Biology of the Utah chub in Hebgen Lake, Montana
by Richard J Graham
A THESIS Submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree
of Master of Science in Fish and Wildlife Management at Montana State College
Montana State University
© Copyright by Richard J Graham (1955)
Abstract:
An investigation was made on the biology of the Utah chub, Gila atraria, in Hebgen Lake, Montana,
1953-1954. Results from a preliminary study made in 19b8 on abundance and food habits are also
presented. The chub was probably introduced into the lake by bait fishermen. Random sets (49) of gill
nets in 1948 caught 708 Utah chubs, 147 whitefish, 79 brown trout, 31 rainbow trout, 6 cutthroat trout,
3 grayling and 2 suckers.
Gill nets set specifically for chubs in 1953 and 1954 took 1,030 and b,595 chubs respectively. Chubs
appeared to be concentrated in shallow areas in the spring, widely distributed around the lake in
summer and fall, and concentrated in deeper waters in winter. Stomach analyses were made on 55
rainbow trout, 70 brown trout and 165 chubs collected during the summer of 19U8. By volume the
foods of chubs were 48.2 percent algae, 21.1 percent higher aquatic plants and 24.3 percent
microcrustaceans. Analysis of 209 chub stomachs in 1953-1954 showed that insects comprised 36
percent of the total volume, microcrustaceans 36 percent, higher aquatic plants 19 percent, and debris 9
percent. Diptera larvae and pupae constituted about 75 percent of the volume of insects. The peak of
the spawning season for 1953 and 1954 occurred during late June and early July. A rise in the percent
of spent females captured was associated with a rise in air and water temperatures. Most spawning
occurred in water temperatures above 54° F.
Eggs were found on various kinds of bottoms but most were recovered from sand and gravel. The
average number of eggs per female was 40,750. Fry occurred along most of the shallow protected
shorelines. A sample of fry captured on July 7, 195b averaged 0.3 inch in total length. Young taken
October 31, 1953 averaged 1.3 inches. No mature males less than 3 years old or mature females less
than b were aged. The calculated total lengths for each year of life based on b75 specimens were as
follows: first-1.6 inches; second-3.5; third-6.1; fourth-8.2; fifth-9.7; sixth-10.9; seventh-12.b;
eighth-13.6. <
BIOLOGY OF THE UTAH CHUB IN HEBGEN LAKE, MONTANA
RICHARD J . GRAHAM
A THESIS
S u b m itted t o th e G raduate F a c u lty
in
p a r t i a l f u l f i l l m e n t o f th e re q u ire m e n ts
f o r th e d eg ree o f
M aster o f S cien ce i n F is h and W ild lif e Management
at
Montana S ta te C o lleg e
Approved:
HeacD^Major De#a#bmenf
Ch^fcfmari, Examining Committe e
Bozeman, Montana
May, 1 9 &
r‘ Ji / •
-
2-
TABLE OF CONTENTS
Page
A b s tra c t ............................... ...............
3
I n tr o d u c tio n ......................................
h
D e s c rip tio n o f Hebgen Lake
5
F is h a s s o c ia te s .................. .
7
Sam pling a re a s ......................
7
Abundance and d i s t r i b u t i o n . . . .
8
Food h a b its ........................................
10
Spawning ...............................................
15
Season ........................................
15
Areas ..........................................
20
Number o f eggs ......................
22
Age and grow th .................................
23
F ry and f i n g e r l i n g s ...........
23
S iz e and age a t m a tu r ity .
25
Growth ........................................
28
Acknowledgments ...............................
30
Summary .................................................
30
L i t e r a t u r e c i t e d .............................
32
H
'A r?
-
3-
ABSTRACT
An i n v e s t i g a t i o n was made on th e b io lo g y o f th e U tah chub, G ila
a t r a r i a , i n Hebgen L ake, M ontana, 195>3-19$U. R e s u lts from a p re lim in a ry
s tu d y made in 19^8 on abundance and food h a b its are a ls o p re s e n te d . The
chub was p ro b a b ly in tro d u c e d i n t o th e la k e by b a i t fis h e rm e n . Random s e ts
(h9) o f g i l l n e ts in 19U8 c au g h t ?08 Utah ch u b s, lU? w h ite f is h , 79 brown
t r o u t , 31 rainbow t r o u t , 6 c u t t h r o a t t r o u t , 3 g ra y lin g and 2 s u c k e r s .
G i l l n e ts s e t s p e c i f i c a l l y f o r chubs i n 19^3 and 19f?U to o k 1,030 and 1^,595
chubs r e s p e c t i v e l y . Chubs ap p eared to be c o n c e n tra te d i n sh allo w a re a s in
th e s p r in g , w id e ly d i s t r i b u t e d around th e la k e in summer and f a l l , and con­
c e n tr a te d i n d e e p e r w a ters in w in te r . Stomach a n a ly s e s were made on 95
rainbow t r o u t , 70 brown t r o u t and 165 chubs c o lle c te d d u rin g th e summer o f
19li8. By volume th e foods o f chubs were 1^8.2 p e rc e n t a lg a e , 2 1 .1 p e rc e n t
h ig h e r a q u a tic p la n ts and 2 b .3 p e rc e n t m ic ro c ru s ta c e a n s . A n a ly sis o f 209
chub stom achs i n 195>3-195b showed t h a t in s e c t s com prised 36 p e rc e n t o f th e
t o t a l volum e, m ic ro c ru s ta c e a n s 36 p e r c e n t, h ig h e r a q u a tic p la n ts 19 p e rc e n t,
and d e b r is 9 p e r c e n t. D ip te ra la rv a e and pupae c o n s ti tu te d about 75 p e r­
c e n t o f th e volume o f i n s e c t s . The peak o f th e spawning seaso n f o r 1953
and 195b o c c u rre d d u rin g l a t e June and e a r l y J u ly . A r i s e in th e p e rc e n t
o f s p e n t fem ales c a p tu re d was a s s o c ia te d w ith a r i s e in a i r and w ater
te m p e ra tu re s . Most spawning o c c u rre d i n w a te r te m p e ra tu re s above 5b° F.
Eggs were found on v a rio u s k in d s o f bottom s b u t most were re c o v e re d from
sand and g r a v e l. The average number o f eggs p e r fem ale was b 0 ,7 5 0 . F ry
o c c u rre d along most o f th e sh allo w p r o te c te d s h o r e lin e s . A sample o f f r y
c a p tu re d on J u ly 7 , 195b av erag ed 0 .3 in c h i n t o t a l le n g th . Young ta k en
O ctober 3 1, 1953 averaged 1 .3 in c h e s . No m ature m ales l e s s th a n 3 y e a rs
o ld o r m ature fem ales l e s s th a n b were a g ed . The c a lc u la te d t o t a l le n g th s
f o r each y e ar o f l i f e b ased on b75 specim ens were as fo llo w s : f i r s t - 1 . 6
in c h e s ; s e c o n d -3 .5 ; t h i r d - 6 .1 ; f o u r th - 8 .2 ; f i f t h - 9 . 7 ; s ix th - 1 0 .9 ; s e v e n th 1 2 .b; e ig h th - 1 3 .6 .
-ItHTRODUC TION
The U tah chub, G ila a t r a r i a ( G ir a r d ) , i s n a tiv e t o th e B o n n ev ille
B asin o f U tah and th e u p p e r Snake R iv e r d ra in a g e o f loom ing and Idaho
(Simon, 19lt6)..
I t i s presumed t h a t t h i s s p e c ie s was a c c id e n ta l ly in tr o ?
duced in to Hebgen l a k e , Montana by l i v e - b a i t fish e rm e n .
L o c a l r e s id e n ts
r e p o r t t h a t sc h o o ls o f minnows, b e lie v e d to be Utah chub, were f i r s t ob­
s e rv e d d u rin g th e m i d - t h i r t i e s (193£-1937)'»
The chub In c re a s e d r a p id ly
and p ro b a b ly re a c h e d i t s maximum abundance a b o u t 19^8.
I t has rem ained
a t a r e l a t i v e l y h ig h l e v e l s in c e t h a t tim e .
Ghubs have been c o lle c te d in t r i b u t a r i e s s e v e r a l m ile s above Hebgen
L ak e.
T h e ir known ran g e below th e la k e in c lu d e s a l l o f th e Madison R iv e r
and th e u p p er 8£ m ile s o f th e M isso u ri R iv e r ( to H auser Dam).
a ls o be p r e s e n t i n t r i b u t a r i e s o f th e s e r i v e r s .
