The food of rainbow trout, brown trout and brook trout fry and fingerlings from five southwestern
Montana streams
by James P Fry
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
Montana State University
© Copyright by James P Fry (1960)
Abstract:
Samples of rainbow trout (Salmo qairdneri), brown trout (Salmo trutta) and brook trout (Salvelinus
fontinalis) fry and fingerlings were obtained for stomach analysis during the spring and summer of
1959 from five Southwestern Montana streams. An attempt was made to secure samples from the time
trout began to feed until they reached a length of approximately 4 inches. Stomachs from 356 rainbow
trout, 356 brown trout and 116 brook trout were examined. The predominant food of all three species
of fish was the larva of Tendipedidae, although Baetidae was nearly as abundant in the brook trout
stomachs. THE FOOD OF RAINBOW TROUT, BROWN TROUT AND BROOK TROUT
FRY AND FINGERLINGS FROM FIVE' SOUTHWESTERN MONTANA STREAMS
by
JAMES P. FRY
-5/
A THESIS
Subm itted to the Graduate' F a c u lty
in
■ p a r t i a l f u l f i l l m e n t of th e re q u ire m e n ts
f o r the deg ree of
M aster of S c ie n ce in F is h and W ild lif e Management
at
Montana S t a t e C ollege
Approved:
in in g Committee
Dean, G ra d u a te /D iv is io n
Bozeman, Montana
J u n e , 1960
Table o f C ontents
Page
A bstract . . .
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I n tr o d u c t i o n .................. ......................
Methods
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5
D e s c r ip tio n of Study Areas . . .................. . .................. . . . . . .
6
R e s u lt s
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ID
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Rainbow Trout
TO
Brown T r o u t ...................................
20
Brook T r o u t ..........................
29
D is c u s sio n ..................................................... ^
Summary
.
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
L i t e r a t u r e C ite d . ........................... . ......................
. . . . . . . . .
29
35
37
-3-
A b s tr a c t
Samples of rainbow t r o u t ('Salmo q a i r d n e r i ) , brown t r o u t (SaImo
t r u t t a ) and brook t r o u t ( S a lv e lin u s f o n t i n a l i s ) f r y and f i n g e r l i n g s
were o b ta in e d f o r stomach a n a l y s i s d u rin g the s p rin g and summer of
1959 from f iv e Southw estern Montana s tre a m s . An a tte m p t was made to
s e c u re samples from the time t r o u t began to feed u n t i l th ey reached
a le n g th of a p p ro x im a te ly 4 inches.. Stomachs from 356 rainbow tro u t*
356 brown t r o u t and 116 brook t r o u t were examined.. The predom inant food
o f a l l thr.ee s p e c ie s of f i s h was th e la r v a of Tenddipedidae, a lth o u g h
B a e tid a e was n e a r l y as abundant in th e brook t r o u t stom achs.
r
—4 —
I n tr o d u c ti o n
Very few w orkers have r e p o r te d s u b s t a n t i a l in fo rm a tio n on the food
of t r o u t l e s s than 4 in c h e s in le n g th .
Clemens (1928) s tu d ie d the stomach
c o n te n ts of 155 small brook t r o u t ( S a l v e lin u s f o n t i n a l i s ) and seven small
rainbow t r o u t (.Salmo q a i r d n e r i ).
R ick er (1930) examined stomachs from 41
small brook t r o u t , w hile Hazzard and Madsen (1933) s tu d ie d th e food of 48
sm all c u t t h r o a t t r o u t ( Salmo c l a r k i ).
The p r e s e n t study was i n i t i a t e d d u rin g th e s p rin g of 1959 in which
j u v e n i l e rainbow t r o u t , brown t r o u t (Salmo t r u t t a ), and brook t r o u t were
c o l l e c t e d f o r stomach a n a l y s i s from f i v e Southw estern Montana stre am s.
An
a tte m p t was made to sec u re samples from th e time t r o u t began to feed u n t i l
they reached a le n g th of a p p ro x im a te ly 4 in c h e s .
The f i r s t c o l l e c t i o n was
made A p ril 22 and su bsequent c o l l e c t i o n s were secured a t about 2 week
i n t e r v a l s te r m in a tin g September 22.
Stomach a n a ly s e s were made on 356 rainbow t r o u t , 356 brown trout,- and
116 brook t r o u t .
R e s u lts compare the food of the d i f f e r e n t s p e c ie s in r e ­
l a t i o n to l o c a t i o n and d a te of c a p tu r e .
The w r i t e r i s in d e b te d to Dr. C. J . D. Brown, who su g g ested the stu d y
and a s s i s t e d in p r e p a r a t i o n of the m a n u s c rip t.
Dr. R. C. F roeschner gave
v a lu a b le a id in th e i d e n t i f i c a t i o n of i n s e c t s .
Mr. A. C. Fox, Mr. Jack
Heaton and my w ife , Gayle R. F ry , p ro v id ed a s s i s t a n c e in th e f i e l d .
Montana S t a t e C o lleg e A g r i c u l t u r a l Experiment S t a t i o n f u r n is h e d some
f i n a n c i a l a id and equipment.
The
-5 -
Methods
C o lle c ti n g was accom plished d u rin g the d a y lig h t hours (8 :0 0 a.m. to
7 :3 0 pom,) .
The time r e q u ir e d f o r each c o l l e c t i o n was 1-3 h o u rs.
E a rly
in th e season t r o u t f r y and f i n g e r l i n g s ( u s u a l l y l e s s than 3 in ch es in
le n g th ) were c a p tu re d w ith a 4 - f o o t "common sense" seih d ( o n e -e ig h th -in c h
mesh) o p e ra te d by one p e rs o n .
L a te r i n th e seaso n , when f i s h were u s u a ll y
in ex cess of 3 in c h e s , an 8 - f o o t s e in e ( o n e - f o u r th - in c h mesh) was employed.
This was o p e ra te d by two p e rso n s and was e f f e c t i v e in f a s t e r , deeper w a te r,
where many of th e se f i s h were found.
An e l e c t r i c s h o c k e r - ( d . c . ) was used
f o r p ro c u rin g the l a s t c o l l e c t i o n from th e Madison R iv e r.
A ll specimens were immersed in a s o l u t i o n of 1 0 -p e rc e n t fo rm alin
im m ediately a f t e r c a p tu r e .
A few f i s h were observed a f t e r immersion and
none was seen to r e g u r g i t a t e food.
A lso , no r e g u r g i t a t e d food was found
in the c o l l e c t i o n j a r s a f t e r p r e s e r v a t i o n .
F ish were p la c e d in a fr e s h
s o l u t i o n of 1 0 -p e rc e n t f o r m a lin , I or 2 days a f t e r c a p tu r e , and then
s to r e d f o r l a t e r stu d y .
Water te m p e ra tu re s were taken a t the time of each f i s h c o l l e c t i o n .
T u r b id ity was d eterm in ed only on th o se c o l l e c t i o n d a te s when the w ater
was n o t i c e a b l y turbid=
Where numbers p e r m itte d , 20 f i s h of each s p e c i e s , from each c o l l e c t ­
io n , were randomly s e l e c t e d and t h e i r stomachs examined=
When l e s s than
20 specimens were p r e s e n t in a c o l l e c t i o n , a l l were examined.
Each s p e c i ­
men was opened on th e v e n t r a l s id e and th e esophagus and stomach were r e ­
moved f o r a n a l y s i s .
The organisms found were determ ined to f a m i l i e s ,
-6-
whenever p o s s i b l e , and counted.
A ll D ip te ra la r v a e were i d e n t i f i e d to
fa m ily , however pupae and a d u lts , were p la c e d in the c a te g o ry of m is c e l­
lan eo u s D i p t e r a .
I t i s p ro b a b le t h a t a la r g e p ro p o r tio n o f thosb p la c e ^
in t h i s c a te g o ry belonged to the fam ily T e n d ip ed id ae.
Organisms, e x c lu s iv e
o f t e r r e s t r i a l i n s e c t s and fish-,- were c l a s s i f i e d u sin g Ward and W hipple's ■
Fresh Water Biology (Edmondson, 1959).
T e r r e s t r i a l i n s e c t s were i d e n t i f i e d
u sin g An I n t r o d u c t i o n to Entomology (Comstock, 1957)..
..Weights or volumes were n o t d eterm in ed because of th e small q u a n ti­
t i e s p re sen t.
D e s c r ip tio n of Study Areas
Five c o l l e c t i n g s t a t i o n s . w e r e e s t a b l i s h e d as f o l l o w s :.
Madison R iver
d ra in a g e - North Meadow Creek, Madison R iv er p ro p e r, South Fork of the
Madison R iv e r, Duck Creek; G a l l a t i n R iv er d ra in a g e - T rout Creek.
S ta tio n s
were g e n e r a l l y lo c a te d in th e sh allo w , p r o t e c t e d p o r t i o n s of stream s.
With
few e x c e p tio n s f i s h were c a p tu red in slow moving w a te r, l e s s than 2 f e e t
deep, where bank v e g e t a t i o n was submerged or overhung i n t o the stream , q-r
where a q u a ti c v e g e t a t i o n was abundant.
The s m a lle s t f i s h were cap tu red in
v e ry sh allo w w a te r, u s u a l l y in a s s o c i a t i o n w ith sand or s i l t bottoms.
Col­
l e c t i o n s were most r e a d i l y o b ta in e d from a r e a s where s p r in g - s e e p s e n te r e d
th e stream .
.As the season p ro g re s se d and f i s h became l a r g e r , they were
a l s o c a p tu re d in d e e p e r, f a s t e r w a te r.
L arger f i s h were found more common­
l y b en eath u n d e rc u t banks or in p o o ls , r a t h e r than in sh allo w sandy a r e a s .
North Meadow Creek
This s t a t i o n in c lu d e d about 800 l i n e a l f e e t of r e l a t i v e l y s t r a i g h t
s tre am , which had an av erag e width of 17 f e e t .
The av erage depth was 9
in c h e s and the v e l o c i t y ranged from 0 .0 to 2 .5 f e e t p e r sgtipnd.
