Observations on the fish population of Willow Creek reservoir, Montana
by James A Posewitz
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 A Posewitz (1961)
Abstract:
Observations were made on the spawning, growth,, distribution, harvest and movement of trout in
Willow Creek Reservoir from March through November, 1960. Successful reproduction was observed
only in Willow Creek. Rainbow trout taken in 1960 showed a decline in average size and slower
growth rate than the same species taken in previous years. Distribution of trout in the reservoir
appeared to be correlated with water temperatures, Rainbow trout were most evenly distributed in the
reservoir when water temperatures were warmest, but were concentrated near the surface when water
temperatures were cool, Brown trout were always more abundant near the bottom, and at maximum
temperatures were restricted to deeper areas. Game fish caught by gill nets included 69.05 percent
rainbow trout, 30.04 percent brown trout, 0.68 percent brook trout and 0.23 percent mountain
whitefish. Anglers harvested an estimated 14,868 trout during the 1960 (six week) fishing season. The
catch was composed of 97.27 percent rainbow trout, 2.47 percent brown trout and 0.26 percent brook
trout. Recoveries of marked fish indicated a wide dispersal of fish marked in the tributaries during
spawning, and of those planted in 1960. OBSERVATIONS ON THE FISH POPULATION
OF .WILLOW CREEK RESERVOIR9 MONTANA
by
. JAMES A POSEWITZ
< /‘
A THESIS
Subpiiitted to 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
fo r th e ,degree o f
M aster o f S cien ce in F is h and W ild life Management
at
Mohtana S ta te C o lleg e
Approved*.
C hapm an9 Examining Committee
DeaAs G rad W te^ D iv isio n
Bozemans Montana
M archs 1961
J lE S T W ^ !6 J3 S lA C K
A) 2>7f
The Author
I was born in Sheboygan, W isconsin on March 6 , 1935 and com pleted my
e lem en tary and h igh school e d u ca tio n th e r e . In Septem ber, 1953 I e n te re d
Montana S ta te C o lleg e where I com pleted re q u ire m e n ts fo r a B achelor of
S c ie n ce deg ree in F ish and W ild lif e Management in 1957, For two summers,
I was employed by th e Montana F ish and Game D epartm ent; one as an a s s i s t a n t
to a d i s t r i c t f i s h m anager, and one a s foreman o f a f i s h shocking crew, I
was employed fo r one summer a s p a rty le a d e r fo r a f is h c o lle c tin g crew from
Montana S ta te C o lle g e . In November o f 1957 I e n te re d m i l i t a r y s e rv ic e and
served two y e a rs w ith th e U nited S ta te s Army, 15 months o f which were sp e n t
in Germany. I was m a rrie d to Helen V idal in May, 1958 and we now have two
so n s. In S eptem ber, 1959 I was a cc e p ted as a g ra d u a te s tu d e n t in F ish and
W ild lif e Management a t Montana S ta te C o lle g e . This th e s i s i s subm itted as
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 fo r th e M aster o f S cien ce d egree in
F ish and W ild lif e Management
K f S O lO
2
'4
T able o f C o n te n ts
Page
A b s tra c t „
o
6
I n tr o d u c tio n . .
o
o
0
o
0
o
0
'
(
0
o
0
o
o
o
o
0
0
0
9
o
0
(
r
0
o
0
o
0
o
0
o
0
o
0
o
o
o
0
0
0
3
6
0
0
4
0
O b se rv a tio n s oxi spanning and fr y p ro d u c tio n in t r i b u t a r i e s
Age and grow th . 6
G ill n e ttin g r e s u lts . . ; ^
H arv est
7
.
, . «- a ; <; .
^
o o o o o o o o o o o o d ' d o o t > » o o d o o d o » o
12
14
23
Marked f i s h re c o v e ry . ^ ............................... . . . . & & , . . . .
25
Summary
27
0 0 0 ^ 0 0 0 ^ 0 0 0 4 0 ^ 0 0 0 6 0 0 0 0 « 0 0 9 «
L i t e r a t u r e c ite d . . . o o . . « o . . . . . . . , V o o d o o
I
29
-
3-
AblS tra ct
O b se rv a tio n s were made on th e spaw ning» grow th9 d i s t r i b u t i o n , h a r v e s t
and movement o f t r o u t in, W iilow fCreek R e s e rv o ir from March through Nov­
ember 1960. S u c c e s s fu l re p ro d u c tio n was observed only in Willow. C reek.