They may
B a it fish e rm e n r e c e n t l y
in tr o d u c e d th e chub in to C l i f f Lake which l i e s i n an i s o l a t e d b a s in about
12 m ile s w est o f Hebgen L ake. •
The U tah chub i s n o t a good food f i s h and i s a n u is a n c e t o th e f i s h e r ­
men because i t r e a d i l y ta k e s m ost t r o u t b a i t s .
I t i s so abundant t h a t i t
may be c o n tr ib u tin g to a d e c lin e o f th e t r o u t f i s h e r y b u t th e lim ite d d a ta
se c u re d on Hebgen Lake do n o t n e c e s s a r i l y in d ic a te t h i s .
D av is (19I4O) and
S i g l e r (19£3) r e p o r t t h a t a d e c lin e o f th e t r o u t f i s h e r y i n E ish Lake,
U tah ap p eared t o be a s s o c ia te d w ith an in c r e a s e i n th e abundance o f th e
U tah chub.
In fo rm a tio n on th e b io lo g y o f th e U tah chub seemed im p e ra tiv e in th e
developm ent o f a f i s h e r i e s management program f o r Hebgen Lake.
A p re -
.1
Iim in a r y in v e s t i g a t i o n on abundance and food h a b its was made i n 19i[8 by
R . 2U Hays and C. Cr. B ishop o f th e Montana F is h and Game D epartm ent.
A
more in te n s iv e s tu d y on th e b io lo g y o f th e chub was co nducted d u rin g 1953195L by th e w r i t e r .
The r e s u l t s o f b o th s tu d ie s a re p r e s e n te d .
D e s c rip tio n o f Hebgen Lake
Hebgen Lake i s an a r t i f i c i a l impoundment { F ig . l ) lo c a te d on th e
M adison R iv e r w ith in G a lla t in C ounty, a p p ro x im a te ly I m ile w est o f Yellow­
s to n e N a tio n a l P a rk .
The p r i n c i p a l t r i b u t a r i e s a r e j Madison R iv e r, Soufih
Fork o f Madison R iv e r, G ra y lin g C reek and Duck C reek.
in -Y e llo w sto n e N a tio n a l P a rk .
A ll o f th e s e a r i s e
The dom inant p la n t w ith in th e a re a i s
lo d g e p o le p in e (P in u s c o n to r ta ) - th e im m ediate s h o r e lin e o f Hebgen Lake
s u p p o rts a p p ro x im a te ly .e q u a l amounts o f lo d g e p o le p in e and g ra s s la n d -s a g e ­
b ru s h ty p e s .
Most o f th e la n d around th e la k e l i e s on th e N a tio n a l F o r e s t
and i s u se d p r i n c i p a l l y f o r r e c r e a t i o n .
About 75 summer homes and four,
r e s o r t s a re on la n d s le a s e d from th e N a tio n a l F o r e s t S e rv ic e and s e v e r a l
homes and r e s o r t s a re on p r iv a te la n d s .
The dam w hich impounds Hebgen Lake was com pleted i n 19lU and i s owifqd
and o p e ra te d by th e Montana Power Company.
v a tio n o f 6 . ^ k k f e e t m . s . l .
The s p illw a y l i e s a t an e l e ­
The r e s e r v o i r h as a c a p a c ity o f 3UU,730 acyp
f e e t , a s u rfa c e a re a o f 13,700 a c r e s and a maximum d ep th o f 6 l . 5 f e e t .
The maximum re c o rd e d w a te r te m p e ra tu re a t th e s u rfa c e was 76° F .
Ic e
u s u a ll y forms d u rin g th e l a t t e r p a r t o f O ctober o r e a r l y November and dis->
a p p ea rs i n l a t e A p ril o r e a r l y May.
The m ethyl orange a l k a l i n i t y was 77
p .p .m . and pH was 7 ,2 (November 1 1 , 195W .
K-HEBGEN
DAM
O
ABSENT
©
COMMON
•
ABUNDANT
ON
I
0
I
SCALE
MA D I S ON
tie.
I.
hap o f Hebgen Lake showing th e d i s t r i b u t i o n o f Utah chuh f r y
in 1953-1954.
Hebgen la k e i s u sed t o s to r e w a te r f o r downstream power u n i t s .
Be?
f o r e 1953 th e p o lic y was to s to r e w a ter d u rin g th e s p rin g and summer anqj.
t o r e l e a s e - i t as needed in th e f a l l and w in te r .
S in ce 1953 w ater h as b^en
r e le a s e d s h a r p ly in th e f a l l so t h a t th e minimum le v e l i s u s u a ll y re a c h e d
i n November.
In a norm al y e a r th e la k e l e v e l i s lo w ered ab o u t 17 f e e t and
th e volume red u ced t o 160,000 a c re f e e t .
F is h A s s o c ia te s
' The chub i s th e m ost abundant f i s h i n Hebgen l a k e .
Brown t r o u t
(.Salmo t r u t t a ) and m ountain w h ite f is h ( Prosopium w illia m s o n i ) ran k n e x t
fo llo w e d b y rainbow t r o u t (Salmo g a i r d n e r i i ) .
C u tth ro a t t r o u t (Salmo
c l a r k i i ) , e a s te r n brook t r o u t (S a lv e li n u s f o n t i n a l i s ) , American g ra y lin g '
( Thym allus s i g n i f e r ) , lo n g n o se s u c k e r (C atostom us c ato sto m u s) , longnose
dace (R h in ic h th y s c a t a r a c t a e ) > and Rocky M ountain s c u lp in (C o ttu s b a i r d i )
a re a ls o p r e s e n t in l im it e d num bers.
Sam pling A reas
Most o b s e rv a tio n s and c o lle c tio n s w ere made in th e s h a llo w a re a s o f
th e l a k e , p a r t i c u l a r l y th e G ra y lin g and M adison arm s.
The G ray lin g arm
i s co n n ected t o th e main la k e by a s h o r t c h a n n e l c a ll e d "The Narrows"
(T ig . l ) .
Most o f th e arm has a d ep th o f l e s s th a n l5 f e e t and d u rin g
th e w in te r i t i s a lm o st c o m p le te ly d r a in e d .
The p r i n c i p a l bottom m a te r ia l
i s muck a lth o u g h sand and g ra v e l a re a s a re p re s e n t a lo n g th e s o u th e rn
s h o r e lin e .
The e n t i r e arm s u p p o rte d an e x te n s iv e grow th o f a q u a tic veg e­
t a t i o n i n 1918.
Pondweeds (Potamogeto n g ram in eu s, P. p e c t i n a t u s , P .
-
8-
r i c h a r d s o n i i ) , w a te r la d y s thumb ( Polygonum amphibium) , w a te r crow foot
(Ranunculus a c q u a t a l i s ) , American m i l f o i l (M yriophyllum sp ic a tu m ) , and
s e v e r a l s p e c ie s o f a lg a e were common.
L o c a l r e s id e n ts r e p o r t t h a t
a q u a tic v e g e ta tio n became much re d u c ed d u rin g th e fo llo w in g two y e a rs .
By 195>3 o n ly s c a t t e r e d p a tc h e s were fo u n d , m ain ly along th e so u th e rn
s h o re lin e .
The Madison arm i s ab o u t 5> m ile s lo n g and I m ile w id e .
o n e -h a lf o f th e arm h as a d e p th o f l e s s th a n 15> f e e t .
p r im a r i ly o f sand and g r a v e l.
More th a n
The bottom i s
A ll p la n t s p e c ie s l i s t e d above.w ere p re s e n t
b u t pondweeds were m ost a b u n d a n t.
ABUNDANCE AND DISTRIBUTION
F is h c o l l e c t i o n s , e x ce p t f o r f r y and f i n g e r l i n g s , w ere made w ith
graded g i l l n e ts ( sq u are mesh 3/U - 2 in c h e s ) .
I n I 9I48 g i l l n e ts were
s e t a t random th ro u g h o u t th e la k e from J u ly 13 to Septem ber 21.
The r e l a ­
t i v e abundance o f th e v a rio u s s p e c ie s was e s tim a te d from th e s e c o lle c tip n s
(T a b le . I ) .