The
maximum w ater te m p e ratu re was 69° F. on June 23 and the minimum was 50° F.
on September 22.
There was no n o t i c e a b l e t u r b i d i t y and w a ter l e v e l s r e ­
mained r e l a t i v e l y s t a b l e .
The bottom was pred o m in an tly gray,el and ru b b le
w ith small a r e a s of sand.
A few sm all s p r in g - s e e p s were p r e s e n t and th e s e
were choked w ith w a te r c r e s s ( R o rip p ia i s l a n d i c a ).
Stream banks were
b o rd ered w ith s c a t t e r e d w illow s ( S a lix s p . ), g r a s s e s , and sedges th a t
overhung i n t o the w a te r.
The su rro u n d in g a re a was f l a t p a s tu r e la n d .
Madison R iver
This s t a t i o n in c lu d e d a r e l a t i v e l y s t r a i g h t p o r t i o n of stream along
th e n o r th bank of the r i v e r .
I t was a p p ro x im a te ly 900 f e e t long and
ab o u t 10 f e e t wide e x ce p t a t the lower end where i t in c lu d e d a small i s ­
la n d .
Here th e w idth was ap p ro x im ately 200 f e e t .
The average depth was
10 in c h es and v e l o c i t i e s ranged from 0 .0 to 4 .0 f e e t p e r second.
The
maximum w a ter te m p e ratu re was 71° F. on J u l y 25 and the minimum was 60° F.
on June 23.
There Was no n o t i c e a b l e t u r b i d i t y .
Water l e v e l s v a rie d con­
s i d e r a b l y due to i r r e g u l a r r e l e a s e s from Hebgen R e s e r v o ir , which was l o ­
c a te d o n e -fo u rth m ile upstream from the s t a t i o n .
Bottom m a t e r i a l s con­
s i s t e d l a r g e l y of b o u ld e r s , ru b b le and g ra v e l w ith a r e a s of sand and s i l t
a d ja c e n t to the i s l a n d .
Some s t r i c t l y a q u a ti c v e g e ta tio n was p r e s e n t and,
in a d d i t i o n to t h i s , g r a s s e s and sedges alo n g the edges of th e is l a n d were
in u n d a te d d u rin g p e r io d s of high w a te r.
c u t and bord ered w ith g r a s s e s and s ed g e s.
The North r i v e r bank was s h a rp ly
The su rro u n d in g a re a was a
—8 —
s t e e p , rocky canyon p a r t l y covered w ith co n ifers=
Ch August 15, an earth q u ak e made a c c e s s to t h i s s t a t i o n i m p r a c t i c a l .
As a r e s u l t , th e l a s t c o l l e c t i o n was made 10 m ile s below th e o r i g i n a l
c o l l e c t i n g s t a t i o n and 5 m ile s below a l a n d s l i d e t h a t dammed the r i v e r ,
The w ater l e v e l was reduced about 2 f e e t from normal and th e flow in t h i s
a re a was l i m i t e d to w ater from a few s p r in g s and some seepage through the
la n d slid e.
The w ater te m p e ratu re was 54° F. and th e r e was n o tic e a b le
tu rb id ity .
F ish .w e re c o l l e c t e d from rem aining p o ck ets o f w ater beneath
a b r id g e .
South Fork of the Madison R iver
This s t a t i o n c o n ta in e d p a r t s of two la r g e meanders of the r i v e r , and
was about 1,000 f e e t in le n g th .
I t in c lu d e d about 8 f e e t o f stream along
each bank e x ce p t f o r s e v e r a l p o o ls over 3 f e e t deep.
These were n o t i n ­
cluded in the s t a t i o n because c o l l e c t i n g methods were n o t e f f e c t i v e in
deep w a te r .
The average d epth was 10 in c h es and v e l o c i t i e s ranged from
0 .0 to 3 .5 f e e t p e r second.
The maximum w ater tem p e ratu re was 56° F. on
J u l y 25 and th e minimum was 43° F. on June 23.
There was no n o tic e a b le
t u r b i d i t y ex cep t on September I , a f t e r the e a rth q u a k e , when i t was 70
p .p .m .
Water l e v e l s d id n o t vary a p p r e c ia b ly .
Bottom ty p e s included
g ra v e l and s e v e r a l la r g e a r e a s of sand in th e r i f f l e a r e a s and s i l t in
th e backw ater a r e a s .
Water b u tte r c u p ( Ranunculus s p . ) was abundant in
the s m a lle r backw aters and on some s h e l t e r e d sandy a r e a s .
s e d g e s, r u s h e s , and w illow s l in e d the r i v e r banks.
u n d e rc u t, a s much a s 5 f e e t .
T a ll g r a s s e s ,
Some of th e banks were
The su rro u n d in g area was a r e l a t i v e l y f l a t
-9-
v a l l e y f l o o r , l a r g e l y covered w ith w illo w s, and c o n if e r s were predominant
a t h ig h e r e l e v a t i o n s .
Duck Creek
This c o l l e c t i n g s t a t i o n in c lu d e d a 1 5 0 -fo o t s e c tio n o f r e l a t i v e l y
s t r a i g h t stream w ith an average w idth o f 35 f e e t and an av erag e d epth of
11 in c h e s .
V e l o c i t i e s v a r ie d from 0 .0 to 3 .0 f e e t p e r second.
The maxi­
mum w ater te m p e ratu re was 69° F. on J u l y 25 and the minimum 54° F. qn
September I*
There was no n o t i c e a b l e t u r b i d i t y ex cep t on September I ,
a f t e r th e e a rth q u a k e , when i t was 64 p .p .m .
tiv e ly stab le.
p o s i t s of sand.
Water l e v e l s remained r e l a ­
The bottom was p re d o m in a n tly g ra v e l w ith a few la rg e de­
S i l t was p r e s e n t in th e backwater a r e a s .
Dense beds of
w ater b u tte r c u p covered Jthehsandy a r e a s and c a t t a i l s and ru s h e s were
p r e s e n t along a few g r a d u a lly slo p in g b anks.
Most banks were s h a rp ly cu t
and bord ered by overhanging g r a s s e s and s ed g e s.
was b e n ea th a highway b r id g e .
A p o rtio n of th is s ta tio n
The su rro u n d in g area in c lu d e d g e n tly r o l l i n g
f o o t h i l l s n e a r one edge of th e Madison R iv er v a l l e y , where v e g e ta tio n was
p re d o m in an tly c o n ife ro u s f o r e s t and sagebrush p r a i r i e .
T rout Creek
This s t a t i o n in c lu d e d about 1,500 f e e t of meandering stream w ith an
average w idth of 5 f e e t , and an av erag e d e p th of 8 in c h e s .
ranged from 0 .0 to 2 .5 f e e t p e r sedond.
The v e l o c i t y
The maximum te m p e ratu re was 60° F.
on J u l y 21 and th e minimum was 45° F. on A p ril 22.
T u r b i d i t i e s were 10-12
p .p .m . d u rin g June and J u l y b u t were n o t measured in August, when no
n o t i c e a b l e t u r b i d i t y was p r e s e n t .
I
Holton (1952) r e p o r te d th e occurrence
-10-
of f l a s h flo o d s in t h i s stre am , which caused c o n s id e ra b le washing of the
stream banks and sc o u rin g o f the bottom .
th e course of t h i s s tu d y .
Bottom m a t e r i a l s in clu d ed sm all g ra v e l in
r i f f l e a re as,, and sand and s i l t in p o o ls .
c re a se d n o t i c e a b l y from A p ril to August.
r u n o f f and s p rin g s e e p s .
p la n t.
No such flo o d s o ccu rred du rin g
Areas of sand and s i l t i n ­
The w ater so u rce was i r r i g a t i o n
W a te rc re ss was th e c h i e f submerged a q u a tip
This was c o n fin ed to the sandy a r e a s in e a r l y summer b u t choked
a la r g e p o r t i o n of thev stream by autumn.
Overhanging banks were p r e ­
dominant and were l in e d w ith w illow s and sed g es.
In the f a l l , sedges
formed a canopy over p o r t i o n s of the stream in the upper end of the
statio n .
The e n t i r e s t a t i o n la y in a small r a v in e , surrounded by f l a t
farm land.
R e s u lts
A t o t a l o f 829 t r o u t f r y arid f i n g e r l i n g stomachs were examined.
These came from th e fo llo w in g l o c a l i t i e s : . North Meadow Greek - IOS1 r a i n ­
bow t r o u t , 120 brown t r o u t ; Madison R iv er - 80 rainbow t r o u t , 79 brown
t r o u t ; South Fork of th e Madison R iv er - 88 rainbow t r o u t , 92 brown tro u t.;
Duck Creek - 80 rainbow t r o u t , 65 brown t r o u t ; Trout Creek - 116 brook
tro u t.
Only fo u r stomachs were empty and th e se were n o t in c lu d e d in the
to ta ls.
Rainbow Trout
No a tte m p t was made to d i s t i n g u i s h between rainbow and c u t t h r o a t
t r o u t , however c u t t h r o a t t r o u t were r a r e in the c o l l e c t i o n a r e a s and th e re
i s l i t t l e p r o b a b i l i t y any were taken ini th e c o l l e c t i o n s .
—11 —
N orth Meadow Creek (Table I ) .
The most abundant organisms in the
rainbow t r o u t stomachs were the la r v a e o f T e n d ip ed id ae0
The number of
th e s e organisms p e r stomach ranged from 58 to 90 p e r c e n t o f the t o t a l in
a l l c o l l e c t i o n s ex cep t on September 22, when i t was only 30 p e r c e n t.
They
o c cu rred in 95-100 p e r c e n t o f the stomachs in a l l c o l l e c t i o n s b u t the one
taken on J u l y 24 where th ey o ccu rred in only 80 p e r c e n t.
M iscellan eo u s
D ip te ra w e re ,n e x t in abundance in a l l c o l l e c t i o n s ex cep t the one procured
J u ly 24.
The number o f th e s e organisms p e r stomach ranged from 5 to 21
p e r c e n t of the t o t a l .