Rainbpw t r o u t taken in 1960 showed a d e c lin e in av erag e s iz e and slow er
grow th r a t e than th e same s p e c ie s tak en in p re v io u s y e a r s , O is trib U tip h
o f t r o u t in th e r e s e r v o i r appeared to be c o r r e la te d w ith w ater tem pera­
t u r e s . Rainbow t r o u t were m ost ev en ly d i s t r i b u t e d in th e r e s e r v o i r When
w ater te m p e ra tu re s were w arm est, b u t were c o n c e n tra te d n e a r th e s u rfa c e
when w ater te m p e ra tu re s were c o p l. Brown t r o u t were alw ays more abundant
n e a r th e bottom , and a t maximum te m p e ra tu re s were r e s t r i c t e d to deeper
a r e a s . Game f i s h caught by g i l l n e t s in c lu d e d 69,05 p e rc e n t rainbow
t r o u t , 30.04 p e rc e n t brown t r o u t , 0 .6 8 p e rc e n t brook t r o u t and 0.23 p e r ­
c e n t m ountain w h ite f is h . A nglers h a rv e s te d an e stim a te d 14,868 tr o u t
d u rin g th e I960 ( s ix week) f is h in g s e a so n . The c a tc h was composed of
97.27 p e rc e n t rainbow t r o u t , 2 .4 7 p e rc e n t brown tr o u t and 0 .2 6 p e rc e n t
brook t r o u t . R ec o v e rie s o f marked f i s h in d ic a te d a wide d is p e r s a l o f
f i s h marked in th e t r i b u t a r i e s d u rin g spaw ning, and o f th o se p la n te d in
I9 6 0 .
’
-
4-
In tr b d u c tio n
A la r g e number o f in v e s t ig a ti o n s have been made bn f i s h p o p u la tio n s
o f r e s e r v o i r s b u t few concern co ld w ater fis h o
S tu d ie s on cp ld w ater f is h
p o p u la tio n s in C olorado were made by N elson (1955) and Sharpe (.1958).
The
p r e s e n t in v e s t ig a ti o n was conducted from March through November, 1960.
It
in c lu d e d o b s e rv a tio n s on th e l i f e h i s t o r y , d i s t r i b u t i o n and h a r v e s t o f
rainbow t r o u t ( Salmo o a i r d n e r i ) and brown t r o u t ( SaImo t r u t t a ) in a cpld
w a ter impoundment.
Acknowledgements.
G ra te fu l acknowledgement i s due to D r. C; J . D.
Brown who d ir e c te d th e p r o j e c t and a id e d in th e p r e p a r a tio n o f th e manu­
s c rip t.
Thanks a re due to s e v e ra l members o f th e Montana F is h apd Game
d ep artm en t fo r h e lp in th e f i e l d .
John R= Heaton a s s i s t e d w ith th e age and,
grow th a n a ly s is and Tom Leik gave a d y ice re g a rd in g th e c o l l e c t i o n and
a n a ly s is o f c r e e l d a t a .
Thanks a re a le o due to C h arles Qtiesenbury who
su g g este d and o u tlin e d th e d e sig n fo r th e h a r v e s t e s tim a te .
The Montana
F is h and Game D epartm ent p ro v id e d f in a n c ia l su p p o rt Under th e F e d e ra l .Aid
to F is h R e s to ra tio n Act ( P r o je c t number F -9 -R -9 ).
D e s c rip tio n of A re a » W illow Greek R e s e rv o ir i s formed by an e a r th
f i l l e d dam a th w a rt W illow C reek, a t r i b u t a r y o f th e J e f f e r s o n R iver which
i n tu rn i s one o f th re e prim ary headw ater t r i b u t a r i e s o f th e M isso u ri
R iv e r.
T his impoundment i s lo c a te d 4 m ile s e a s t o f H a rris o n , Madison
C ounty, Montana =
I t was f i l l e d fo r th e f i r s t tim e in 1938=
When f u l l , i t
has a s u rfa c e a re a o f 868 a c r e s , a s to ra g e c a p a c ity o f 17,760 a c re f e e t ,
and a maximum d ep th o f 74 f e e t .
The s p illw a y e le v a tio n i s 4 ,7 3 6 f e e t above
-
sea le v e lo
5-
D uring summer and ^ a r ly autumn o f th e stu d y p e rio d , w a ter le v e ls
in th e impoundment d e c re a se d ab o u t 15 f e e t due to i r r i g a t i o n draw-down» The
r e s e r v o i r i s s i t u a t e d in an open r o l l i n g g ra s s la n d and has a d ra in a g e a re a
o f a p p ro x im a te ly 160 sq u are m ile s lo c a te d on th e e a s t s lo p e s o f t ^ e To­
bacco Ropt M ountains*
The -^ trib u ta rie s which e n te r th e r e s e r v o i r a r e :
W illow Creek w ith a d ra ip a g e a re a o f 88*4 sq u are m ile s and an a v erag e flow
o f 43 *I Caf-Sd^ Norwegian Greek w ith a d ra in a g e a re a Of 34*6 sq u are m ile s
and an av erag e flow o f 7*5 c , f ,S a ; and Dry R ollow C reek which i s a v ery
sm all i n t e r m i t t e n t stream *
- The w afer i n th e r e s e r v o i r i s r e l a t i v e l y - c l e a r , even d u rin g ru n -o ff*
in th e stu d y p e r io d , w afer te m p e ra tu re s ranged from 78° (J u ly 22) to 32° FV
( ip e c o y e r, December through March)*
The g r e a t e s t d a ily v a r i a t i o n Occurred
on J u ly 22 w ith a maximum o f 78° arid a minimum o f 63° F»
No marked therm al
s t r a t i f i c a t i o n was observed*
Chemical a n a ly s e s o f w ater from th e impoundment showed th e fo llo w in g si
p h e n o lp h .th a lein a l k a l i n i t y 13 p*p,m*; m ethyl orange a l k a l i n i t y 127 p ,p * m .|
pH 7*3,
Chemical a n a ly s e s o f w ater from fh e two m ajor t r i b u t a r y stream s .