The n e t t i n g o p e ra tio n s o f 1953 and 195>1| were s e l e c t i v e f o r
chubs in t h a t th e s e t s were c o n fin e d t o a re a s where t h i s s p e c ie s was knpwn
t o be ab u n d an t.
Over ?5 p e rc e n t o f th e 1953-1951 s e ts w ere made i n th e
Madison and G ra y lin g arms d u rin g June and J u ly and a t d e p th s o f l e s s th a n
10 f e e t .
The c o l l e c t i o n s were n o t com parable betw een any two y e a rs wit]a
r e s p e c t to c a tc h p e r hour o r s p e c ie s c o m p o sitio n .
The U tah chub was th e m ost ab u n d an t s p e c ie s in th e 19U8 c o lle c tio n ^ .
In 1953 and 195U th e p e rc e n ta g e o f chubs was c o n s id e ra b ly g r e a t e r b u t tja is
was u n d o u b te d ly due to th e s e l e c t i v e s e t t i n g o f n e t s .
The c a tc h p e r h o u r
-
T able I .
Y ear
19b81
1953%
195b3
9-
F is h c a p tu re d i n Hebgen Lake b y 1 2 ^ -fo o t g i l l n e ts s e t a t r a n ­
dom in 19^8, s e t s e l e c t i v e l y in 1953-195>h*
S p e c ies
U tah chub
M h ite fis h
.Brown t r o u t
Rainbow
C u tth ro a t
G ra y lin g
Sucker
T o ta l
number
708
lb 7
79
31
P e rc e n t
of to ta l
C atch ' ”
p e r.h o u r
7 .3
7 2 .5
1 5 .1
1 .5
8 .1
3 .2
0 .8
d .3
6
0 .6
-
3
2
0 .3
0 .2
-
U tah chub
1M h ite fis h
Brown t r o u t
Rainbow
1030
26
9 1 .9
2 .b
b .8
0 .9
0 .2
o .b
U tah chub
W h ite fis h
Brown t r o u t
Rainbow
G ray lin g
b595 ■
5b
10
8<>3
0 .1
9 0 .2
b .l
6*b
210
265
25
5 .2
0 .5
o .b
1
0 .3
-
-
-
•*" bS s e t s , a v . tim e p e r s e t 2*0 h r s .
^ I4.8 s e t s , a v . tim e p e r s e t 2 .8 h r s .
^ 90 s e t s , a v . tim e p e r s e t 8 .0 h r s .
f o r chubs was as fo llo w s : 19U8, 7»3J 19^3, 8 .3 ; 195h, 6 .I4..
The l a r g e r
c a tc h p e r h our i n 1953 was p ro b a b ly due to s e le c tiv e g i l l n e t t i n g .
The
average tim e f o r s e t s in 19%h was 3 -h tim e s g r e a te r th a n i n 19I48 o r 1953
and t h i s p ro b a b ly a cc o u n ts f o r th e s m a lle r c a tc h p e r h o u r s in c e n e ts s e t
o v e r - n ig h t f r e q u e n tly became so f u l l o f f i s h t h e i r e f f i c i e n c y was re d u c e d .
The 19b8 g i l l n e t s e t s in d ic a te d t h a t th e g r e a t e s t c o n c e n tra tio n o f
chubs was i n th e G ra y lin g arm.
In 195b, a t o t a l o f UU g i l l n e t s e ts was
made i n th e Madison arm and 39 in th e G ra y lin g arm.
The c a tc h p e r hour
-
10 -
f o r chubs was 6 ,0 and 7 ,3 r e s p e c t i v e l y .
Chubs were- abundant in b o th arms
b u t seemed t o be somewhat more c o n c e n tra te d i n G ra y lin g arm.
No c a r e f u l s tu d y was made on th e s e a s o n a l d i s t r i b u t i o n o f th e U tah
chub i n Hebgen L ake, however some, g e n e ra l tre n d s were d i s c e r n i b l e .
The
a d u lt chubs a p p a r e n tly move from th e d e ep e r p a r t s o f th e la k e to th e
sh allo w a re a s w ith th e d isa p p e a ra n c e o f ic e and th e r i s e i n w a te r l e v e l .
On May
19%h an o v e r-n ig h t s e t n e a r th e Narrows i n G ra y lin g arm caught
o n ly t r o u t and w h ite fis h ..
ic e .
At t h i s tim e m ost o f th e la k e was covered w ith
On May 23, a f t e r ic e had d is a p p e a re d , n e ts p la c e d i n th e same a r e a
to o k many ch u b s.
Chubs were abundant i n s h a llo w a re a s th ro u g h o u t th e
summer b u t th e c a tc h showed a d e c lin e i n e a r l y J u ly , 195U*
At t h i s tim e
m ost o f th e chubs had com pleted spawning and many sm all sc h o o ls o f a d u lts
were o b serv ed moving alo n g th e s h o r e lin e s .
R e s o rt owners n e a r th e d eep er
a re a s o f th e la k e r e p o r t t h a t chubs a re seldom observed u n t i l e a r l y J u ly .
■During mid-summer la r g e sc h o o ls were o b serv ed by th e w r i t e r and re p o r te d ■
b y l o c a l r e s i d e n t s i n w id e ly s c a t t e r e d p a r t s o f th e l a k e .
p r e s e n t i n sh allo w a re a s th ro u g h Septem ber and O cto b er.
Chubs were
On November 11,
1931t ( ic e was b e g in n in g to form) a n e t p la c e d in th e sh a llo w s o f G ray lin g
arm to o k no chubs b u t c o n ta in e d w h ite f is h .
These o b s e rv a tio n s in d ic a te
t h a t chubs a re l a r g e l y c o n c e n tra te d i n d e ep e r s e c tio n s o f th e la k e d u rin g
th e w in te r .
A s im ila r s e a s o n a l d i s t r i b u t i o n was re p o r te d f o r th e chub
(S ip h a te le s b i c o l o r ) i n E agle L ake, C a l if o r n ia ( Kimsey, 1 9 $ k )»
FOOD HABITS
D uring th e I 9I1.8 in v e s t ig a ti o n s stom ach ex am in atio n s were made on
-
11 -
rainbow t r o u t , 70 brown t r o u t and 165 U tah c h u b s.
Specimens were c o lle c te d
by a n g lin g and g i l l n e t t i n g a t i r r e g u l a r i n t e r v a l s d u rin g J u n e , J u ly ,
A ugust and S eptem ber.
Stomachs were removed from th e specim ens and im­
m e d ia te ly p re s e rv e d i n fo r m a lin .
The c o n te n ts from each stom ach was
s o r te d in to taxonom ic groups and t h e i r volumes were m easured b y d is p la c e ­
m ent.
The k in d s , p e rc e n ta g e o f o c cu rren ce and p e rc e n ta g e o f volume o f
fo o d o f each s p e c ie s a re g iv e n in Table I I .
The 55 rainbow t r o u t exam ined ra n g e d i n t o t a l le n g th from 6 .8 t o 1 9 .0
in c h e s ( l b u n d e r 12 i n c h e s ) .
A quatic i n s e c t s made up th e l a r g e s t volume
c o n s t i t u t i n g 39«9 p e r c e n t o f th e t o t a l .
D ip te r a la rv a e and pupae made up
about 6b p e r c e n t o f th e volume o f in s e c ts and C o le o p te ra ab o u t 35 p e r c e n t.
O ther o rd e rs o f in s e c t s found were E phem eroptera, H em iptera,. Homoptera,
T r ic h o p te r a , L e p id o p te ra and Hym enoptera.
C la d o ce ra (m o s tly D aphnia)
ran k ed n e x t i n q u a n tity , com prisin g 28.2 p e r c e n t.
A lgae and h ig h e r a q u a tic
p la n ts c o n s t i t u t e d 2»b and 2 .0 p e rc e n t o f th e volume r e s p e c t i v e l y .
Iis h
made up o n ly 0 .9 p e r c e n t o f th e t o t a l volume and u n i d e n tif ie d m a te r ia l and
d e b ris c o n tr ib u te d 2 6 .2 p e r c e n t.
The 70 brown t r o u t ran g ed in t o t a l le n g th from 7*9 to 2 3 .9 in c h es
(2 u n d e r 12 in c h e s ) .
p e rc e n t o f th e t o t a l .
F is h made up th e l a r g e s t volume c o n s t i t u t i n g 69.2
The k in d s and p e rc e n ta g e s (b y volum e) o f f i s h e a te n
were as f o llo w s ; Utah ch u b s, 62; t r o u t , 29; s c u lp in s , 8; u n id e n t i f i e d , I .