The p e rc e n ta g e s in c r e a s e d as th e seaspn p ro g re s se d
w ith a consequent i n c r e a s e in s i z e of f i s h , however the number of stomachs
in which th ey o c c u rre d , in each c o l l e c t i o n follow ed no a p p a r e n t p a t t e r n .
A. la r g e number o f a p h id s o ccu rred in the J u ly 24 and September 22 c o l­
le c tio n s.
This may be accounted f o r by r a i n s d u rin g and j u s t p reced in g
c o l l e c t i n g on th o se d a te s which p ro b a b ly washed them i n t o th e stream from
overhanging v e g e t a t i o n .
Other organisms which in c lu d e d over 5 p e r c e n t of
th e t o t a l number o f item s p e r stomach were:
B a e tid a e , D y tis'c id a e , Hydrop-
t i l i d a e , T ip u lid a e l a r v a e , and D ixidae la r v a e .
Madison R iv er (Table I I ) .
Lake d w e llin g C ladocera and Copepoda com­
p r i s e d a m ajor p o r t i o n of th e food in th r e e c o l l e c t i o n s .
Copepoda was th e
predom inant food in the J u l y 9 c o l l e c t i o n , where i t comprised 80 p e rc e n t
of th e t o t a l number of item s p e r stomach and was found in 17 of the 20
f i s h examined from t h a t c o l l e c t i o n .
I t was followed in abundance by
C la d o c e ra , w ith 13 p e r c e n t ( found in 13 f i s h ) .
C ladocera was th e most abundant organism .
In th e August 10 c o l l e c t i o n ,
I t c o n s t i t u t e d 65 p e r c e n t of the
t o t a l number of organisms p e r stomach, follow ed by Copepoda w ith 26 p e r c e n t .
-1 2 T a b le I ,
The f o o d o f r a i n b o w tr t p u t from N o r th Meadow C re e k (1 9 5 9 ) e x ­
p r e s s e d a s num ber o f i t e m s p e r sto m a c h and p e r c e n t a g e o c c u r r e n c e .
June 23
T o tal f i s h
J u ly 24
20
Oo9—1o6
11
.....................
Range in t o t a l
le n g th ( i n c h e s ) . I . 0 - 1 . I
Average le n g th
(in c h e s ) . , . .
J u ly 14
I . O'
. , .
I . 1 -2 .5
1.2*2 .4
I . -5-3.0
1 .6
1.7
2 .3
§
8
O.
0.09
9
0.45
0 .0 9
9
9
. 4-3
8
£
4-3
A
C
CD_____ CU
O1
s
W
8
O l -.
0.05
5
0.20
0.05
5
0.05
5
1
2
8
.
CU
CD
4->
A
CU
1
2
0.35
C
CU
H
CU
CL,
O
CO
2
CU
P
0
CM
I . 9 -2 .9
2,.4
CD
CD
CU •
CD
4-3
Ph
C
CD_____ m
1
2
0.0&
8
CL,
5
4-3
8
3•
s
I
£
%
cu
a,
0.18 12
0.1 2 12
0.15 10
0.82 73
0 .0 9
0.-55 40
9
0.05
5
0.18 6
0.18 12
0.41 12
0 .80 55
0 .10 10
0 .40 30'
0.05 5
0.05 5
1.70 75
0 .2 0 15
0.65 40
0.41 29
0.12 12
0.53 24
0.05
5
0.10 10
0
CO
0
A quatic
Nonid td 0000090000
O ligochaeta . . . . .
O stracoda . . . . . . .
Copepoda . . . . . . . .
Isopoda ooooooooo
Amphipoda . . . . . . .
Ephejneroptera
B ae tid a e . . . . . . .
Epheftiere l l i d a e .
T r ic o r y th id a e . .
P le c o p te ra
Nemouridae . . . . .
C o le o p tera
D y tis c id a e . . . . .
Elmidae 00*0000*
T r ic h o p te ra
Psychomyiidae . .
Hydropsychidae .
H y d ro p tilid a e . .
Lim nephilidae .-.
Brachycent r i d a e .
m isc. T rich o p . .
D ip te ra
. T ip u lid a e . . . . . .
• Psychodidae . . . .
D ixidae *00*0000
S im u liid a e . . . . .
Tendjbpedidae . . .
S tra tio m y id a e . .
17
O)
4-3
1
20
CD
Cn
8
S e p t. 22
I . ?
CU
Item
S e p t. 4
20
Aug. 10
20 -
30
0.2 4 18
0 .0 5
5
0 .2 0 10
1.71 '19;
0.15 15
0.09
9
0.05
5
. 0.05
5
0 .2 0 20
0.10 10
0.15 15
21.35.100
0 .10 1.0
0.-05 5
Q.65 30
0.0 5 5
0 .0 5 L5
0.05
0.18 18
7.64.100
0.10 100.45 30
0.30 20
5
0.10 10
0U65 35
16.35.100
0.30 15
0.05 5
0.35 30
1.30 65
13.25 95
0.05 5
0.35 25
17.20 95
0.05 5
1 .8 2 65
0.53 35
0.12 12
0.06 6
2 .5 3
0.0 6
2 .1 2
0.24
8.71
0.94
35
6
35
24
82
47
13-
Table I (c o n tin u e d ) .
I
S
Ck
3.
Ck .
3
Ck
S e p t. 22
fH
<u
Xi
I
3
'ercentage |
S
a.-
e rc en ta g e
s
fH
<D
-Q
S e p t. 4
umber
%
0
Aug. 10
e rc en ta g e
H
Q
J u l y 24
e rcen tag e
Item
CU
Cn
CU
J u ly 14
0
U)
CU
-P
A
§O
0
0
Ck
s
umber
June 23
-
D ip te ra c o n t,
Musidae . . . . . . . .
misc ^ --Diptera . .
A cari . . . . . . . . . . .
p la n t m a te ria l ..
u n id e n tifie d . . .
0.0 9 9
1 . 00.1IOD-.
0 .0 9 "9",
0.09
T e rre stria l
Thysanoptera
T h rip id a e . . . . . . 0.18
Homoptera
Aphididae . . . . . .
G ic a d e llid a e . . .
L ep id o p tera
M ic ro p te ry g id a e .
Hymenoptera
Form icidae . . . . . 0 .0 9
T o tal
10.99
1.15 45
0.30 15
0.7 0 50
4 .1 5 90
0.1 0 10
5
9
0.05 ■:5
3 .9 0 85
0.65 15
0.05
0.2 0 15
6.20.100
0.85 10
10
0 .2 9 18
4 .0 0 59
0.12 12
5
'
9
4 .2 5 65
0.1 0 10
0.45 15
0.45 30
3 .0 6 65
0.1 0 10
9
0.05
23.75
28.05
22.20
0 .06
5
2 9 .7 0
28.74
6
—1 4 T ab le I I .
The f o o d o f r a i n b o w t r o u t from t h e M adison R i v e r (1 9 5 9 ) e x ­
p r e s s e d a s num ber o f i t e m s p e r sto m a c h and p e r c e n t a g e
o ccurrence.
Ju ly 9
T o tal f i s h . . . . . .
Item
Aug. 24
20
20
20
0 .8 —1 . 3 .
0 .9 -1 .9
I . 2 - 2 .2
I . 8 -2 .7
1. 0
1.1
1. 5
2 .2
'
CU
o
A
0
I
S
A quatic
C ladocera . . . . . . .
Copepoda . . . . . . . .
Ephemeroptera
B sstidsG «000000
P le c o p te ra
Nemouridae . . . . .
T ric h o p te ra
Hydropsychidae .
H y d ro p tilid a e . .
L im n ep h ilid ae . .
G lo sso so m atid ae.
D ip te ra
S im u liid a e . . . . .
Tendipedidae ...raise. D ip te ra . .
Ac s r i 0«'oooooo 0*0
u n id e n tifie d . . . .
Aug. 10
20
Range in t o t a l
le n g th ( i n c h e s ) .
Average le n g th
( in c h e s ) . . . . . . .
•1
)
J u l y 25
2 .3 5
15.15
O„75
0.55
CO
-P
0
CO
CO
C
0
A
0
C
0
A
0
C
0
S
0,.
I
,2
§
O,-
§
2
5
65
85
",
5 .8 0
40
59.45
23.65
95
95
1.05
5
35
40
0.05
5
4 .9 5 95
5 .8 5 100
0 .1 0 10
0 .1 0 10
T e rre stria l
Homoptera
C ic a d e llid a e . . .
T o tal
0
0.1 0
10
2.15
4 .2 0
80
80
0.05
18.80
16.85
90.65
5
A
CU
_Q
@
2
0
O")
0
-P
C
0)
O
S
a,
4 9 .1 0 100
0 .2 5
20
0 .7 0
1.05
0.2 0
0.1 0
45
60
10
10
5 .4 5 85
7 .5 5 100
1.35 40
0.05
5
0.45
15
66.25
-15-
Bo th organisms o ccu rred in 95 p e r c e n t of the stomachs from t h a t c o l l e c t i o n .
Copepoda was second in abundance in th e J u l y 25 c o l l e c t i o n , being p r e s e n t
i n 40 p e r c e n t of the stom achs.
The p re s e n c e of th e se p l a n k t e r s was n o t
s u r p r i s i n g s in c e th e c o l l e c t i n g s t a t i o n was only a s h o r t d i s t a n c e down­
stream from Hebgen R e s e r v o ir .
They undoubtedly in h a b ite d the r e s e r v o i r
and passed over th e s p illw a y a t Hebgen Dam.
They were co m p letely a b se n t
from the August 24 c o l l e c t i o n fo llo w in g th e e arth q u a k e , which was p ro ­
cured 10 m ile s downstream from th e c o l l e c t i n g s t a t i o n , j u s t below a la n d ­
s l i d e which dammed the r i v e r .
Except f o r th e s e p l a n k t e r s , Tendipedidae
la r v a e and m is c e lla n e o u s D ip te ra were th e predom inant food organisms in
a l l ex cep t the c o l l e c t i o n taken on August 24.
M isc e lla n e o u s D ip te ra ex­
ceeded Tendipedidae la r v a e in abundance on J u ly 25 and August 10.