(T able I ) were made by th e Montana S ta te Board o f H ealth*
Rboted a q u a tic v e g e ta tio n was p r e s e n t in a re a s of th e r e s e r v o i r With
d e p th s' l e s s th an 10 f e e t b u t mUch o f t h i s a re a was exposed by draw-down*
F is h observed i n th e r e s e r v o i r were rainbow t r o u t , brown t r o u t , brook
t r o u t (S a lv e IinU s f o n t i n a l i s ) , m ountain w h ite f is h
,• and m o ttle d s c u lp in (-C o ttu s
—
T able I „
6—
Chemical d a ta fo r W illow and Norwegian C reek s, 1960.
Chemical a n a ly s e s
W illow Creek
p 0p 0m0
Norwegian Creek
p 0p oin 0
Iro n (Fe)
Calcium (Ca)
Magnesium
Sodium and P otassium C a lc . (Na-K)
C arbonate r a d ic a l (COg)
B ic a rb o n a te r a d ic a l (HCOg)
S u lp h a te r a d ic a l (SO4)
C h lo rid e (C l)
F lu o rin e (F)
N itr a te s (NO3)
Hydroxide (OH)
1.0
0.9
5 6 .0
2 7 .0
2 5 .0
0 .0
2 9 3 .0
4 9 .0
8 .0
0 .4
0.1
0 .0
5 2 .0
3 7 .0
2 1 .0
0 .0
3 17.0
2 7 .0
2 8 .0
0 .5
0 .0
0 .0
T o tal h a rd n e ss (a s CaCOg)
T o tal d is s o lv e d s o lid s
250
370
281
385
b a ird i).
d ra in a g e .
With th e e x c e o tio n o f th e f i r s t th r e e , a l l a re n a tiv e to the
No re c o rd s were found re g a rd in g th e o r ig in a l in tr o d u c tio n of
t r o u t in to th e r e s e r v o i r b u t sto c k in g re c o rd s sin c e 1953 a re a v a ila b le
(T able 2 ) .
Table 2 .
Year
1953
1954
1954
1955
1957
1958
1959
1959
1960
1960
W illow Creek R e se rv o ir rainbow t r o u t sto c k in g re c o rd s .
S iz e in
in c h es
6-9
I
6-9
3
3
3
6-9
6-9
6-9
6-9
Number
2 ,7 0 0
113,175
2 ,5 9 9
85,966
46,124
58,144
29,988
25,083
29,976
25,000
T o ta l w eight
in pounds
360
85
769
490
708
705
9,630
4 ,8 1 0
7,847
5 ,0 0 0
-7
Rainbow t r o u t have produced spawning ru n s in th e t r i b u t a r y stream s and
a tr a p in W illow Creek has been o p e ra te d s in c e 1950 fo r th e purpose of ob­
ta in in g eggs o f t h i s s p e c ie s (T able 3 ) .
T able 3 .
Data from th e W illow Creek egg ta k in g o p e ra tio n .
Number o f fem ales s trip p e d
Year
Number o f eggs taken
I I iM I ■ Il ■
1950
— —— —
1951
———
1952
— —— —
1953
—
—
1954
1830
1955
1956
1139
1771
1957
988
1958
335
1959*
1960
239
* In 1959 an a d d itio n a l 443 fem ales and 935,088 eggs were
Norwegian C reek.
1 ,2 8 9 ,6 8 0
2 ,2 6 7 ,1 3 6
1 ,7 4 6 ,8 1 0
3 ,5 8 5 ,6 0 0
2 ,6 4 2 ,1 6 4
2 ,4 3 2 ,9 6 0
3 ,6 1 5 ,7 4 4
2 ,4 9 3 ,1 0 2
1 ,773,552
629,748
279,800
tak en from
O b se rv a tio n s on Spawning and
Fry P ro d u ctio n in T r ib u ta r ie s
The t r i b u t a r y stream s p ro v id e spawning a re a s fo r most f is h e s in the
re s e rv o ir.
Spawning f i s h in Norwegian and Dry Hollow C reeks ware c o lle c te d
by e l e c t r o f i s h i n g , u sin g a 220 v o l t D.C. g e n e r a to r .
A s e c tio n o f 300 f e e t
was e s ta b lis h e d in each stream and p r a c t i c a l l y a l l a d u lt f i s h were c ap tu red
in th e s e a re a s on each c o lle c tio n d a te .