The combined volume o f in s e c t s amounted t o 9 .9 p e rc e n t o f th e t o t a l and
D ip te r a ( la r v a e and pupae) com prised ab o u t 88 p e rc e n t o f t h i s .
c o n s t i t u t e d 8 .0 p e rc e n t o f th e volum e.
C lad o cera
Hone o f th e stom achs examined co n -
T able IX .
P e rc e n tag e fre q u e n c y o f o c c u rre n c e and p e rc e n ta g e o f t o t a l volume o f food ite m s e a te n
by 55 rainbow t r o u t , 70 brown t r o u t and l65_ Utah chubs i n Hebgen Lake, I 9I4.8 »
Food organism :................ ‘ O ccurrence '
Algae .......................................
H igher a q u a tic p la n ts . . .
Nematoda .............................
M ollusca .................................
H i r u d i n e a ...............................
C la d o c e r a ...............................
C o p e p o d a .................... ..
A m phipoda......... .....................
E phem eroptera .................... ..
T ric h o p te ra ...........................
D ip te ra ...................................
C o Ie o p te ra i ...........................
O th er in s e c ts ...................... .
A rachnoidea ...................... ...
F i s h " . . . ' . . . . . . . . . . . . .........
U n id e n tifie d and d e b r i s . .
1 t r . e q u a ls t r a c e .
' Il
6
-
13
-
75
Il
U
13
93
36
20
22
Il
67
Volume- ',O ccurrence'
2 oil
2.0
' Utah chub ' ‘ Volume- ' O ccurrence'
Volume
Brown t r o u t
■ "Rainbow t r o u t ■
-
Ooil
2
31
29
-
—
I
0.5
10
T r.
I
28.2
17
2
60
8.0
-
-
-
58
8
OoIl
0.3
9
19
T r;
25.6
IlloO
17
75
11
0.2
o.5
0.3
8.7
OoIl
T r.
T r.
It.
—
T r .1
-
0 .9
26.2
16
20
61
.
T r.
T r.
69.2
11.8
It
2
18.2
21.1
T r.
0 .9
0.7
2li.3
T r.
T r.
.
0.2
—
60
I
-
0.5
Tr.
-
16
-
0.5
Ill .
3 .6
-
H
T
-
ta in e d a lg a e .
13 -
H igher a q u a tic p la n ts amounted .to o n ly O.I4 p e rc e n t o f th e
t o t a l volume and u n i d e n tif ie d m a te r ia l and d e b r is made up 1 1 .8 percent}.
The range i n t o t a l le n g th o f th e 165 chubs u sed f o r stom ach .a n a ly s is
was 3>«3 - lU®5 in c h e s .
A com parison betw een th e food o f s m a ll ( t o t a l
le n g th l e s s th a n 9 in c h e s ) and la r g e chubs showed i t t o be v e ry s i m i l a r .
Algae (U8.2J0 and h ig h e r a q u a tic p la n ts (21.1% ) c o n s ti tu te d 69*3 p e rc e n t
o f th e t o t a l volume f o r a l l ch u b s.
p e r c e n t.
C la d o ce ra ran k ed n e x t co m p risin g 2lw3
The combined volume o f in s e c t s amounted tp o n ly 0 .7 p e rc e n t o f
th e t o t a l and u n i d e n t i f i e d m a te r ia l and d e b r is made up 3 .6 p e r c e n t.
S ig ­
l e r (e g . c i t .), r e p o r te d t h a t th e p r i n c i p a l fo o d ite m s o f 90 chubs from F ig h
L ake, U tah were D aphnia and Gammarus w ith a lg a e ra n k in g n e x t .
C la d o ce ra was th e o n ly ite m ta k e n i n q u a n tity by b o th t r o u t and chubs
and w h ile no d e f i n i t e c o n c lu s io n s can be drawn re g a rd in g th e food compe­
t i t i o n betw een th e s e sp ec ie s, b ecau se o f th e s m a ll sam ple, th e r e ap p ears to
be no s e r io u s c o n f l i c t .
A t o t a l o f 209 stom achs was exam ined from chubs c o lle c te d d u rin g th e
summers o f 19$3-195U.
g i l l n e ts .
Over 90 p e rc e n t o f th e specim ens was se c u re d by
Stomachs were ta k e n o n ly from f i s h cau g h t i n s e t s o f 2-h o u r
d u ra tio n o r l e s s .
The k in d s , p e rc e n ta g e o f o c cu rren ce and e s tim a te d p e r ­
c en ta g e o f volume o f food o f chubs a re g iv e n in Table I I I .
The volumes o f m ic ro c ru s ta c e a and i n s e c t s were e q u a l, each c o n s ti­
t u t i n g 36 p e rc e n t o f th e t o t a l . ' D aphnia was th e .m o s t im p o rta n t c ru s ta c e a n
D ip te r a la r v a e and pupae made up ab o u t 73 p e rc e n t o f th e volume o f in s e c t s
and E phem eroptera nymphs ab o u t 20 p e r c e n t.
O ther in s e c t s found were
—IltTable I I I .
P e rc e n ta g e fre q u e n c y o f o c cu rren c e and e s tim a te d p e rc e n ta g e o f
t o t a l volume o f fo o d item s e a te n by 209 U tah chubs i n Hebgen
la k e., 1953-1951*.
Food organism
O ccurrence
Algae Y ................"............. ..
H igher a q u a tic p la n ts . . . . . .
N e m ato d a ........................................
M ollusca ........................................
C la d o ce ra ......................................
Amphipoda .....................................
Odoriata ............................. ..
E phem eroptera .............................
Hpmoptera . ............................... ..
T r i c h o p t e r a ............................. ..
D i p t e r a ........... ..............................
G o le o p te ra ....................................■
A rachnoidea . . . . . . . . . . . . . .
U n id e n tif ie d and d e b ris . . . .
7
1*1*
I
3;
55
tr.
tr.
18
2
5
61*
tr.
I
59
Volume
t r .1
19 oO .
tr.
tr.
36.0
tr.
tr.
• 8 .0
1 .0
tr.
27.0
tr.
tr.
9. 0
] - t r , e q u a ls t r a c e
Odonata , Homoptera, T r ic h o p te ra and G o le o p te ra . . H igher acjhatic p la n ts
com prised ab o u t 19 p e rc e n t o f th e t o t a l volum e. ■ U n id e n tifie d m a te r ia l and
d e b r is made up th e re m a in in g 9 p e r c e n t.
A com parison betw een th e foods o f chub ta k e n i n 19l*8 and th o se ta k e n
i n 1953-1951* in d ic a te d a change in d i e t .
A pproxim ately 65 p e rc e n t o f th e
stom achs examined in 191*8 were c o lle c te d i n G ra y lin g arm and i n th e v i ­
c i n i t y o f th e N arrow s.
D uring 1953-1951* a p p ro x im a te ly 70 p e rc e n t o f th e
stom achs were c o l l e c t e d i n th e s e a r e a s .
In 191*8 a lg a e o c c u rre d i n 31 p e r ­
c e n t o f th e stom achs and c o n s ti tu te d ab o u t o n e -h a lf o f th e volume- w h ile i n
1953-1951* a lg a e was found i n 7 p e rc e n t o f th e stomachs and amounted to
o n ly a t r a c e o f th e volum e.
I n s e c ts ( p r i n c i p a l l y D ip te ra la r v a e and pupae)
re p la c e d a lg a e i n volume as th e y in c re a s e d from 0 .7 p e rc e n t i n 191*8 t o 36
-
p e r c e n t i n 19!?3-19%b*
15 -
The change in d i e t p ro b a b ly r e s u l t e d from a re d u c ­
t i o n o f a q u a tic v e g e ta tio n which o c c u rre d in th e s e a re a s betw een th e two
s tu d y p e r io d s .
C o n tra ry t o Jo rd a n and Evermann ( 1896) who c h a r a c te r iz e d th e U tah
chub as "e x tre m e ly d e s tr u c ti v e o f o th e r f i s h e s , e s p e c i a l l y to young t r o u t ”,
no f i s h e s o f any k in d were found i n th e stom achs o f th e 37h chubs s tu d ie d .
SPfflING
Season
A ll U tah chubs c o l l e c t e d i n 1953-195U were opened and th e gonads
■examined t o d eterm in e m a tu r ity and s e x .