B ae tid a e
was th e predom inant food organism in th e f i s h taken on August 24.
This
fam ily o ccu rred in a l l f i s h , and the number o f organisms p e r stomach com­
p r i s e d 74 p e r c e n t of th e t o t a l .
In t h i s c o l l e c t i o n T endipedidae la rv a e i n ­
cluded 11 p e r c e n t and a ls o o ccu rred in a l l f i s h .
bundance by';
I t was follow ed in a -
S im u liid a e l a r v a e , m is c e lla n e o u s D ip te ra and H y d ro p tilid a e ,
re sp ec tiv e ly .
South Fork of th e Madison R iver (T able I I I ) .
Tendipedidae la rv a e
o c cu rred in a l a r g e r p e rc e n ta g e of the stomachs than d id o th e r organisms
in a l l c o l l e c t i o n s from t h i s s t a t i o n and were a ls o th e most abundant
organisms in th e stomachs ex cep t f o r th e c o l l e c t i o n taken on J u ly 25,
where C ladocera comprised 50 p e r c e n t o f th e t o t a l number of organisms p e r
stomach.
C ladocera o ccu rred in only 6 of th e 20 stomachs from t h a t c o l ­
l e c t i o n and one of th e se co n tain ed 188 o f th e se organism s.
Cladocera con-
-16T ab le I I I .
The f o o d o f r a i n b o w t r o u t from S o u th F ork o f t h e M adison R i v e r
(1 9 5 9 ) e x p r e s s e d a s n um ber o f i t e m s p e r s to m a c h and p e r c e n t a g e
o ccu rren ce.
June 23
T otal f i s h . . . . . .
Range, in t o t a l
le n g th ( i n c h e s ) .
Average le n g th
f in c h e s @ @* »■"»»
J u ly 11
20
8
0 .9 - 1.2
A quatic
H irudinia . . . . . . .
Cladocera . . . . . . .
Ostracoda . . . . . . .
Copepoda . . . . . . . .
Amphipoda ..............
Ephemeroptera
H eptageniidae . .
S ip h lo n u iid a e . .
B a etid a e . . . . . . .
Ephem erellidae .
P le c o p te r a
Nemouridae . . . <, .
T richoptera
H y d ro p tilid a e . .
L im nephilidae . .
B rach ycen trid ae.
m is c . T r ichop. .
D iptera
S im u liid a e . . . . .
Tendipedidae . . .
m iscT D ip tera . .
A cari . . . . . . . . . . .
Gastropoda ............
20
0 .9 -1 .3
0 .9 -1 .6
0 .9 -2 .5
I . 3 —2 . 3
1.1
1.2
1 .4
1.8
CD
I2
CU
CTl
-P
CU
CU
Cn
-p
CD___ CD
CD
CD
____ -P
CD____CD
CU
§
2
2
§
2 .5 0 15
10.35 30
0.45- 5
63
13
0 .0 5 5
0 .3 0 15
0 .0 5 5
0 .0 5
0 .1 5 5
1 .0 0 40
0 .1 5 15
9
S
CU.
0 .1 5 15
0 .1 5 15
CD
6
D
2
1 .4 0 60
0 .0 5 5
5
5
0 .1 0 5
0 .0 5 5
1 .3 0 65
0.05
0 .0 5
CD
CD
-P
CD
P
CD
CU.
0 ,2 5 15
0 .0 5
S1
5
1 .1 0 40
1 .0 5 60
0 .0 5 5
0 . 1 0 10
0 .1 3 13
19.63 100
0 .2 5 25
0 .1 3 13
0 . 1 0 10
18 .7 0 95
2 ,6 0 75
4 .5 0 70
3 .5 5 50
0 .1 5
T err estria l
Homoptera
Aphididae . . . . . .
Total
®
CU,
0 . 1 0 10
0 . 2 0 10
0 .7 5
0 .2 5
•Sept. I
20
CD
-P
C
CD
P
CD
CU
Aug. 10
20
I . Or
A
<L>
-Q
I
2
J u ly 25
0 .0 5 5
2 3 .7 0 90
0 .8 5 40
5
0 .1 0
2 1 .1 4
24.35
2 0 .7 0
9 .80 95
0 .4 0 30
cues 20
2 6 .5 0
5
0 .1 5 15
15.30
-1 7 -
s t i t u t e d 10 p e r c e n t of th e t o t a l number of organisms p e r stomach on J u ly
11, b u t o ccu rred in only th r e e o f the 20 stomachs from t h a t c o l l e c t i o n .
M isc e lla n e o u s D ip te ra were of minor abundance except in th e J u ly 11 and
J u l y 25 c o l l e c t i o n s when they made up 11 p e r c e n t and 17 p e r c e n t r e ­
s p e c t i v e l y of th e t o t a l number of organisms p e r stomach.
They occurred in
75 p e r c e n t and 50 p e r c e n t of the stom achs, r e s p e c t i v e l y .
B ae tid a e was
p r e s e n t in a l l c o l l e c t i o n s , and i t s numbers p e r stomach ranged from I to 9
p e r c e n t of th e t o t a l .
I t occurred in 15-65 p e r c e n t of th e stomachs.
H y d ro p tilid a e and Lirtinephilidae were p r e s e n t only in th e c o l l e c t i o n taken
on September I , where each comprised 7 p e r c e n t of the t o t a l number of
organisms p e r stomach.
H y d ro p tilid a e o c cu rred in 8 of th e 20 stomachs
from t h a t c o l l e c t i o n , and Lim nophilidae i n 12.
Duck Creek (Table I V) .
Tendrpedidae la r v a e were th e most abundant
food organisms in th e J u ly 9 and J u l y 25 c o l l e c t i o n s .
They were p r e s e n t in
a l l c o l l e c t i o n s , w ith the number p e r stomach ran g in g from 19 to 63 p e r c e n t
o f th e t o t a l .
These p e rc e n ta g e s d e c re a se d as the season p ro g r e s s e d .
Mis­
c e lla n e o u s D ip te ra were predom inant i n th e August 11 and September I c o l ­
le c tio n s.
They were p r e s e n t in a l l c o l l e c t i o n s and t h e i r numbers per
stomach tanged from 26 to 55 p e r c e n t of th e t o t a l .
B a e tid a e occurred in
a l l c o l l e c t i o n s w ith a range of 3-13 p e r c e n t of the t o t a l and occurred in
30-45 p e r c e n t o f th e stomachs.
A v a r i e t y o f t e r r e s t r i a l i n s e c t s occurred
in a l l c o l l e c t i o n s , b u t were never v e ry abundant.
Lim nephilidae occurred
i n e i g h t of th e 20 stomachs from September I and c o n s t i t u t e d 9 p e r c e n t of
th e t o t a l number of item s p e r stomach in t h a t c o l l e c t i o n , b u t was n o t as
abundant in th e o th e r c o l l e c t i o n s from t h i s stream .
-18The f o o d o f r a i n b o w t r o u t from Buck C re e k ( 1 9 5 9 ) e x p r e s s e d a s
num ber o f i t e m s p e r s to m a c h and p e r c e n t a g e o c c u r r e n c e .
J u ly 9
J u ly 25
Aug. 11
S e p t. I
20
20
20
T otal f i s h ............
20
Range1in t o t a l
le n g t h ( i n c h e s ) .
0 .8 -1 .2
0 .9 -1 .3
Average le n g th
( in c h e s .............. ..
1 .0
1 .0
CU
Item
fH
CU
I
.S
Aquatic
Cladocera ............ ;
Ostracoda ..............
Copepoda .................
Ephemeroptera
B aetid ae ..............
' Lept o p h ie b ii d a e .
Ephem ereilidae .■
Hemiptera
C orixid ae ............
C oleoptera
D y t is c id a e ..........
T rich optera
H y d ro p tilid a e . .
L im nephilidae . .
raise. Trichop. .
D iptera
T ip u lid a e . . . . . .
S im u liid a e . . . . .
Tendipedidae . . .
Musidae .................
raise. D iptera . .
f i s h eggs ..............
p la n t m a t e r ia l . .
u n id e n tifie d . . . .
CU
H
CU
S
A.
IS
A
0 .5 5 30
I . 5 -2 .7
.9
2 .0
1 .3
CU
CU
C
CU
SC
0
CO
1'
t—
T a b l e IV .
A
CU
S
I2
CU
CU
C
CU
A
CU
A
0 .0 5 5
0 .1 5 10
0 .4 0 20
0 .1 0
10
0.2 0
5
1 .0 5 45
0 .8 0
35
0 .0 5
5
A
CU
CU
CU
C
CU
;
2
s
A
0 .0 5
5
1 .5 5 45
0 .2 0 15
0 .1 5 15
0 .1 5 15
0 .0 5
0 .3 5 15
12 .6 5 95
6 .0 0 80
0 .2 0
0 .1 0 JO
5
5
0 .0 5 5
5 .6 0 65
2 .9 0 65
0 .5 5 5
5
0 .10 10
0 .2 0
0.05
20
5
0.20 10
0.10
5
■ 6 .6 0 85
'' 0 .0 5
,5
11.45 100
0 .3 0 25-.
1 .1 5 40
0 .1 5 10
0 .1 0 10
2 .2 5 75
OilO 5
5 . 0 0 75
0 =05
5
5
-1 9 -
Table IV, c o n tin u e d .
Total
Number
Number
Percentage
5
0.10
5
15
0:10 10
0.10
10
0 .'05
5
5
10
0 .0 5
0.05
5
5
0.70
0.05
30
5
0.2 0 10
0 .5 0 25
0.10
10
0 .1 0
5
0.25
0.05
0.1 0
11.35
20.85
Percentage
Percentage
0.05
0.05
20.00
S e p t. I
Aug. 11
Number
T e rrestria l
Collembola
Entomobryidae . .
Thysanoptera
T h rip id a e ...........
Hbmoptera
Aphididae ...........
C ic a d e llid a e . . .
Hymenoptera
P la ty g a ste rid a e .
J u l y 25
Percentage
Item
Number
Ju ly 9
12.15
5
-20-
Brown Trout
North Meadow Creek (Table V).