The spawning f i s h in Willow Creek
were taken in a tr a p which blocked th e e n t i r e stre am .
T his tr a p was in ­
s t a l l e d p re v io u s to t h i s s tu d y , by th e Montana F ish and Game Departm ent fo r
th e purpose o f o b ta in in g rainbow t r o u t eg g s.
The t r i b u t a r i e s were f i r s t v i s i t e d on March 27 and a t t h a t tim e a d u lt
-
8-
rainbow t r o u t , presum ably from th e r e s e r v o i r , were observed in Norwegian
and Dry Hollow C reek s, no f i s h were seen in W illow C reek 0 Seven samples
were tak en on Norwegian Creek as follow s*
A p ril I , 4 , 8 , 11, and May 7 ,
two on March 30, and one each on
A t o t a l o f 207 male and 124 fem ale rainbow
t r o u t was c o lle c te d (T able 4 ) 0
Four sam ples were tak en on Dry Hollow
C reek; one each on A p ril I , 8 , 11, and May 7 .
A t o t a l o f 71 m ale and 31
fem ale rainbow t r o u t was c o lle c te d (T ab le 4 ) .
T able 4 .
Number, a v erag e le n g th , and av erag e w eight o f rainbow t r o u t
taken e l e c t r o f i s h i n g in Norwegian and Dry Hollow C reek s, I960,
Date
March 30
March 30
A p ril I
A p ril 4
A p ril 8
A p ril 11
May
7
T o ta l number
Average le n g th
Average w eight
Norwegian Creek
Females
M ales
22
25
33
37
29
16
45
207
13,48
0,98
10
21
13
45
7
11
17
124
16,80
1,62
Dry Hollow Creek
Females
Males
——
——
15
——
26
17
13
71
13,18
0,81
“
4
—
13
7
7
31
14,84
1,1 0
The tr a p on W illow Creek was p u t in to o p e ra tio n on March 2 9 , and th e
f i r s t rainbow t r o u t was c ap tu red alo n g w ith seven su ck e rs on A p ril I ,
The
f i r s t eggs were ta k en on A p ril 13, and spaw n-taking c o n tin u e d a t ir r e g u la r
i n t e r v a l s th ro u g h May 8 ,
D uring t h i s p e rio d a t o t a l o f 474 rainbow t r o u t ,
in c lu d in g 235 m ales and 239 fe m a les, was tra p p e d ,
A t o t a l o f 270,800 eggs
was tak en in t h i s spaw n-taking o p e ra tio n (T able 5 ) ,
Lengths and w eig h ts were taken on rainbow tr o u t in th e 1960 spawning
run in W illow C reek,
Lengths and w eig h ts were a ls o a v a il a b le fo r spawning
-
Table 5»
Rainbow t r o u t c a p tu re d and eggs o b ta in e d d u rin g th e spawns
ta k in g o p e ra tio n in W illow C reek, 1960.
M ales ta k en
Date
A p ril
A p ril
A p ril
May
May
May
9-
13
19
20
3
8
17
90
92
14
22
17
S ta tio n c lo se d
Females tak en
48
45
14
113
19
Eggs o b ta in e d
64,960
46,400
113,920
26,680
27,840
In a d d itio n to th e rainbow t r o u t , 82 a d u lt brown t r o u t were a ls o ta k en
in th e tr a p ; 72 on A p ril 13, 3 on A p ril 2 0 , and 7 on May 11» One a d u lt
brook t r o u t was ta k en on A p ril 20»
f i s h ta k en in 1953 through 1958, e x ce p t fo r 1956»
The ta b u la tio n o f t h i s
m a te r ia l shows a d e c lin e in th e s iz e o f f i s h tak en over t h i s p e rio d (T able
6 ).
T able 6»
Lengths and w eights o f rainbow t r o u t from th e spawning ru n s in
W illow C reek, 1953 -- 1960.
Year
Sex
Number
1953
Male
Female
Male
Female
Male
Female
Male
Female
Male
Female
Male
Female
Male
Female
50
50
14
87
157
368
6
62
53
54
18
57
61
105
1954
1955
1955
1957
1958
1960
Average le n g th
in in c h es
——
2 0 .6
2 0 .4
17.6
19.4
18.1
1 9.0
1 8.7
19.1
18.3
18.8
13.6
17.7
Average w eight
in pounds
3 .9 0
3.40
3 .0 0
3 .10
—
—
—
———
1.61
2.21
2.21
2 .6 2
1.9 9
2 .1 6
0.9 3
1.6 7
A le n g th -fre q u e n c y d i s t r i b u t i o n was p l o t t e d fo r f i s h c a p tu re d in th e
t r i b u t a r i e s in 1960»
The 12- and 1 3 -in c h groups were dom inant w ith 130 and
154 specim ens r e s p e c tiv e ly ?
The 1 8- and 1 9 -in c h groups were n e x t w ith 69
and 72 in d iv id u a ls R e s p e c tiv e ly .