Depending upon th e c o n d itio n o f
th e o v a rie s th e m ature fe m a les were c l a s s i f i e d as fo llo w s : ( l ) sp e n t o v a rie s w ith v e ry few o r no eg g s; ( 2 ) p a r t i a l l y s p e n t - o v a rie s c o n ta in in g
a b o u t o n e -h a lf t h e i r egg c a p a c ity ; (3 ) f u l l - o v a rie s f u l l o f e g g s.
Some .
v e ry r ip e fe m a les may have l o s t eggs w h ile s tr u g g lin g i n g i l l n e ts b u t
t h i s p ro b a b ly had l i t t l e e f f e c t on th e fin d in g s s in c e th e s e fem ales would
have spawned w ith in a few d ay s.
A t o t a l o f 30I4. m ature fem ale chubs was c o lle c te d May 30- J u ly 12, 1953.
These were c l a s s i f i e d as to th e c o n d itio n o f t h e i r o v a rie s and grouped i n ­
to p e rio d s (T able I V) .
A ll fem ales c o lle c te d on May 30 were f u l l .
The
s p e n t fem ales in c r e a s e d from ab o u t 33 p e r c e n t (June l5 -2 8 ) to ab o u t 76
p e r c e n t (June 2 9 -J u ly 12) w h ile th e f u l l fem ales d e c re a se d from about 50
p e rc e n t to 6 p e r c e n t d u rin g t h i s p e r io d .
A pproxim ately 20 p e rc e n t o f th e
fe m a les ta k e n were p a r t i a l l y s p e n t.
The 19$b c o l l e c t i o n o f fem ale chubs t o t a l e d 1 ,666 and a l l e x ce p t 27
-16Table IV .
Ovary c o n d itio n o f chubs c a p tu re d d u rin g 1953 i n Hebgen Lake.
Number
of
Fem ales
P e rio d
" 5 /3 0
6 /l5 - 6/21
6/22 - 6/28
6/29 - 7/5
7/6 - 7/12
16
55
3b
59
IbO
o f th e s e were ta k e n b y g i l l n e t s .
F u ll
P e rc e n t
P a rtia lly
S pent
Spent
100
b5.5
50.0
5.0
6.b
23.6
l b .7
17.0
18.6
30.9
35.3
78.0
75.0
The fem ales were c l a s s i f i e d and th e n
grouped i n t o .p e rio d s e x te n d in g from Hay 23 t o A ugust-6 ( F ig . 2 ) .
During,
th e f i r s t c o l l e c t i o n p e rio d (May 23-30) o n ly one p e rc e n t o f th e c a p tu re d .
fem ales was s p e n t.
The s p e n t fem ales ta k e n May 31-Jnne 20 rem ained a t a
low l e v e l (13»5 p e r c e n t) b u t in c re a s e d to a b o u t 63 p e r c e n t f o r p e rio d s
e x te n d in g June 2 1 -J u ly 1 1 .
Over 95 p e rc e n t o f th e fem ales c o lle c te d J u ly
12-A ugust I were s p e n t, and d u rin g th e l a s t p e rio d (A ugust 2 -6 ) a l l were
s p e n t.
The h ig h r a t e o f in c r e a s e in s p e n t fem ales w ith a c o rre sp o n d in g d e­
c re a s e in f u l l fem ales in d ic a te s t h a t th e peaks o f spaw ning fo r—19-53- and
125il, o c c u rre d d u rin g l a t e June and e a r l y - J u l y .
In 195b th e l a r g e s t pe r -
c en ta g e s o f p a r t i a l l y s p e n t fem ales o c c u rre d betw een Jjm e_21 and J u ly 1 1 ,
and t h i s i s f u r t h e r e v id en c e t h a t th e peak o f spawning o c c u rs a t t h a t
The b e g in n in g and ending d a te s o f th e 1953 spawning sea so n were n o t
tim e .
d e te rm in e d .
The 195b sea so n a p p a r e n tly began i n May. and ex te n d e d in to
A ugust.
Numerous r i p e m ales were observ ed th ro u g h o u t th e 1953 c o l l e c t i n g
SAMPLE
SIZE
PERI OD
5/ 2 3 - 5 / 3 0
5/ 3 1 - 6 / 6
6/ 7 - 6/13
6/ 1 4 - 6 / 2 0
6/21-6/2 7
6/28
7/4
-
7/ 5 - 7/ 11
i
i—i
C
7/ 1 2 - 7/18
I
7/19 - 7 / 2 5
7/26
8/2
-
-
8/1
8/6
r
40
50
60
PERCENT
r . 2.
Ovary c o n d itio n s o f 1,666 chubs c a p tu re d d u rin g th e s p rin g o f 1954.
-
p e rio d (May 3 0 -J u ly 1 2 ) .
18 -
In 19$k, r i p e m ales were abundant from th e
e a r l i e s t c o l l e c t i o n s (May 23-30) u n t i l m id -J u ly .
There was some i n d i ­
c a tio n t h a t m ales' r ip e n e d so o n er th a n fe m a le s .
A ir te m p e ra tu re s f o r 195>3-195>h were o b ta in e d from th e U n ite d S ta te s
D epartm ent o f Commerce w e a th e r s t a t i o n a t Hebgen Dam.
Two w a te r te m p e ra -.
t u r e s t a t i o n s were e s t a b l i s h e d i n Hebgen Lake, one in th e Madison arm and
th e o th e r a t th e H arrow s.
Maximum-minimum therm om eters were p la c e d ab o u t
2ir -fee t below th e s u r f a c e and re a d in g s were ta k e n a t i r r e g u l a r i n t e r v a l s
d u rin g c o l l e c t i n g p e r io d s .
The av erag e a i r te m p e ra tu re (ItOoh0 T .) f o r ■
May, 195>3 was ho6° below normal*
The av erag e te m p e ra tu re f o r June (5>2el °
F . ) was norm al and th e J u ly averag e (6 2 .9 ° F .) was 2 ,8 ° above norm al.
The
w a ter te m p e ra tu re d u rin g th e peak o f spawning (June 17- J u l y 9) averaged.
6 0 .2 ° F . w ith a maximum o f 68° and a minimum o f 5>h°.
I n 195h th e average a i r te m p e ra tu re s f o r May (h 6 .9 ° F . ) , June (5)0.1°
F .) and J u ly 6 3 ,0 ° F .) were 1*9° above, 2 ,0 ° below and 2 .9 ° above norm al
r e s p e p tiv e ly .
Average a i r and w a ter te m p e ra tu re s were d e term in e d f o r
p e rio d s c o rre sp o n d in g to chub c o l l e c t i n g p e rio d s and th e n compared w ith
th e in c id e n c e o f s p e n t fem ales (F ig . 3 ) .
began d u rin g th e warm w eath er o f mid-May.
The 195?h spawning seaso n p ro b a b ly
Qn May 26 th e w e ath e r tu rn e d
c o ld and low te m p e ra tu re s p r e v a ile d u n t i l June 20.
The av erag e w a ter
te m p e ra tu re s betw een May 30 and June 21 were below 5>5>° F . and th e oc­
c u rre n c e o f s p e n t fem ales d u rin g t h i s tim e rem ained below 20 p e r c e n t.
The
m arked in c re a s e i n a i r and w a te r te m p e ra tu re f o r th e p e rio d June 21-27 was
a s s o c ia te d w ith an in c r e a s e i n th e p e rc e n t o f s p e n t fe m a le s .
Most spawn-
90
WATER
AI R
TEMPERATURE
T E MP E R A T U R E
SPENT
FEMALES
TEMPERATURE
^
16-22
31-6
Fier. J .
12-18
21-27
2 3 -3 0
MAY
2 8 -4
1 4 -2 0
JUNE
JULY
R e la tio n s h ip between a i r and w ater te m p e ra tu re s , and th e p e rc e n t o f
s p e n t fem ales o c c u rrin g in p e rio d ic c o lle c tio n s i n Heogen Lake, 1954.
-
20 -
in g o ccu rs i n w a te r te m p e ra tu re s above Zb0 F .
A reas
Two methods were u sed to lo c a t e chub spawning a r e a s t Cl) o b serv in g
th e d i s t r i b u t i o n o f f r y w hich would in d ic a te th e lo c a t io n o f spawning
a re a s w ith r e s p e c t t o th e la k e s h o r e lin e ; ( 2 j s e l e c t i n g s p e c i f i c a re a s
f o r bottom sam pling to re c o v e r e g g s.