Tendipedidae la rv a e were the p r e ­
dominant food organisms in small brown t r o u t stomachs from a l l c o l l e c t i o n s
from t h i s s t a t i o n , where t h e i r numbers p e r stomach ranged from 41 to 87
p e r c e n t of th e t o t a l .
P e rc e n ta g e s were s m a lle r as th e season p ro g r e s s e d .
These la r v a e o c cu rred in 95-100 p e r c e n t o f th e f i s h e x cep t in the Sep­
tember 22 c o l l e c t i o n , where thgy o c cu rred in only 80 p e r c e n t .
M is c e l-
<
lan eo u s D ip te ra were second in abundance in most c o l l e c t i o n s and the
number p e r stomach ranged from 5 to 21 p e r c e n t of t h e - t o t a l .
The p e r c e n t ­
age in c r e a s e d as th e season p ro g r e s s e d , b u t d ecreased to 11 p e r c e n t on
September 22.
They o ccu rred in 45-95 p e r c e n t of the f i s h , b u t t h e i r oc­
c u rre n c e follow ed no a p p a re n t p a t t e r n .
Aphids o ccu rred in la r g e numbers in
th e J u l y 24 and September 22 c o l l e c t i o n s , a s they did in the rainbow t r o u t
from t h i s stream .
ra in s.
These c o l l e c t i o n s were taken d u rin g and j u s t a f t e r
H y d ro p tilid a e was abundant in a l l c o l l e c t i o n s b u t th o se procured
on June 23 and J u ly 14.
I t c o n s t i t u t e d 5-19 p e r c e n t of the t o t a l number
o f item s in a l l c o l l e c t i o n s b u t th e l a t t e r two m entioned.
B aetid ae was
p r e s e n t in a l l c o l l e c t i b n s w ith 2-8 p e r c e n t of the t o t a l .
Madison R iver (Table VI ).
The food of small brown t r o u t was s i m i l a r
to t h a t of rainbow t r o u t , a t t h i s s t a t i o n below Hebgen Dam.
P la n k to n ic
C ladocera and Copepoda were p r e s e n t in a l l c o l l e c t i o n s e x c e p t the one p r o ­
cured on August 24.
C ladocera was th e most predominant food organism in
th e stomachs of f r y and f i n g e r l i n g s taken J u l y 9 and August 10.
I t made
up 67 and 77 p e r c e n t o f th e t o t a l number of organisms p e r stomach, r e ­
s p e c tiv e ly .
Copepodk o ccu rred in l a r g e numbers in the June 23 and J u ly 9
-2 1 —
Tjafcle V.
The f o o d o f brown t r o u t from N o r t h Meadow C re e k (1 9 5 9 ) e x p r e s s e d
a s num ber o f i t e m s p e r s to m a c h and p e r c e n t a g e o c c u r r e n c e .
T otal f i s h ..........
June 23
J u ly 14
J u ly 24
Aug. 10
. 20
20
20
20
S e p t. 4
S e p t. 22
20
20
Range in t o t a l
le n g th ( i n c h e s ) .
I . 1 - 2 .9
I . 1 - 2 .5
I . 6 -2 .6
2 . 1 - 3 .1
2 ,0 -3 .7
2 .4 -4 .I
Average le n g th
(in ch es) . . . . . . .
1. 5
1. 7
2.1
2.4
3.1
3.0
Item
Aquatic
Nemata .................. ..
O lig o c h a e ta .........
O stracoda ..............
Isopoda . . . . . . . . .
Amphipoda ........... •.
Ephemeroptera
H ep tag en iid ae . .
S ip h lo n u rid a e . .
B ae tid a e . . . . . . .
E phem erellid ae .
T r ic o r y th id a e . .
P le c o p te ra
Nemouridae . . . . .
C o le o p tera
H y d ro p h ilid ae . .
Elmidss oooosooo
C u rc u lio n id a e . .
T r ic h o p te ra
Psychomiidae . . .
Hydropsychidae .
H y d ro p tilid a e . .
Lim nephilidae . .
B ra c h y c e n trid a e .
m isc. T rich o p . .D ip te ra
T ip u lid a e ...........
Psychodidae . . . .
P ix id a e . . . . . . . .
Jh
0)
-Q
I
S
<D
CD
-P
Ui
CD
O
S.
IX
<D
CD
-P
-P
CD___ CD
S
O
h
0)
Ph
CD
CD
-P
0)____ CD
§
S
8
Oh
I
S.
0.05
T5
0 .05
55
0 .10
10
<p
<D
CD
-P
CU
CD
CD
-P
CD
CD
I
S
§
Oh
I
S
8
Oh.
0 .3 0
30
8
Oh
0.10 10
0.25 10
0.05
0.0 5
5
0.25
0.2 0
0.85
0.55
20
15
60
20
0 .2 0 15
0.10 10
0.15
0 .0 5
0 .1 0 10
5 0.0 5 5
10
0.50
40
0.95
0 .2 0
40
10
0.5 0
30
3 .0 0
0.15
0 .10
85 1.15 60
15
IO 0.75 45
0.05
5
0 .1 0
10
0.25
15
0 .2 0
20 0.15 .15
0.05
5
0.05
5
10
0.05
0.05
5
5
1.6 0
0 .10
50
10
0.05
0 .4 0
4.1 5
0.3 5
5
15
65
30
0.1 0
0 .30
1.95
0.35
0.15.
15
0.45
30
0.5 0
0.15
15
0.5 0
30
0 .7 0
0-20.
10
0 .1 5
0 .1 0 10
5
0.75
0.25
0.10
20
20
10
-
0.15 15
0 .20
10
30 0 .2 0
30 1.75
25 0.45
0.15
45 0.10
20
75
25
5
10
35 0.30 20
0 .5 0 15
15. 0.3 0 15
-22-
Table V ( c o n t in u e d ) .
June S23
J u ly 14
CU
Item
F
0h)
S
C
CU'
X)
§
S
g.
O..
A
CU
-Q •
S
CTi
' CTi
-P
to
C
CU
A
CD
CU
CD
t
S
C
CU
A
CU
CU
Li
C
CU
CU
IS
A
CU.
CU.
A
CU
§
S
-P
Q
CU
22
CD '
CD
CU
CD
-P
-P
Sept
S e p t. 4
CU
CD
CU
CD
CD
Aug. 10
J u l y 24
/-P
A
CU
-Q
CT
CU
%
a
CU
o
S
CU
D ip te ra c o n t. . .
S im u liid a e . . . .
0.05 -.5 0.30 15 0.25 15 1.05 55 I . 70 60 0.0 5 5
11.90' 95 32.25 IOQ 16.40 100 10.55 100 18.10 100 8.1 0 80
Tendipedidae . .
0.15 15
H eleidae ...........
0.25 15'
0.15 10
S tra tio m y id a e .
5 0 .2 0 15 0 .1 0 10
0.15
5 0.05
Musidae . . . . . . .
0.15 15
m isc. D ip te ra .■ 0.95 45 2 .3 5 55 3.6 5 95 2.85 60 7 .6 5 80 2 .2 0 60
A cari ....................
0.50 20 0.30 10 0.35 15 0.25 10 0 .70 15 0 .3 5 20
0.10 5
0.10
5
Gastropoda .........
0.30 10
f i s h eggs .........
"
10
5
5
5
p la n t m a te ria l .
0.1 0 10
u n i d e n t i f i e d ...
T e rre stria l
Homoptera
A phididae .........
C ic a d e llid a e ..
Hymenoptera
Formicidae . . . .
T o ta l
•
0.05
0.05
■16.75
5
5
0,25
0.05
37.20
10
5
4 .6 0
60
0 .3 0
0.15
20
10
0 .2 0
0 .05
1,10
10
0.05
5
0 .05
3 0 .5 0
22.30
3 6 .4 0
20 2 .2 0 5cr
5
5
.9 .7 0
-2 3 T a b l e V I.
The f o o d o f brown t r o u t i n t h e M adison R i v e r (1 9 5 9 ) e x p r e s s e d
a s num ber o f i t e m s p e r s to m a c h a n d p e r c e n t a g e o c c u r r e n c e .
T o ta l f i s h .............
Range in t o t a l
le n g th ( in c h e s ) .
Average le n g th
( in c h e s ) ................
June 23
20
Ju ly 9
20
1 . 3-:2.4
I . 4 -2 .3
I . 5 - 2 .7
1 .0
1 .7
1.9
2 .2
M
<u
I
s
A q u a tic '
C ladocera ........... ....
Copepoda ..................
Ephemerbptera
H ep tag en iid ae . . .
B a e tid a e ................
raise. Ephem. . . . .
Hemiptera
C o rix id a e .............
T ric h o p te ra
Hydropsychid^e
H y d ro p tilid a e . . .
L im nephilidae . . .
D ip te ra
S i m u l i i d a e ......... .
Tendipedidae . . . .
raise. D ip te ra . . .
Gastropoda ..............
u n i d e n t i f i e d .........
S
a,.
0 .4 5 20
3 .7 0 35
2 .3 0 60
8 .2 5 75
T e rre stria l
Homoptera
Aphididae .............
C ic a d e l l i d a e . . . .
Hymenoptera
Fbrm icidae . . . . . .
raise: Hymenop. . .
T otal
cn
-p
C
. cu
0)
CD
CD
CD
-P
N
C
OJ_________ CD
-P
A
C
CD_______ CD
M
0)
a,
H3
s
“
CD
a.
31.70 85
12.25 40
0.08
0.25
8
17
0.05 5
0.15 10
0 .17
0.25
0.33
17
17
8
0.05
0.08
8
I
S'
5
0.85 35
1.80 30
0.2 0
0.05
14.90
Cn
-P
C
47.10
7.0 8 100
24.08 100
5
5
3 2 .3 2
§
S
2 .5 -3 .7
.