-
At l e a s t some o f th e rainbow t r o u t p la n te d In 1959 and i960 could be.
i d e n t i f i e d by c e r t a i n f i n d e f o r m itie s .
A t o t a l o f 192 f i s h o r 32 p e rc e n t
o f th o se h andled by th e w r ite r d u rin g th e spaw ning-run were i d e n t i f i e d as
h a tc h e ry f i s h .
The m a jo rity o f th e s e were ip th e 12- and 1 3 -in c h groups
and none X ere found to exceed 15.0 in c h e s .
.Of th e 130 f i s h i n th e 1 2 -in c h -
g ro u p 9 72i, o r 55 p e rc e n t p o sse sse d deform ed f i n s 9 and o f th e 154 specim ens
ip th e 1 3 -in c h g ro u p 9 8 1 , o r 52 p e rc e n t showed s im ila r d e f o r m itie s .
The
1 8 - and I 9- in c h groups were e i t h e r from f i s h p la n te d (m o stly f in g e r li n g s )
p r i o r to 1959» Or from w ild f i s h .
A few o b s e rv a tio n s were made on th e spawning movement o f su c k e rs in to
th e t r i b u t a r y s tre a m s .
On A p ril 13» 206 (143 w h ite suC kers and 63 lpnghose
s u c k e rs ) were removed from th e W illpw Crpek t r a p , and on su b seq u en t day's
la r g e undeterm ined numbers were removed,
W illow Creek was weighed and m easured.
A sample Pf 52 su c k e rs from.
These had an a v erag e t o t a l le n g th
o f 14,25 in c h e s and an av erag e w eight o f 1 .2 4 pounds.
E ig h t su c k e rs were
ta k en from Norwegian Creek on. May 7$ b u t none were found in Dry Hollow
C reek.
Qn June 2» a c o n c e n tra tio n o f su c k e rs and t r o u t was observed bn
th e f i r s t r i f f l e above th e r e s e r v o i r in W illow C reek,
A 1 5 0 -fo o t s e c tio n
p f t h i s r i f f l e was shocked.
80. rainbow trouts,
The f i s h tak en in c lu d e d s
13 brown t r o u t and sb.PUt 1.50 s u c k e rs .
Exam ination o f fo u r rainbow, t r o u t
and th r e e brown t r o u t stom achs R evpaled t h a t they had been fe e d in g alm o st
e x c lu s iv e ly Op su ck er eg g s.
—11 —
Spawning S u c c e s s a
The t r i b u t a r y stream s were k e p t under o b s e rv a tio n
f o r t r o u t fr y and f in g e r li n g s from May 27 to SeptembSr 8 .
Dry Hpilow
Creek was dew atered on May 2 8 , e x c e p t fo r a few s c a tte r e d p ools*
p o o ls were in s p e c te d f o r fr y b u t nohe were found*
These
A f r y t r a p , which had
been used s u c c e s s f u lly in o th e r Montana s tre a m s y was p la c e d ip Norwegian
Greek in an a tte m p t to c a p tu re fry*
ed in th e stream U n til A ugust 17»
i t was i n s t a l l e d oh June 3 and rem ain­
D uring t h i s p e rio d n o t one f r y or f i n g e r -
lin g t r o u t was ta k e n a lth o u g h s e v e ra l dace and s c u lp in s were caught*
Re­
p e a te d s e in in g ('"common, s e n s e ” , 1 /8 -in c h mesh) c ap tu red no t r p u t and only
a few su ck er f r y in Norwegian C reek , b u t a la r g e number o f fr y and f i n g e r lin g t r o u t (b ro o k , browh and rainbow ) a s w e ll a s su ck e rs were tak en In
W illow Creek*
Autumn Spawning A c tiv ity *
The t r i b u t a r i e s were k e p t under O bservation;
th ro u g h O ctober and November fo r spawning brown t r o u t , o r t h e i r re d d s .
Only W illow .C reek re v e a le d any spawhipg f i s h , a lth o u g h th e r e was ad eq u ate
w a ter ip a l l th e t r i b u t a r i e s *
The f i r s t re d d was found oh O ctpber 4y and
10 re d d s were observed in. a p p ro x im a te ly two m ile s o f stream between O ctober
4 , and November 2*
A s e c tio n Pf W illow Crpek (a p p ro x im a te ly 300 f e e t ) was sampled fo u r
tim es by ,e le c tr b f is h in g (O ctober 6 , 2 1 , 2 4 , and 28)*
Twenty m ale and
th r e e female, brown t r o u t w ere ta k e n , alo n g w ith. 13 m ale and 11 fem ale brook
t r o u t , and 6 inale and 3 fem ale w h ite fis h *
A ll o f th e s e f i s h were m ature
enough to spawn,*
Two e x p erim en tal g i l l n e ts were p e t n e a r th e mouth o f W illow Creek on
-
Novembeir 2 and two Oh November 3 ,
12-
Teh fem ale ajad fo u r m ale brpvm t r o u t
over 15 in c h e s in t o t a l le n g th , and 11 s m a lle r in d iv id u a ls o f t h i s sp e c ie s
were ta k e n o Nohe Of them showed ev id en ce o f h aving spawned o r b e in g m ature
enough to spawn, w ith th e e x c e p tio n o f one fe m ale.