The d i s t r i b u t i o n o f f r y was o b ta in e d by su rv e y in g th e la k e s h o re lin e
d u rin g 1953-19!?b (F ig . l ) .
by d i r e c t o b s e r v a tio n .
T h e ir p re se n c e was d eterm in ed b y s e in in g and
The le n g th o f s h o r e lin e su rv ey ed a t each sam pling
p o in t v a r ie d from 75> t o 3 ,5 0 0 y a rd s .
The w e ste rn p a r t o f th e main la k e from th e dam t o W atkins Greek i s .
c h a r a c te r iz e d by s te e p bottom s and no f r y were found t h e r e .
The sh o re
from W atkins C reek t o th e South Fork arm has s te e p bottom s in te r s p e r s e d ,
w ith sh a llo w a r e a s .
n e v e r a b u n d an t.
F ry were l o c a l l y d i s t r i b u t e d i n p r o te c te d a re a s b u t ■
A few f r y were p re s e n t i n s e v e r a l sh allo w bays lo c a te d
i n th e South F o rk arm.
F ry were d i s t r i b u t e d in th e numerous s h a llo w a re a s
along th e so u th e rn s h o r e lin e o f th e M adison arm.
s e rv e d i n c e r t a i n o f th e s e a r e a s .
Only one heavy c o n c e n tra tio n o f f r y was
found along th e n o rth e rn sh o re o f th e M adison arm.
t e c t e d shallow a r e a .
Large numbers were ob­
T h is was i n a p ro ­
F ry were abundant in s e v e r a l p r o te c te d sh a llo w a re a s
which o ccu r alo n g th e s h o r e lin e from th e M adison arm to th e N arrow s.
N e a rly a l l o f G ra y lin g arm i s sh allo w and th e p r i n c i p a l b ottom m a te r ia l i s
s i l t and muck a lth o u g h sand and g ra v e l a re a s a re p r e s e n t .
F ry were found
along m ost o f th e so u th e rn s h o re lin e b u t heavy c o n c e n tra tio n s were con­
-
21-
f in e d to a re a s w hich had bottom s composed o f sand and g r a v e l .
seldom found along th e n o rth e rn sh o re s o f t h i s arm.
F ry were
In 191*8, when a q u a tic
v e g e ta tio n was abundant i n G ra y lin g arm , numerous f r y were observed in
c e r t a i n a re a s which had bottom s o f s i l t and muck.
These same a re a s had
few o r no f r y in 19!?3-19!?h when v e g e ta tio n was n e a r ly a b s e n t.
No i n f o r ­
m ation was o b ta in e d on th e in flu e n c e o f v e g e ta tio n on spawning o r on th e
s u r v iv a l o f eggs o r f r y .
Few p r o te c te d sh a llo w a re a s o ccu r betw een G ray­
l i n g arm and th e dam and no f r y w ere found alo n g t h i s s h o r e l i n e .
S o u th w e s te rly w inds p r e v a i l d u rin g th e summer w hich s u b je c t th e
n o r th e r n sh o re s t o s e v e re wave a c tio n .
F ry were seldom found i n exposed
a re a s even th o u g h o th e r f a c t o r s seemed fa v o ra b le f o r spaw ning.
F ry
o c c u rre d along m ost s h a llo w , p r o te c te d s h o r e lin e s and h e a v ie s t concen­
t r a t i o n s o f f r y were found i n th e Madison and G ra y lin g arms*
The s h a llo w
a re a s where f r y were m ost abundant had bottom s composed o f sand and
g r a v e l.
In 195)1*, s p e c i f i c a re a s were s e le c te d f o r bottom sam pling in. an
a tte m p t t o re c o v e r e g g s .
The i n i t i a l e f f o r t was w ith a P e te rs e n d red g e.
\
T h is method was abandoned b ecause n o t enough a re a c o u ld be sam pled i n a .
re a s o n a b le tim e .
Chub eggs were c o lle c te d by rem oving th e t h i n s u rfa c e
la y e r o f th e bottom w ith a f l a t t e n e d c o n ta in e r , o r by d ra g g in g a f i n e mesh i n s e c t n e t th ro u g h bottom m a te r ia l s t i r r e d up by k ic k in g .
Eggs were
re c o v e re d from bottom m a te r ia ls by s u c c e s s iv e w ashings th ro u g h graded
screen s.
No q u a n t i t a t i v e sam ples were tak en *
Eggs were re c o v e re d from 25> o f 1*7 sam ples ta k e n June 2 ^ -J u ly 9«
They
-22
were found on v a rio u s k in d s o f bottom s in c lu d in g g r a v e l, san d , s i l t , muck
and d e t r i t u s , b u t most o f them were re c o v e re d from sand and g r a v e l.
d e p th s a t w hich eggs w ere found v a r ie d from I t o It f e e t .
The
They were un­
d o u b te d ly p r e s e n t a t g r e a te r d e p th s b u t no sam ples were ta k e n because o f
method l i m i t a t i o n s .
The d is ta n c e from sh o re where eggs were found v a r ie d
from 2 to 15>0 f e e t .
Submerged p la n ts w ere n o t abundant d u rin g th e sam pling p e rio d and
th o s e p r e s e n t had a t t a i n e d v e ry l i t t l e grow th.
No eggs w ere found ad­
h e rin g t o p l a n t s .. Numerous o b s e rv a tio n s o f submerged s n a g s , stumps and
b ru sh i n s h a llo w w a te r re v e a le d no eggs..
Two mats (3 b y L f e e t ) o f woven
w illo w b ra n c h e s , a p ie c e o f d riftw o o d , and an ir o n p ip e were p la c e d a t
d ep th s o f 8-10 f e e t i n a re a s where spawning was b e lie v e d to o c c u r.
These
were checked p e r i o d i c a l l y d u rin g th e spawning' p e rio d b u t no eggs were
found a d h e rin g to them .
known spawning a r e a s .
s e rv e d .
None were ta k e n i n s u rfa c e p la n k to n h a u ls over
D e p o sitio n and f e r t i l i z a t i o n o f eggs were n o t ob­
No evidence was fo u n d o f n e s t c o n s tr u c tio n and th e d i s t r i b u t i o n
o f eggs in d ic a te s t h a t th e y a re b ro a d c a s t o v er th e bottom®
U n t i l 1.91x9, th e F is h and Game D epartm ent m a in ta in e d rainbow t r o u t
spawning s t a t i o n s on s e v e r a l t r i b u t a r i e s t o Hebgen L ake.
Traps were o p e r­
a te d d u rin g May and Ju n e , and v e ry few chubs were ta k e n .
No movement o f
chubs i n t o t r i b u t a r y stream s was o b serv ed b y th e w r i t e r .
Number o f Eggs
Approxim ate egg numbers were d e term in e d f o r 7 fem ales (egg s a c s s t i l l
i n t a c t ) c o lle c te d d u rin g Ju n e , 1953 (T able V ).
These specim ens ran g ed i n
-
Table V.
23-
C a lc u la te d numbers o f eggs f o r 7 U tah chubs c o lle c te d i n Hebgen
Lake.
T o ta l'L e n g th ,
in c h e s
W eight, pounds
- 8 .8
1 0 .3
IOoll
1 0 .9
1 1 .7
1 3 .U
1 3 .8
13,900
32,300
2 1 ,3 0 0
U7,3oo
li7,Uoo
38,3oo
6 2 , Uoo
0o3ti
0 .6 l
0 .3 7
0.7U
0 .8 3
-
1 .3 7
t o t a l le n g th from 8 .8 t o 1 3 .8 in c h e s .
c a lc u la te egg num bers.
Number o f eggs
The v o lu m e tric method was u sed to
The average number o f eggs p e r fem ale was UO37^0
w ith a minimum o f 1 ^,900 ( 8 .8 in c h f i s h ) a n d ' a maximum o f 623U00 (1 3 .8
in c h sp ecim en ).
AGE AND GROTdJTH
F ry and F in g e r lin g s
The f i r s t f r y were o b serv ed i n 195>3 on A ugust 3«
ra n g e d from 0»U t o 1 .3 in c h e s w ith an av erag e o f 0 .8 .