CD
CU
CD
Aug. 24
15
Aug. 10
12
0 .9 -1 .2
CD
Item
J u l y 25
.12
3.1
CD
CD
-P
CD
%
Ph
S
S
C
CD
H
CD
Ph
5 4 .0 0 100
1.25 50
5 .7 5
83
0 .3 3
4 .1 7
3 .6 6
0 .33
0 .1 7
25
83
40
17
17
0.0 8
8
69.74
33.80 100
1.67
1.27
0.67
67
53
27
4.53
5.8 0
1.60
0.20
0.20
80
87;
33
7
20
0.13
7
0.20
0.13
13
13
50.20
-2 4 -
c o l l e c t i o n s , com prising 25 and 26 p e r c e n t of th e t o t a l , r e s p e c t i v e l y , how­
e v er i t was found in only a few f i s h .
As in the case of rainbow t r o u t ,
b o th G ladocera and Copepoda were a b seltt from th e August 24 c o l l e c t i o n ,
which was p ro cu red downstream from a l a n d s l i d e t h a t dammed the r i v e r .
M isc e lla n eo u s D ip te ra were th e most predom inant food item s in the June 23
and J u l y 25 c o l l e c t i o n s and were n e x t to C ladocera and Copepoda in abund­
ance in th e J u l y 9 c o l l e c t i o n .
The numbers o f m is c e lla n e o u s D ip te ra p e r
stomach ranged from 38 to 75 p e r c e n t of th e t o t a l in th e l a t t e r th re e
c o l l e c t i o n s , and were follow ed in abundance by Tendipedidae la r v a e w ith
2-22 p e r c e n t o f th e t o t a l in the same c o l l e c t i o n s .
In th e August 10 c o l ­
l e c t i o n , Tendipedidae la r v a e were n e x t in abundance to C la d o c e ra , when
th ey c o n s t i t u t e d 6 p e r c e n t of the to ta ^ number of organism s p e r stomach,
follow ed by m is c e lla n e o u s D ip te ra w ith 5 p e r c e n t .
predom inant food in the August 24 c o l l e c t i o n .
B a e tid a e was the most
I t was p r e s e n t in a l l the
stomachs in t h a t c o l l e c t i o n and th e number of th e se organism s p e r stomach
c o n s t i t u t e d 67 p e r c e n t of the t o t a l .
B a e tid a e was follow ed in abundance
by T e n d ip e d id a e , S im u lid a e , H ydropsychidae,• m is c e lla n e o u s D i p t e r a , and
H y d ro p tilid a e r e s p e c t i v e l y in t h a t c o l l e c t i o n .
South Fork of the Madison R iver (Table V I I ).
Tendipedidae la rv a e
were th e most predom inant food organisms in th e J u ly 11 and September I
c o lle c tio n s.
They appeared in a l l c o l l e c t i o n s from t h i s l o c a t i o n .
The
numbers o f th e se item s p e r stomach d e c re a se d from 59 p e r c e n t of the ^tOtiaI
on June 23 to 13 p e r c e n t on August 10, and in c re a s e d to 42 p e r c e n t on
September I .
They o c cu rred in 58-95 p e r c e n t of th e stomachs.
B aetidae
was p r e s e n t in a l l c o l l e c t i o n s from t h i i s t a t i o n and i t s numbers p er
-25Ja b le V II.
Th^ f o o d o f brown t r o u t i n t h e S o u th F ork o f t h e M adison R i v e r
( 1 9 5 9 ) e x p r e s s e d a s num ber o f i t e m s p e r . s t o m a c h and p e r c e n t a g e
occurrence.
June 23
T o ta l f i s h ...........
Range in t o t a l
le n g th ( i n c h e s ) .
20
I .
Average le n g th
( in c h e s ) .............
Item
I
0
CD
(0
4-)
C
0
20
.
I . 8 - 2 .8
I . 7 -3 .6
1 .8
2 .0
2 .3
2 .6
"
M
0
0
CD
(0
4->
C
0
I
0.25
Oi 05
0.25
3 .0 5
0.10
0.75
15
95
10
50
0.45 25
1.30 40
1.05 30
0.45
5
5
5
0.05 5
0.10 10
5
S e p t. I
12
20
0 .10 10
0,10 5
0.05 5
0.05
■
I . 5 - 2 .7
I
i
Aug. 10
I . 2 - 2 .5
. 1.5
A
J u l y 25
2 0
1 -2 .I
0)
A quatic
H iru d in ia .............
C ladocera .............
O stracoda ..............
Copepoda ................
Amphipoda .............
Ephemeroptera
S ip h lo n u rid a e ; .
B ae tid a e .............
L e p to p h le b iid a e .
E phem erellid ae .
P le c o p te r a •
Nemouridae . . . . .
C o le o p tera
H a lip lid a e . . . . . .
D y tis c id a e .........
T r ic h o p te ra
G loss olseiha t i d a e .
H y d ro p tilid a e . .
L im n ep h ilid ae . .
raise. T richop. .
D ip te ra .
T ip u lid a e . . . . . .
S im u liid a e .........
Tendipedidae . . .
H eleidae . . . . . . .
raise. D ip te ra . .
A cari .......................
J u l y 11
0.05
0.05
5
5
&
f-i
0
§
S
CO
4->
C
0
§
a,
0.30 10
1 .10 25
0.05 5
OJfcv' 15
0.20 15
0
CD
:
A
0
0
-Q
0
O
S
S
S
P.
I
9.0 8 25
0
CD
0
4->
C
0
I
-0.05 5
0.45 25
0.05 5
0.0 8 8
0.1 7 17
0.70 35
0.35 30
2.6 5 65
0.25 17
1.08 50
0.05 5
1.35 65
0.70 25
0.25 17
. 0.-15 15
0.05
5
0.05
0.05
5
5
0.10
5
0.25 20
0.25 17
0.05
0.0 8
8
0; 08
0,08
8
8
5
0.10 5
1.40 35
1.85 60
0.20 15
0.2 0 15
7 .5 0 95
0.05 5
0.05 5
3 .5 0 75
0.05 5
0.85 45
1.20 60
0.10 10
0.50 20
0.08 8
1.83 58
0.1 7 17 .
5;50 70
0.40 30
0 .4 0 25
-26-
Table VII ( c o n tin u e d ) .
T e rre stria l
Homoptera
C ic a d e llid a e . . . .
T o tal
0.05. 5
0 .20 15
.
.
12.70
7.8 0
0 .1 7 17
7.65
Percen tag e
Number
0 .10 10
S e p t . ■I
Percen tag e
5
Aug. 10
Number
Number
0.0 5
P ercentage
P ercen tag e
J u l y 25
Number
A q u a tic," fcpnt.
T eleo stei
C o ttid a e ................
■ u n i d e n t i f i e d .........
J u l y 11
Percen tag e
Item
Number
June 23
13.65
13.20
V
'
-27-
stomach ranged from 8 to 35 p e r c e n t of th e t o t a l .
I t was th e most p r e ­
dominant food in th e J u l y 25 c o l l e c t i o n .
This item o ccu rred in 40-95 p e r ­
c e n t of th e stomachs from t h i s s ta tio n ,.
C ladocera was th e most predom inant
food in th e August 10 c o l l e c t i o n , where i t c o n s t i t u t e d 66 p e r c e n t of the
t o t a l number of item s p e r stomach.
I t was a l s o p r e s e n t in th e J u ly 25
c o l l e c t i o n w ith 14 p e r c e n t .
I t o ccu rred in only f iv e of th e 20 stomachs
on each of th e se two d a t e s .
Other organisms c o n s t i t u t i n g over 10 p e r c e n t
o f the t o t a l number of item s p e r stomach on one or more d a t e s w ere:
EphemerelI i d a e , H y d r o p tilid a e , and L im n ep h ilid ae.
Duck Creek (Table V I I I ) .
Stomachs from c o l l e c t i o n s taken on June 23,
J u l y 9 , and September I c o n ta in e d p re d o m in a n tly Tendipedidae la r v a e .
numbers p e r stomach c o n s t i t u t e d from 30 to 59 p e r c e n t of th e t o t a l .
The
Mis­
c e lla n e o u s D ip te ra were p r e s e n t in a l l c o l l e c t i o n s and were th e most p r e ­
dominant food item s in the J u l y 25 c o l l e c t i o n .
T h eir numbers p e r stomach
ranged from 6 to 36 p e r c e n t of the t o t a l and they o ccu rred in 31-70 p e r c e n t
o f the stom achs.
C ladocera c o n s t i t u t e d 22 p e r c e n t of th e t o t a l number of
item s p e r stomach on J u l y 2 5 , b u t o c cu rred in only one of the n in e f i s h in
th a t c o lle c tio n .
B a e tid a e was p r e s e n t in a l l c o l l e c t i o n s and th e number
p e r stomach ranged from 10 to 32 p e r c e n t of the t o t a l .
I t o ccu rred in
38-70 p e r c e n t of th e stomachs.
The only in s ta n c e where small t r o u t stomachs c o n tain ed a r e l a t i v e l y
l a r g e number of f i s h was th e J u ly 9 c o l l e c t i o n from Duck Creek.
Seven of
th e 20 brown t r o u t stomachs in t h i s c o l l e c t i o n co n tain ed sm all s c u lp in s
( C o ttu s b a i r d i ) . which were ap p ro x im a te ly 8 m i l l i m e t e r s in le n g th .
r
-28T able V I I I .
The f o o d o f brown t r o u t i n Duck C re e k (1 9 5 9 ) e x p r e s s e d a s
num ber o f i t e m s p e r s to m a c h a n d p e r c e n t a g e o c c u r r e n c e .
June 23
Ju ly 9
20
T o ta l f i s h ...........
J u l y 25
20
S e p t. I
16
9
Range in t o t a l
le n g th ( i n c h e s ) .
I . 1 -2 .0
I . 2 - 2 .2
I . 6 -2 .2
2 .1 -3 .3
Average le n g th
( in c h e s ) .............
1 .5
1 .6
1.9
2 .8
Item
A
CD
I
Z
A quatic
O lig o c h ae ta .........
C ladocera .............
O stracoda . . . . . . .
Copepoda ................
Amphipoda .............
Ephemeroptera
S ip h lo n u rid a e . .
B ae tid a e .............
E phem erellid ae .
P le c o p te ra
Nemouridae .........
Hemiptera
C o rix id a e . . . . . .
C o le o p tera
H a lip lid a e .........