A ll th e rem ain in g
fem ales had rem napts o f eggs in th e body c a v it y , presum ably frpm th e p r e ­
v io u s se a so n .
Ago arid Groyrth
Age arid grow th d e te rm in a tio n s were niade f o r rainbow t r o u t and brown
tro u ti
F is h were c o lle c te d from W illow Creek R e se rv o ir by g i l l n e t t i n g ,
arid a n g lin g , and from th e t r i b u t a r i e s by e l e c t r o f i s h i n g , s e in in g , and th e
tr a p on W illow C reekf
l e n g th ) .
F is h were m easured to th e n e a r e s t 0 ,1 ip c h ( t o t a l
S c a le sam ples were taken, a n t e r i o r to th e d o rs a l f i n above th e
l a t e r a l l i n e , arid a n n u li were d eterm in ed from p l a s t i c im p re ssio n s w ith th e
a id o f a m ic r o p r d je c to r .
S c a le m easurem ents were made from th e c e n te r o f
th e fo cu s to th e o u te r edge a lo n g th e m id - a n te r io r r a d iu s .
Assuming a
s t r a i g h t l i n e r e l a t i o n s h i p Of s c a le le n g th to body le n g th , th e le n g th o f
th e f i s h a t th e com pletion o f each an n u lu s was d eterm in ed by use o f a
nomograph,
A c o n s id e ra b le number o f s c a le sam ples re v e a le d p a t t e r n s th a t were so
i r r e g u l a r apd d iv e rs e t h a t they could n o t be i n t e r p r e t e d .
Mpst o f th e se
s c a le sam ples were from f i s h betw een 7 and 16 in c h es in t o t a l le n g th th a t
had deformed f i n s , . P r a c t i c a l I y ' a l l o f th e f i s h tak en betw een 9 and 15
in c h e s t o t a l le n g th had i r r e g u l a r p a t t e r n s tin t h e i r s c a l e s , th e s e f i s h
a ls o had deform ed f i n s .
-
13 -
The av erag e c a lc u la te d t o t a l le n g th s f o r rainbow t r o u t a t a n n u li I-V I
were 3 ,2 9 , 7 ,8 6 , 1 2 .9 3 , 1 6 ,5 3 , 1 8 ,8 2 , and 1 8 ,1 ,
The l a r g e s t in d iv id u a l in
th e c o lle c tio n was 2 1 .0 in c h e s in t o t a l le n g th , weighed 3 .0 2 pounds and had
f iv e a n n u li.
No rainbow tr o u t were found to have more th an s ix a n n u li.
The s m a lle s t rainbow tr o u t taken was 3 .6 in c h es in t o t a l le n g th and was
w ith o u t a n n u li.
C a lc u la tio n s from s c a le s o f p re v io u s c o lle c tio n s in
W illow Creek R e s e rv o ir (1949, 1954, and 1955) g e n e r a lly showed g r e a te r
t o t a l le n g th s th an th o se o f th e 1960 c o lle c tio n (T able 7 ) .
rainbow t r o u t was ta k en in 1954.
The l a r g e s t
I t was 2 4 .3 in c h es in t o t a l le n g th ,
weighed 4 .6 2 pounds and had f iv e a n n u li.
T able 7 .
Comparison o f rainbow t r o u t age and growth d e te rm in a tio n s fo r
Montana (number o f specim ens in p a r e n th e s is ) .
L o catio n
W illow Creek R es.
Year
1960
1955
1954
1949
Canyon F e rry Res.
1959
P r ic k le y Pear C r.
1955
M isso u ri R iver
1950
I
II
7.8 6
3 .2 9
(258) (246)
3 .2
8 .4
(55)
(55)
10.2
4 .0
(96)
(96)
8 .6
3 .3
(18)
(18)
3 .4
7 ,2
(13)
(12)
3 .5
6 .6
(747) (270)
3 .2
7 .9
(478) (371)
III
12.93
(233)
1 3.7
(53)
15.6
(95)
14.9
(18)
13.8
(10)
9 .4
(63)
11.1
(168)
IV
16.53
(152)
17.8
(28)
19.4
(87)
17.7
(13)
17.1
(I)
11.8
(10)
13.5
(40)
V
18.82
(68)
2 0 .5
(I)
2 1 .6
(30)
18.3
(3 )
19,0
(I)
16 .7
(I)
1 5.9
(4 )
VI
18.10
(2)
2 1 .0
(3)
16.6
(2)
S e v e ra l age and grow th s tu d ie s have been made on rainbow tr o u t in
M ontana.
Growth was s im ila r fo r ag es I and I I ex cep t fo r P r ic k le y Pear
Creek (B ish o p , 1955) which was l e s s than th a t o f Willow Creek R e se rv o ir a t
age I I .