T h e ir t o t a l le n g th s
I n 195>U> f r y were
f i r s t o bserved on J u ly 7 and th e s e ra n g e d i n t o t a l le n g th from 0 .2 3 t o 0 .3
in c h e s w ith an av erag e o f 0 .3 .
Newly h a tc h e d f r y were p r e s e n t i n bank
d e p re s s io n s , in w e ll p r o te c te d p o c k e ts c r e a te d by d riftw o o d and s c a tte r e d
th ro u g h em ergent v e g e ta tio n .
They were found w ith in a few in c h e s o f th e
s h o r e lin e i n a re a s where banks o r o th e r c o v er was la c k in g .
As f r y i n ­
c re a s e d i n s iz e th e y were p r e s e n t a t g r e a t e r d is ta n c e s from sh o re 3
p a r t i c u l a r l y i f submerged v e g e ta tio n was p r e s e n t.
F ry and f i n g e r l i n g s were c o lle c te d a t i r r e g u l a r i n t e r v a l s from August
~2ht o O ctober i n 1953 and i n J u ly and Septem ber i n 19$h (T able V I).
F in g e r-
lin g s -which av erag ed 1 .3 in c h e s i n t o t a l le n g th were c o l l e c t e d on O ctober
3 1 , 1953.
Sam pling was lim it e d t o a r e a s w ith d ep th s t h a t could, be waded.
D uring l a t e Septem ber and O ctober f i n g e r l i n g s became s c a rc e i n th e s e
w a te r s .
The average t o t a l le n g th o f young o f th e y e a r d u rin g th e s e
months i s p ro b a b ly g r e a t e r th a n in d ic a te d i n th e sam ples s in c e l a r g e r ■
f i s h a p p a r e n tly move i n t o d eep er w a te r .
. Table V I.
S iz e o f Utah chub f r y and f i n g e r l i n g s in c o ll e c t i o n s from
Hebgen L ake.
P e rio d
Aug. 3 -6 , 1953
Aug. 2 7 -2 8 , 1953
S e p t. 1 5 -1 6 , 1953
O c t. 10, 1953
J u ly 7 -9 , 1954
J u ly 2 1 -2 8 , 1954
S e p t. 7 -8 , 1954
T o ta l le n g th (inches)^Average
Range
Number
0 .4 - 1 .3
0 .6 - 2 .1
0 .6 - 2 .0
0 .8 - 2 .0
0.2$-» 0o5
0 ,2 $ - 0 .7
0 .8 — l* $
275
345
26$
62
224
226
157
0 .8
. 1 .0
1 .2
1 .3
0.3
0 o$
1 .1
^M easurements from specim ens p re s e rv e d i n 10% fo rm a lin
The p re se n c e o f f r y (0 .8 in c h i n t o t a l le n g th ) i n th e c o l l e c t i o n o f
O ctober 3 1, 1953 su g g e s ts t h a t a t l e a s t a few chubs may n o t form s c a le s
d u rin g t h e i r f i r s t y e a r o f l i f e .
S c a le s w ith one to th r e e o i r o u l i were
found on f i s h 1 .0 in c h in t o t a l le n g th .
S c a le s were n o t d e te c te d on f i s h
0»8 in c h lo n g b u t bony p l a t e s w ith o u t c i r c u l i were found on s e v e r a l
specim ens w ith a t o t a l le n g th o f 0 .9 in c h .
Kimsey (o p . c i t .) found
s c a le s form ing i n S ip h a te le s b ic o lo r which had s ta n d a rd le n g th s o f 0 .7 8 0 .9 7 in c h e s .
—25>—
A le n g th fre q u e n c y polygon o f 189 f r y and f in g e r l i n g s c o lle c te d from
.
■
one a re a on August 6 , 19^3 in d ic a te s two. age c la s s e s were p r e s e n t (F ig 6
k )»
The av erag e t o t a l le n g th s o f f i s h i n th e f i r s t and second groups
were 0 .9 and 2 ,8 in c h e s r e s p e c t i v e l y .
A s tu d y o f t h e i r s c a le s showed th e
f i s h i n th e second group t o be y e a r lin g s .
S iz e and Age a t M a tu rity
T o ta l le n g th s were ta k e n on random sam ples o f m ature m ale, m ature
fe m a le , and im m ature chubs c o lle c te d by g i l l n e ttin g i n 193k (F ig . £ )•
A ll f i s h w ith u n d eveloped gonads were c l a s s i f i e d as im m atu re.
n o t se x e d .
These were
The $2h m ales i n t h i s sample ra n g e d in le n g th from £ .8 to
1 1 .8 in c h e s w ith an average o f 9 .It.
The 2&k fem ales v a r ie d i n le n g th
from 7 .It t o l i t »2 in c h e s w ith an average o f 1 0 .6 o r more th a n one in c h
g r e a t e r th a n f o r m a le s.
The le n g th fre q u e n c y o f th e s e f i s h s u g g e s ts an age group b e tw e e n .
5 .0 and 7«5 in c h e s and a n o th e r betw een 7»5 and 9 .0 in c h e s .
S c a le s tu d ie s
show t h a t f i s h i n th e f i r s t s iz e group were n e a r ly a l l 3 y e a rs o ld and
th o se in th e second were It y e a rs o ld .
A t o t a l o f 166 f i s h com prised th e
f i r s t group and 7lt.lt p e r c e n t o f th e s e were im m ature, 2 5 .0 p e rc e n t were
m ature m ales and 0 ,6 p e rc e n t were m ature fe m a le s .
The seco n d group
t o t a l e d 182 f i s h and 2 9 .1 p e rc e n t o f th e s e were im m atures, 5 7 .1 p e rc e n t
were m ature m ales and 1 3 .8 p e rc e n t were m ature fe m a le s.
No m ature m ales
aged by th e s c a le method were l e s s th a n 3 y e a rs o ld and no m ature fem ales
were l e s s th a n It.
o ld .
Most o f th e m ature m ales and fem ales w ere 5 o r 6 y e a rs
A few chubs w ith undeveloped gonads were aged a t 5 y e a rs o ld .
Ct 30
TOTAL
F i f . 4*
LENGTH - INCHES
Length freq u en cy fo r 1^9 chubs c o lle c te d on August b, 1953
from one lo c a tio n in Hebgen Lake.
MAT URE
FEMAL ES
MATURE
MA L E S
I MMATURE
W
7 O-
5.0
6 .0
7 .0
8 .0
TOTAL
F ig . 5.
Length fre q u e n c ie s f o r
9 .0
10.0
L E NGT H
11.0
-
12.0
13.0
14.0
I NCHES
m ature m ale, 2P4 m ature fem ale and 175
immature chubs c o lle c te d by g i l l n e ts in Hebgen Lake, 1954.
15.0
-
28 -
There i s a c o n s id e ra b le o v e rla p betw een immature and m ature chubs w ith
r e s p e c t . t o s iz e and a g e „
M ales a p p a r e n tly m ature a y e a r younger th a n
fe m a le s .
Growth
The age and grow th o f th e U tah chub i n Hebgen Lake were b ased on l75>
specim ens (l8 8 m ature m a le s, 183 m ature fe m a le s , IO l im m atures) c o lle c te d
d u rin g 1953-195U®
These f i s h ran g ed i n t o t a l le n g th from 2*2 to lU»3
in c h e s and r e p r e s e n te d a l l o f th e age g ro u p s , I t o - V H I .
S c a le s were
ta k e n from th e l e f t s id e o f th e body betw een th e l a t e r a l l i n e and d o r s a l
fin .
M n u li beyond th e f i f t h y e a r w ere, i n g e n e r a l, d i f f i c u l t t o d e te c t .
becau se o f t h e i r c lo s e p ro x im ity t o one a n o th e r .
made alo n g th e a n t e r i o - l a t e r a l r a d i u s .
S c a le measurem ents were
U n co rrected c a lc u la te d t o t a l -
le n g th s were d eterm in ed w ith a nomograph, assum ing a l i n e a r r e l a tio n s h ip
betw een s c a le and body grow th.
Because o f obvious d if f e r e n c e s betw een
th e s iz e o f m ales and fem ales th e r e s u l t s were ta b u la te d s e p a r a te ly
.
(T able V IT ).
The average c a lc u la te d le n g th a t each an n u lu s was c o n s is te n tly
g r e a te r f o r fe m a les th a n f o r m a le s.
T his d if f e r e n c e g r a d u a lly in c re a s e d
from 0 .1 in c h i n th e f i r s t y e a r o f l i f e t o 0 .7 in c h i n th e s e v e n th .
