l e s s p e r
trip
(Tipping
and S p r i n g e r 1980;
T i p p i n g 1981).
The m a j o r i t y o f f i s h
caught were s e x u a l l y mature ( T i p p i n g
1981).
The amount of a n g l e r p a r t i c i p a t i o n
1 i k e l y double between 1972 and
1990 i n Oregon and a s i m i l a r t r e n d may
occur i n Washington (Johnston and
will
The v a l u e o f t h e
Mercer 1976).
c u t t h r o a t f i s h e r y t o b o t h Oregon and
Washington economies i s expected t o
i n c r e a s e along w i t h f i s h i n g pressure;
however, i t i s a n t i c i p a t e d t h a t t h e
n a t i v e stocks o f sea-run c u t t h r o a t
w i 11 n o t increase and may d e c l jne due
t o h a b i t a t d e g r a d a t i o n and p o s s i b l e
overfishing
(Johnston
and
Mercer
1976). New r e s t r i c t i v e r e g u l a t i o n s ( 2
f i s h p e r day and 1 2 - i n c h minimum
size)
w i t h i n B r i t i s h Columbia and
Washington, which were designed t o
increase
spawner
escapement,
have
s i g n i f i c a n t l y increased t h e abundance
of
older,
larger
fish
in
many
watersheds (J. M. Johnston, unpubl .
data).
Johnston (1980) i n d i c a t e d t h a t
a two-fish l i m i t i n the Stillaguamish
R i v e r would reduce t h e t o t a l h a r v e s t
o f sea-run c u t t h r o a t t r o u t by about
20%. A 1 4 - i n c h minimum s i z e l i m i t on
sea-run
cutthroat
caught
i n a1 1
marine waters and s e l e c t e d f r e s h w a t e r
streams
was
put
in
force
in
Washington S t a t e i n 1987.
Concurrent w i t h h a b i t a t p r o t e c t i o n ,
agencies r e s p o n s i b l e f o r t h e rnanagement o f sea-run c u t t h r o a t p o p u l a t i o n s
have attempted t o spread t h e h a r v e s t a b l e p o r t i o n o f t h e s t o c k s t o more
a n g l e r s b y imposing r e s t r i c t i o n s on
c a t c h and possession, s i z e , season,
and gear.
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Moring, J. R. , and R. L. Lantz. 1974.
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'
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Univer-
5
4. Title and Subtitle
Species P r o f i l e s : L i f e H i s t o r i e s and Environmental Requirements
o f Coastal fishes and I n v e r t e b r a t e s ( P a c i f i c ~ o r t h w e s t ) - - S e a - r u n
cutthroat trout
ncwn
0.t.
January 1989
L
7. AutMttr)
G i l b e r t 0. Paulev. Kevin Oshima, Karen L. Bowers. and Garv L. Thomas
( 10.
9. h r l o r m i y Omanltmtion Heme and Address
Washington Cooperative Fishery Research U n i t
U n i v e r s i t y o f Washington
S e a t t l e , WA 98195
I Z ~ m n r o & a OmmlUtlon Nam*
PmtuWTasklWw* Und N
;
11. Conrmct(C> or CramlGI No.
(Cl
and Addnss
U.S. Department o f t h e I n t e r i o r
F i s h and W i l d l i f e Service
Research and Development
N a t i o n a l Wetlands Research Center
Washington, DC 20240
U.S. Army Corps o f Engineers
Watarways Experiment S t a t i o n
P.O. Box 6 3 1
Vicksburg, MS 39180
I
15. Supplmumary Notn
*U.S.
Army Corps o f Engineers Report No. TR EL-82-4
Species p r o f i l e s are 1 i t e r a t u r e summaries o f t h e taxonomy, morphology, range, 1i f e
h i s t o r y , and environmental requirements o f c o a s t a l a q u a t i c species.
They a r e designed t o
a s s i s t w i t h environmental impact assessments.
The sea-run c u t t h r o a t t r o u t (Salmo c l a r k i
c l a r k i ) i s anadromous and i s found i n most c o a s t a l streams from Southeast Alaska t o
A t h r i v i n g s p o r t f i s h e r y e x i s t s b o t h i n these freshwater streams
Northern C a l i f o r n i a .
and i n p r o t e c t e d marine waters. Many o f t h e small 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 can
be adversely a l t e r e d by poor timber operations. Optimum temperature f o r i n c u b a t i n g i s 10
t o II O C and eggs hatch i n 28-40 days.
Optimum temperature f o r j u v e n i l e s i s 15 O C and
a b i l i t y t o swim i s l o s t a t about 28 OC.
A d u l t s p r e f e r f a i r l y slow-moving water w i t h
p l e n t y o f cover.
Spawning occurs i n smal 1 diameter g r a v e l .
L i k e s t e e l head t r o u t , they
may r e t u r n from s a l t w a t e r t o spawn several times.
Temperature
Estuaries
Animal migrations
0. Identlhm/+n.End~a
Feeding h a b i t s
Trout
L i f e cycles
Tqrrn.
Sea-run c u t t h r o a t t r o ut
Coastal c u t t h r o a t t r o u t
Salmo c l a r k i c l a r k i
---
Ecological r o l e
Environmental requirements
Timber h a r v e s t