In f i s h o ld e r than two y e a r s , grow th was g r e a t e s t in Canyon F e rry
—
14-
R e se rv o ir (Graham, 1959), n e x t in W illow Creek R e s e rv o ir, n e x t in th e
M isso u ri R iv er (K a th re in 9 1951), and l e a s t in P r ic k le y P ear CreekThe av erag e c a lc u la te d t o t a l le n g th s fo r brown t r o u t a t a n n u li I - V I lI
were 3 .3 8 , 8 .2 9 , 1 2 .9 9 , 1 5 .6 9 , 1 7 .2 9 , 1 9 .1 3 , 2 2 .9 0 , and 2 4 .4 0 .
The l a r g e s t
and o ld e s t specimen in th e c o lle c tio n was 2 5 .0 in c h es in t o t a l le n g th ,
weighed 7 .5 0 pounds and had e ig h t a n n u li.
The s m a lle s t brown tr o u t in th e
c o lle c tio n was 3 .2 in c h es in t o t a l le n g th and was w ith o u t a n n u li.
The
brown tr o u t grow th r a t e fo r W illow Creek R e se rv o ir was g r e a te r than th a t
re p o rte d by Bishop (1955) fo r ages I I - V I I , com parable to th a t found by
K a th re in (1 9 5 1 ), b u t n o t a s g r e a t as t h a t g iv en by Graham (1959) (T able 8 ) .
T able 8 .
Comparison o f brown tr o u t age and growth d e te rm in a tio n s fo r
Mohtana (number o f specim ens in p a r e n th e s is ) .
Year
L ocation
W illow Creek R es.
Canyon F e rry Res.
P ric k le y P ear C r.
M isso u ri R iver
1960
I
3.38
(140)
1959 4 .2
(67)
1955 3 .8
(908)
1950 3 .9
(127)
II
III
8 .2 9
(125)
10.4
(67)
7 .7
(375)
8.1
(103)
12.99
(113)
14 .3
(35)
11.1
(229)
12.0
(71)
IV
15.69
(91)
17.2
(34)
13.7
(80)
15.3
(47)
V
17.29
(35)
2 0 .7
(9)
16.5
(19)
18.2
(19)
VI
VII
V III
19.13 22.90 2 4 .4 0
(9 )
(3)
(I)
2 3 .6
(3 )
2 0 .2 2 2.2
(5 )
(I )
2 0 .0 2 1 .7 2 2 .2
(3)
(2 )
(5 )
G ill N e ttin g R e s u lts
Three g i l l n e t s e r i e s , c o n s is tin g o f 20 o v e rn ig h t s e t s e ac h , were made
in W illow Creek R e s e rv o ir in 1960.
One s e r i e s was conducted in June (7 -1 2 ),
one in J u ly (1 9 -2 2 ), and one in Septem ber (1 3 -1 4 ).
N ets used were 125 f e e t
long and 6 f e e t deep w ith graded mesh s iz e s ran g in g from 3 /4 - to 2 -in c h
(b a r m e a su re ).
Twenty n e ttin g s t a t i o n s were e s ta b lis h e d (F ig u re I ) .
June S e r i e s .
The w ater in the r e s e r v o i r was a t maximum le v e l and a l l
ARM
WILLOW
ARM
N O R W E G I AN
F ig u re I ,
W illow Creek R e se rv o ir showing n e ttin g and tem p eratu re s ta t io n s
-
16 -
n e ts were s e t on th e bottom a t d e p th s v a ry in g from 10 tci 50 f e e t .
fo llo w in g f is h were ta k e n s
The
118 brown t r o u t , 48 rainbow t r o u t , 2 brook
t r o u t , 2 m ountain w h ite f is h and 1595 w hite and longnose su c k e rs (T able 9 ).
T able 9,
S e t number
I
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
T o ta ls
F ish taken in th e June g i l l n e t s e r i e s , Willow Creek R e s e rv o ir,
1960.
Rainbow
tro u t
Brown
tro u t
Brook
tro u t
I
4
4
4
I
7
3
7
7
3
6
I
3
I
I
—
—
-
—
-
2
2
I
—
-
I
I
3
3
3
7
4
48
W hitefis h
-
—
-
-
—
-
—
-
I
-
-
-
-
—
-
-
-
3
4
10
9
-
-
-
-
-
24
19
6
8
3
118
-
-
I
-
-
-
-
-
-
I
I
-
2
-
2
Suckers
89
96
76
96
71
185
86
84
132
128
48
98
50
50
21
41
44
31
86
83
1595
Maximum d ep th
in f e e t
15
15
20
20
20
20
20
25
15
25
20
15
50
50
45
30
30
20
15
10
Brown t r o u t were tak en in a l l a re a s o f th e r e s e r v o i r , b u t were more abundant
a t d e p th s below 30 f e e t , where 25 p e rc e n t o f th e n e ts c a p tu re d 52 p e rc e n t
o f t h i s s p e c ie s .