D y tis c id a e .........
T r ic h o p te ra
H y d ro p tilid a e . .
L im ep h ilid ae ..=
m isc. T rich o p . .
D ip te ra
Tendipedidae . . .
m isc , D ip te ra . .
T e le o stei .
C o ttid a e ..............
T e rrestria l
Homoptera
Aphididae . . . . . .
T o tal
0.4 0
0 .1 0
• 2 .9 0
0 .3 5
-P
C
CD
S
Ph
10■
10
70
20
CD
CD
CD
Q).
Cn
U)
A
-P
A
S
Ph.
I
S
S
Ph
1.33
0.33
11
11
0.11
11
0.78
0.11
56
11
CD_______CD
I
S
0.0 5 5
0.0 5 5
0 .3 0 15
0 .3 0 20
0.0 5 5
0 .3 0 20
3 .7 5 70
0.0 5
-P
C
C
CD__________CD
CD
CD
A
CD
I
S
0 .0 6
C
CD
S
Ph
6
0.75 38
0 .0 6
5
-P
6
1.5 6 69
0.05
OilO
5
22
0.38 25
0.0 5
5
0.0 5 5
0 .60 10
6 .70
0 .8 0
85
40
3 .8 0 80
1 .50 70'0 .7 0 35
11.40
0 .56
5
0.1 0
11.65
5 .
0 .88 31
0.81 44
0 ,0 6 6
0 .22 .22
2 .2 2 .66
2 .1 9 50
0 .4 4 31
11
0 .0 6
0.33., 22
r' 6.10
7.25
.0 .1 1
6
„
-2 9 -
Brook Trout
T rout Creek (Table IX).
Tendapedidae la r v a e were abundant food item s
in a l l brook t r o u t c o l l e c t i o n s and were th e most predom inant organisms in
stomachs from th e June 4 , J u l y 21 and August 18 c o l l e c t i o n s .
The number
o f organisms p e r stomach ranged from 20 to 48 p e rc e n t o f the t o t a l and
th e s e organisms o c cu rred in 70-95 p e r c e n t of the stomachs in a l l c o ir
le c tio n s.
B ae tid a e was a l s o abundant and was the mbst predom inant food in
th e June 30 and August 15 c o l l e c t i o n s .
The number of th e s e organisms p e r
stoma,ch ranged from 11 to 45 p e r c e n t o f the t o t a l and t h i s item occurred
in 75-IOO p e r c e n t o f th e stomachs.
Copepoda was the most abundant food
organism ^aken in th e A p ril 22 c o l l e c t i o n , where i t in c lu d e d 39 p e rc e n t of
th e' tdta], number o f item s p e r stomach.
in t h i s c o l l e c t i o n .
C ladocera c o n s t i t u t e d 18 p e rc e n t
H y d ro p tilid a e o c cu rred in a l l c o l l e c t i o n s except
th o se taken on A p ril 22 and June 4 , and ranged from 2 to 6 p e r c e n t of the
t o t a l number of organisms p e r stomach in the v a rio u s c o l l e c t i o n s .
p e rc e n ta g e in c r e a s e d as th e season p r o g r e s s e d .
The
S im u liid a e o ccu rred in
th e s e same c o l l e c t i o n s and c o n s t i t u t e d 2-10 p e rc e n t of th e to ta l.n u m b e r
of organisms p e r stomach.
th e season p ro g r s s e d .
The p e rc e n ta g e of t h i s item a l s o in c re a s e d as
Aphididae was abundant in the c o l l e c t i o n s taken on
August 5 and August 18 b u t no reaso n f o r t h e i r p resen ce was e v id e n t.
D iscu ssio n
Although foods from th e d i f f e r e n t stream s v a rie d c o n s id e r a b ly , Tenddp ed id ae la r v a e were abundant in a l l rainbow t r o u t c o l l e c t i o n s and'made up
40 p e r c e n t of the t o t a l number of organisms p e r stomach.
The rem aining 60
141122
•“ 3 D "
The f o o d o f s m a l l b ro o k t r o u t i n T r o u t C re e k (1 9 5 9 ) e x p r e s s e d a s
num ber o f i t e m s p e r s to m a c h an d p e r c e n t a g e o c c u r r e n c e .
20
20
20
20
20
I . 1 -2 .I
I . 3 - 2 .4
2 .2 -3 .3
2 .6 -3 .7
3 .0 -4 .0
1.7
1 .9
2 .7
3.1
3 .5
Range in t o t a l '
le n g th ( in c h e s ) . 0 . 9 - 1 . 4
Average le n g th
( in c h e s ) .............
1.1
A quatic
Nemata ....................
H iru d in ia ...........
C ladocera ..............
O stracoda .............
Copepoda ................
Ephemeroptera
H e p tag en iid ae . .
B a e tid a e ..............
P le c o p te ra
Nemouridae . . . . .
C o le o p tera
H a lip lid a e .........
D y tis c id a e . . . . .
H ydrophylidae . .
C u rc u lio n id a e . .
TrTchoptera
H y d ro p tilid a e . .
L im n ep h ilid ae . .
D ip te ra
T ip u lid a e ...........
Sim ulidae .........
Tendipedidae . . .
H eleid ae .............
S tr a tio m y id a e . .
R hagionidae
Musidae ................
m isc. D ip te ra . .
0.25
Percen tag e
Number
P ercentage
Number
■
I
M
rh
I
I
0 .1 0
I
2 .6 9 31
0.13 13
5 .6 9 56
5
0 .05
5
0 .0 5
5
0.4 0 ..35
0.15 1'0
0.15 10
1.69 75' ■1.75 80
0.1 5 15
2 .4 0 75
0 .0 6
0.05
6
0 .10 10
Percen tag e
16
T o ta l f i s h . . . . . .
Number
Aug. 18
P ercentage
Aug. 5
Number
J u ly 21
P ercen tag e
June 30
Number
June 4
P ercentage
Apr. 22
Number
T a b l e IX.
0.05
5
2 .8 8 81
1.13 44
2 .4 0 90
0 .15 10
0.19 19
0..45 30
4 .2 5 85
5
0 .25 25
7 .95 100
0.1-0 . 10
9.20 100
0:80
40
0.3 0
20
0 .0 5
5
0.10
0.10
0.35
0 .40
10
10
15
20
0.0 5
5
0.15 15
0 .25
15
0 .1 0
5
0.75 50
1.9 0
55
2 .3 0
0.15
75
15
1 .05
7 .2 0
0 .3 5
0 .05
0 .1 5
0 .1 0
0 .4 0
50
95
25
5
10
10
15
3 .9 0
11.05
0 .4 0
0 .3 0
0.1 0
0.35
0.15
45
95
20
25
10
25
25
0 .1 0 10
1.95 70
0 .3 5 30
0..05 5
0.35
0.7 0
6.40
0.15
25
35
85
15
0 .2 0 15
Table IX (.continued)
A pr.
22
June 4
Item
CU
S
CU
A
CU
Oh
0 .0 6
6
-Q
A c a r i ■.............................
G astrop od a . . . . . .
f i s h ................................
p la n t m a te r ia l
CU
CU
A
C
I
O
I
C
I
2
CU
CL
T o tal
CU
S
A
CU
PU.
CU
A
J u l y 21
K
S
§
2
S
CL
5
20
0 .0 5
5
Aug.
30
5
10
0 .1 5
10
Aug.
CU
I
2
A
CU
CL,
A
1 .9 0
0 .3 5
55
5
18
CU'
CU
A,
C
CU
CU
2
A
CU
CL,
1 .5 0
55
0.2 5
20
0 .1 0
10
4 .7 0
\8 0
0.2 5
0 .7 0
10
5
0 .6 0
25
5
5
0 .1 0
5
CU
CU
e:
CU
CU
CU
0 .7 0
0 .0 5
6
T e r r e s tr ia l
O rth o p tera
L o c u s t i d a e ............
H om op tera
A p h i d i d a e ...............
C ic a d e llid a e . . .
F u l g o r i d a e ............
H ym en op tera
F o r m ic id a e . . . . .
A r a n e id a
T h o m i s i d a e ............
30
CU
CU
CD
CJ)
CU
C
June
3 .3 5
0 .0 5
75
•5
I
14.77
5 .0 0
5 .3 0
0 .0 5
5
0 .1 5
10
0 .0 5
5
0 .0 5
5
14.15
.2 6 .4 5
37.90
-32-
p e r c e n t was d iv id e d ab o u t e q u a lly among m is c e lla n e o u s D i p t e r a , B a e tid a e ,'
Copepoda, C ladocera and m is c e lla n e o u s food.
As th e season p ro g re s se d and
f i s h c o n se q u e n tly grew l a r g e r , th e r e was a g r e a t e r v a r i e t y of organisms in
th e stomachs.
I d y l l (1942) s tu d ie d th e food of 15 rainbow t r o u t and 20
c u t t h r o a t t r o u t , up to 4 in c h e s in t o t a l l e n g t h , from th e Cowichan R iyer
System in B r i t i s h Columbia.
He found Tendipedidae was th e predominant
food o f b o th f i s h , c o n s t i t u t i n g 7.6 p e r c e n t and 64 p e r c e n t o f the t o t a l
number o f item s p e r stomach, r e s p e c t i v e l y .
He found P le c o p te r a was second
in im portance in rainbow t r o u t (12 p e r c e n t ) and Ephemeroptera in c u t t h r o a t
t r o u t (16 p e r c e n t ) .
Hazzard and Madsen (1933) determ ined th e food of 48
c u t t h r o a t t r o u t ( I . 0 - 1 .6 in c h es in t o t a l le n g th ) from a t r i b u t a r y of
Jackson Lake, Wyoming.
They r e p o r te d Tendipedidae la r v a e to be the p r e ­
dominant food, making up 20 p e r c e n t o f the t o t a l number o f organisms p e r
stomach, w h ile Copepoda and D ip te ra pupae and a d u l t s were p r e s e n t in la r g e
numbers.
A c a r i , O lig o ch aeta and Ostracoda were a l s o q u i t e numerous.