Tw enty-seven fem ales and 7 m ales were 7 y e a rs o ld , and U fem ales and no
m ales w ere 8 y e a rs o ld .
This would in d ic a te t h a t fem ales l i v e to be o ld e r
th a n m ales •
The average c a lc u la te d le n g th o f a l l chubs a t th e end p f each y e a r
o f l i f e fo llo w s : f i r s t - 1 . 6 ; se c o n d -3 .3? t h i r d - 6 . 1 ; f o u r t h - 8 , 2; f i f t h - 9 . 7 ;
TcMe VII
/verage c a lc u la te d t o t a l le n g th s (in ch es) o f Utah chubs c o lle c t e d in 1#3-193L fr o r Uebgen Lake.
F - mature fem ales)
Average t o t a l
le n g th (in c h e s)
a t capture
T1Unber
Year o f L ife
?:
F
I
I
38
2 .8
II
2
li.S
III
38
15
f .2
r;
2L
22
7
7 .6
7
2
56
Ui
8 .2
VI
V II
F
I
M
F
I
K
F
I
?:
6.2
6 .2
F
I
I!
6
5
F
I
8.2
::
F
I . Ii
1 .6
6 .2
3 . Ii
3 .7
5 .U 5 .7
5 .1
9 .7
1 .6
1 .6
3 .7
3 .9
6 .0
M
7 .9
8.0
9 .2
9 .6
1 .5
1 .6
3 .3
3 .7
6 .1
6 .3
8 .2
8 .Ii
9 .5
9 .9
10.5
27
1 1 .8
1 2 .5
1 .5
3.11
6 .0
6 .5
8.1i
8.9
9 .6
1 0 .ii
1 0 .9
Ii75
183
F
3.1
1 .6
1 1 .0
180
F
F
1 .7
9 .3
1<
6
7
K
10 .5
7
lo ll
M
Il
3
OS 101
V T II
Grand av.
by sex
Grand av.
a l l fis h
2
I
j-CS Sr o u P
I
( I - ircacture; *' - n a tu re " a les;
1 .3
1 3 .6
1 .5
1 .6
2 .Ii
1 .6
3 .1
l.L
3 .0
1 .6
3 .5
3 .5
ti.i
6 .1
8 .L
5 .7
3 .7
6.0
6 .1
6.3
8 .0
0 .2
e .t
9 .7
9.9
1 1 .5
n .8
1 1 .8
10.7
9.L
10.9
1 0 .5
11.1
ic.9
11.8
1 8 .1:
12.8
13.6
12.5
13.6
1 2 .ii
1 2 .6
-
30 -
s ix th - 1 0 .9 ; s e v e n th -1 2 .Itj e ig h th - 1 3 «6.
H azzard (1936) s tu d ie d th e grow th-
o f 26 U tah chubs from F is h L ake, U ta h .
T h e ir average c a lc u la te d t o t a l
le n g th s a t th e end o f . e a c h y e a r o f l i f e f o r th e f i r s t £ y e a rs were 1 ,3 ,
6 . 6 , and 7«lt in c h e s r e s p e c t i v e l y .
3»$,
The F is h Lake chubs were
com parable i n le n g th a t th e second annulus w ith th e Hebgen Lake sp ecim en s.
T h e re a fte r th e Hebgen Lake specim ens grew more r a p id ly ,
ACKNOWLEDGMENTS
The w r i t e r e x ten d s th a n k s t o th o s e in d iv id u a ls and a g e n c ie s t h a t
a s s is te d in t h i s in v e s tig a tio n .
D r. C. J . D. Brown d ir e c te d th e s tu d y
and h e lp e d i n p re p a rin g th e m a n u sc rip t.
B ishop c o l l e c t e d th e 19ii8 d a ta .
w ork.
Mr. R. A. Hays and Mr. C. G.
Mr. R . K night a s s i s t e d w ith th e f i e l d
Mr. F . J a n s , Mr. D. R id le y , and Mr. F . M ille r , r e s o r t o p e ra to rs on
Hebgen Lake, g e n e ro u sly p ro v id e d b o a ts and dock f a c i l i t i e s .
The Montana
F is h and Game d ep artm en t p ro v id e d f i n a n c i a l su p p o rt th ro u g h i t s D in g e llJohnson Program and th e Montana S ta te C o lleg e A g r ic u ltu r a l E xperim ent
S t a t i o n f u r n is h e d c e r t a i n equipm ent.
SUMMARY
1.
The b io lo g y o f th e U tah chub i n Hebgen Lake, Montana was s tu d ie d
i n 19I4.8 and in 19^3-193^«
2.
The chub was th e most abundant s p e c ie s o f f i s h i n th e la k e .
3.
G en eral s e a s o n a l d i s t r i b u t i o n o f th e chubs w as; c o n c e n tra te d i n
sh a llo w a re a s i n th e s p r in g , w id e ly d i s t r i b u t e d around th e la k e d u rin g
th e summer and f a l l , and c o n c e n tra te d i n th e d e ep e r a re a s i n th e w in te r .
-
Ito
31 -
I n I 9I48 stom ach a n a ly s is was made on $$ rainbow t r o u t , 70 brown
t r o u t and 163 ch u b s.
The p e rc e n ta g e s o f th e p r i n c i p a l fo o d ite m s by-
volume o f each s p e c ie s were as f o llo w s t rainbow t r o u t , in s e c ts -3 9 « 9 and
m ic ro c ru s ta c e a n s -28»2$ brown t r o u t , f is h - 6 9 ,2 and in sects-9 ® 9 $ chubs,
algae-li8o2 and m ic ro c ru s ta c e a n s -2 lt,3 .
Stomach a n a ly s is was made on 209 chubs c o l l e c t e d i n 1 9 5 3 -1 9 ^ .
T h e ir foods by volume w erej 36 p e rc e n t m ic ro c ru s ta c e a n s , 36 p e rc e n t i n ­
s e c t s , 19 p e rc e n t, h ig h e r a q u a tic p l a n t s , and 9 p e rc e n t d e b r is ,
6.
B ip te r a la r v a e and pupae made up a b o u t 75 p e rc e n t o f th e volume
o f in s e c t s i n 1953-1951t and m ay fly nymphs a b o u t 20 p e r c e n t.
7.
Most o f th e spawning i n 1953 and 195L o c c u rre d d u rin g l a t e June
and e a r l y J u ly .
8.
The 19514. spawning seaso n began i n May and e x te n d e d in to A ugust,
9.
Most spawning o c c u rre d in- te m p e ra tu re s above 5U° T1.
10.
A r i s e i n w a te r te m p e ra tu re s was a s s o c ia te d w ith .a n in c re a s e i n
th e p e rc e n t o f s p e n t fem ales c o lle c te d .
11.
F ry were found along most o f th e sh a llo w , p r o te c te d s h o r e lin e s .
1 2 . . Chub eggs were re c o v e re d on v a rio u s k in d s o f bottom s in c lu d in g
•g r a v e l, sa n d , s i l t , muck and d e t r i t u s , b u t most were re c o v e re d from sand
and g r a v e l.
13.
The number o f eggs p e r fem ale ra n g e d from 1 6 ,9 0 0 bo 62,IiOO and
av erag ed UO,750.
lU .
The average t o t a l le n g th o f young chubs i n 1953 in c re a s e d from
0 .8 in c h i n A ugust t o 1 .3 in c h e s i n O c to b er.
y
-
15.
y e ars.
^
on
16.
32 -
S ex u al m a tu r ity was a t t a i n e d by some m ales a t th e age o f th r e e
A few fem ales re a c h e d s e x u a l m a tu r ity a t th e age o f f o u r y e a r s .
The av erag e c a lc u la te d t o t a l le n g th s f o r each y e a r o f l i f e b ased
specim ens w as: f i r s t - 1 . 6 in c h e s ; s e c o n d - 3 . t h i r d - 6 . 1 ; f o u r th - 8 .2 ;
f i f t h - 9 . 7; s ix th - 1 0 .9 ; seventh-12»U ; e ig h th - 1 3 .6 .
LITERATURE CITED
D a v is, H. S .
I 9I4O. L aying th e fo u n d a tio n s o f f i s h e r y management.
C u l t u r i s t , No. 9 0 :1 -1 3 .
P rog. F is h -
H azzard, A. S .
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