These l a t t e r o c cu rred in th e rainbow t r o u t o f the p r e s e n t stu d y bu t we^e
of minor im p o rtan ce.
Te'ndipedidae la r v a e c o n tr ib u te d 32 p e r c e n t of the t o t a l number of
organisms p e r stomach in brown t r o u t ( F ig u re l ) w ith m is c e lla n e o u s D i p t e r a ,
B a e tid a e , and m is c e lla n e o u s foods each w ith about equal amounts.
The
number of C ladocera p e r stomach in brown t r o u t in c lu d e d 21 p e r c e n t of th e
t o t a l , w hile Copepoda in c lu d e d only 4 p e r c e n t .
I d y l l (1942) examined :
stomachs of 35 brown t r o u t , up to 4 in c h e s in t o t a l le n g th and found t h a t
Tendipedidae c o n s t i t u t e d about 70 p e r c e n t of th e t o t a l number o f organisms
p e r Stomach, follow ed by Ephemeroptera w ith 15 p e r c e n t .
Clemens (1928)
Rainbow T rout
T otal f i s h - 356
C ladocera
Tendipedidae
40%
Copepoda
Average le n g th - 1.5 in c h es
Average number of organisms
p e r stomach - 27
- yB a e tid a e / m isc.
X 12%
/ D ip tera
/
13%
m isc.
15%
Brown T rout
T otal f i s h - 356
C ladocera
Tendipedidae
^
32%
Average le n g th - 2.1 in c h es
Average number of organisms
p e r stomach - 23
D ip te ra
, 14%
Copepoda
4%
B ae tid a e
m isc.
14%
Brook Trout
Copepoda
Total f i s h - 116
Acari-*->
4%
H y d ro p tilid a e
Tendipedidae
\
31%
Average le n g th - 2 .3 in c h e s
Average number of organisms
p e r stomach - 17
S im u liid a e
B ae tid a e
Aphididae
8%
F ig u re I .
P e rc e n ta g e s of th e t o t a l number of item s found in the stomachs
of rainbow t r o u t , brown t r o u t and brook t r o u t f r y and f i n g e r l i n g s .
i-34-~
s tu d ie d th e food of seven brown t r o u t (2 -3 in ch es in t o t a l le n g th ) from
Oneida County, New York apd found the predom inant foods were T ric h o p te ra
and Ephem eroptera.
Although numerous d i f f e r e n c e s o c cu rred between th e foods o f rainbow
t r o u t and brown t r o u t , only fo u r were v ery n o t i c e a b l e .
C on sid erin g a l l
c o l l e c t i o n s ,• C iadocera was l e s s abundant in rainbow t r o u t than in brown
t
t r o u t , w h ile Copepoda was le ss , abundant in th e l a t t e r .
In s e v e ra l c o l­
l e c t i o n s from Duck Creek and the South Fork of the Madison R iv e r, B aetid ae
was more predom inant in brown t r o u t than in rainbow t r o u t , w h ile T endip e d id ae la r v a e were more predom inant in th e l a t t e r .
Changes in d i e t
com position th ro u g h o u t the season were g e n e r a l l y q u ite s i m i l a r in both
s p e c ie s of f i s h .
Although th e most abundant food in sm all brook t r o u t was Tendipedidae
l a r v a e , B a e tid a e was n e a r ly as pred o m in an t.
T o g e th e r, thebe c o n s t i t u t e d
over h a l f th e t o t a l number of organisms p e r stomach.
food was comprised o f :
and Copepoda.
Most of the o th e r
A p h id id a e , S im u liid a e l a r v a e , H y d r o p til id a e , A cari
Clemens (1928) found t h a t Tendipedidae ( l a r v a e and pupae)
were th e predom inant food org an ism s, follow ed by E phem eroptera, in I 55
brook t r o u t up to 4 in c h es in le n g th .
R ick er (1930) a n a ly se d 41 brook
t r o u t ( 0 . 8 - 4 . O in c h e s in t o t a l le n g th ) stomachs from O n ta rio , in which
Tendipedidae made up 39 p e r c e n t of th e t o t a l volume of organisms per
stomach.
He found C la d o c e ra , Copepoda and Ostracoda to be q u i t e im p o rtan t
f o r f i s h 0 . 8 - 1 . O in c h e s lo n g .
R e s u lts from Trout Creek (T able IX) agree
w ith t h i s .
The foods of sm all brook t r o u t were somewhat d i f f e r e n t from those o f
rainbow t r o u t and brown t r o u t .
B a e tid a e comprised a much l a r g e r p o r ti o n
of th e food in stomachs o f brook t r o u t than in the o th e r two s p e c ie s .
C ladocera ,and. m is c e lla n e o u s D iptera'. were l e s s abundant in brook
t r o u t , w hile A p h id id a e , S im u liid a e l a r v a e , H y d ro p tilid a e and Acari were
more abundant.
These d i f f e r e n c e s m ight be e x p la in e d by th e lower e l e v a t i o n
of th e stream and d i f f e r e n c e in h a b i t a t where brook t r o u t were c o l l e c t e d .
As th e season p r o g r e s s e d , and sm all t r o u t grew l a r g e r , t h e i r stomachs
c o n ta in e d a g r e a t e r v a r i e t y o f org an ism s.
Larger t r o u t , no doubt a re a b le
to c a p tu r e and swallow b ig g e r organisms and they range over more o f the
stre a m , where a g r e a t e r v a r i e t y of organisms a r e found.
Summary
1.
Samples of rainbow t r o u t , brown t r o u t and brook t r o u t f r y and
f i n g e r l i n g s were o b ta in e d f o r stomach a n a l y s i s from f i v e southw estern
Montana stre a m s.
2.
C o l l e c t i o n s were secured a t about two-week i n t e r v a l s , from about ■
th e time t r o u t began to feed u n t i l th ey reached a le n g th o f a p p ro x im ately
fo u r in c h e s .
3.
Samples were p ro cu red from A p ril 22 to September 22.
Where numbers p e r m i t t e d , 20 f i s h o f each s p e c i e s , from each
stream f o r each d a te were randomly s e l e c t e d f o r stomach a n a l y s i s .
4.
A t o t a l o f 356 rainbow t r o u t , 356 brown t r o u t and 116 brook t r o u t
were examined.
5.
The most abundant organisms in th e stomachs o f rainbow t r o y t fry
and f i n g e r l i n g s were th e la r v a e o f T en d ip e d id a e, which made up 40 p e r c e n t
o f th e t o t a l number of organisms p e r stomach in t h i s f i s h .
36-
6.
M isc e lla n e o u s D i p t e r a , B a e tid a e , Copepoda, C ladocera and m is c e l­
laneous food were a b o u t e q u a lly abundant in rainbow t r o u t stomachs' and
comprised th e rem aining 60 p e r c e n t o f the d i e t .
7.
Tendipedidae la r v a e c o n s t i t u t e d 32 p e r c e n t o f the t o t a l number of
organisms p e r stomach in sm all brown t r o u t , and was th e predominen£ food.
8.
M isc e lla n eo u s D i p t e r a , B a e tid a e , and m is c e lla n e o u s foods com­
p r i s e d about, equal p o r t i o n s o f brown t r o u t d i e t .
Cladocera exceeded
Copepoda in abundance in th e s e stomachs.
9.
C o n sid e rin g a l l c o l l e c t i o n s , Cladocera was l e s s abundant in
stomachs of rainbow t r o u t than in brown t r o u t , w hile Copepoda was more;
ab undant.
B a e tid a e was more predom inant and Tendipedidae la r v a e were l e s s
predom inant in stomachs of brown t r o u t than in rainbow t r o u t in s e v e ra l
c o lle ctio n s.
10.
Changes in d i e t com position th ro u g h o u t th e season were s i m i l a r
in rainbow t r o u t and in brown t r o u t .
11.
Aphids were abundant in th e stomachs of rainbow t r o u t and brown
t r o u t c o l l e c t e d in N orth Meadow Creek d u rin g and a f t e r r a i n s .
12.
C ladocera and Copepoda were abundant in rainbow t r o u t and brown
t r o u t stomachs c o lle c te d , from the Madison R iver s t a t i o n , a s h o r t d is ta n c e
downstream from Hebgen R e s e rv o ir.
13. ' Tendipedidae la r v a e were th e most abundant food item s in brook
t r o u t stom achs, however B ae tid a e comprised n e a r ly as many organisms p e r
stomach.
14.
Cladocera ; and m is c e lla n e o u s D ip te ra ^ e r e l e s s abundant,
.
in brook t r o u t than in th e o th e r two s p e c i e s , w hile A phididae, S im u liid a e
-3 7 -
l a r v a e , H y d ro p tilid a e and A cari were more abundant.
1 5 / '.As th e seasdn p ro g re s s e d and f i s h became l a r g e r , th e r e was a
g r e a t e r v a r i e t y o f organisms in th e stomachs of a l l t h r e e s p e c ie s of f i s h .
L i t e r a t u r e C ited
Clemens, W. A. 1928. The food o f t r o u t from the stream s o f Oneida County,
New York s t a t e . , T ran s. Am. F i s h e r i e s S o c ., 58s 183-197.
-4
*
,
H azzard, A.; S. and M. J . Madsen. 1933. S tu d ie s of th e food of the c u t­
t h r o a t t r o u t . T ran s. Am. F i s h e r i e s S o c ., 63s 198-203.
H olton, G. D. 1953. A t r o u t p o p u la tio n stu d y in a sm all creek in G a l l a t i n
County, Montana. J o u r . JAIildl. M g t., 18 ( I ) s 62-82.
I d y l l , C. 1942. Food of rainbow , c u t t h r o a t , and brown t r o u t in the
Cowichan R iv er system , B. C. J o u r . F is h . Res. Bd. Canada, 5 (5)s
448-458 .
'' ;
R ic k e r, W. E'. 1930. Feeding h a b i t s o f sp eck led t r o u t in O n ta rio w a te r s .
T r a n s . ■Am. F i s h e r i e s S o c ., 60s 64-72.
MONTANA STATE UNIVERSITY LIBRARIES
3
1
762 100 3770 O
f 946f
t b f ■2
141122