Rainbow t r o u t were tak en in most areals o f th e r e s e r v o ir
and showed no marked c o n c e n tr a tio n s .
S u ck ers outnumbered a l l o th e r f i s h in
a l l s e t s r e g a r d le s s o f lo c a tio n ,
J u ly S e r i e s ,
s p illw a y .
The w ater le v e l in th e r e s e r v o i r was s ix f e e t below th e
N ets a t 10 s t a t i o n s were s e t on th e bottom w h ile th e o th e r 10
-
were s e t a t the s u r f a c e .
17 -
The fo llo w in g f i s h were ta k e n :
227 rainbow tro u t,
46 brown t r o u t , 4 brook t r o u t , and 1237 su c k e rs (T ab le 1 0 ).
Table 10.
The 10 bottom
F ish tak en in th e J u ly g i l l n e t s e r i e s , W illow Creek R e s e rv o ir,
1960.
S e t number
3
4
6
8
10
11
13
15
18
19
Total
I
2
5
7
9
12
14
16
17
20
T o tal
Grand T o tal
S et type
Surface
19
99
99
99
99
99
99
99
99
Surface
Bottom
99
99
99
99
90
99
99
99
99
Bottom
Rainbow
trou t
Brown
trou t
Brook
tro u t
—
—
13
4
23
4
4
24
4
38
I
11
126
4
2
19
11
24
7
6
4
10
14
101
16
4
11
4
39
3
4
Suckers
84
10
70
8
3
2
4
7
2
42
232
116
86
82
114
104
89
27
75
91
221
1005
227
46
4
1237
-
-
-
-
-
-
-
-
—
-
-
-
-
7
7
2
-
-
-
-
-
2
I
-
-
S ta tio n depth
in f e e t
15
15
20
20
20
15
40
40
15
10
7
7
15
10
10
10
50
25
25
8
s e t s c ap tu red 101 rainbow t r o u t , 39 brown t r o u t , 4 brook t r o u t , and 1005
s u c k e rs , w h ile th e s u rfa c e s e ts took 126 rainbow t r o u t , 7 brown t r o u t , and
232 s u c k e rs .
Rainbow t r o u t were tak en th ro u g h o u t the r e s e r v o i r w ith the
s u rfa c e s e ts c a p tu rin g 56 p e r c e n t.
Only 15 p e rc e n t o f th e brown tr o u t were
taken in s u rfa c e s e t s , ,and a l l o f th e s e were in the same n e t ( s e t 15) which
f lo a te d over 40 f e e t of w a te r.
In th e bottom s e t s , 30 p e rc e n t o f th e n e ts
-
took 79 p e rc e n t o f th e brown t r o u t .
24 f e e t .
18 -
These n e ts were s e t a t d ep th s below
The 10 bottom s e ts c a p tu re d 81 p e rc e n t o f th e su ck e rs taken in
th is s e r ie s .
Septem ber S e r i e s .
s p illw a y .
The w ater was a t minimum l e v e l ; 15 f e e t below th e
Only 10 o f th e o r ig in a l s t a t i o n s were s u ita b le fo r g i l l n e ttin g
and one n e t was s e t a t th e s u rfa c e and one <3n th e bottom a t each o f th e s e .
The fo llo w in g f i s h were ta k e n s
1742 su c k e rs ( t a b l e 1 1 ).
T able 11.
S e t number
4
8
10
11
13
14
15
16
17
19
T o tal
4
8
10
11
13
14
15
16
17
19
To ta l
Grand T o tal
334 rainbow t r o u t , 101 brown t r o u t , and
The bottom s e ts c a p tu re d 70 rainbow t r o u t , 69
F ish taken in th e Septem ber g i l l n e t s e r i e s , Willow Creek
R e s e rv o ir, 1960.
S e t type
S u rfa c e
tf
99
90
99
99
99
99
99
99
S u rfa c e
Bottom
90
99
99
99
90
99
99
90
99
Bottom
Rainbow
tr o u t
35
33
50
29
26
Brown
tr o u t
—
3
2
-
S uckers
88
168
65
72
31
14
25
94
52
68
677
16
8
33
34
264
I
I
I
13
5
6
32
13
14
4
8
5
I
3
15
7
70
I
I
5
9
14
5
7
12
2
13
69
133
189
154
107
60
18
45
176
94
89
1065
334
101
1742
-
S ta tio n d ep th
in f e e t
15
15
15
24
42
42
40
25
25
20
15
15
15
24
42
42
40
25
25
20
-
19 -
brown t r o u t , and 1065 s u c k e rs , w h ile th e s u rfa c e s e ts took 264 rainbow
t r o u t , 32 brown t r o u t , and 677 s u c k e rs .
A lthough rainbow t r o u t were tak en
in a l l d e p th s and a re a s o f th e r e s e r v o i r 79 p e rc e n t o f them were c ap tu red
ip s u rfa c e s e t s .
Brown, t r o u t were a ls o tak en th ro u g h o u t th e r e s e r v o i r ,
b u t 68 p e rc e n t o f them were c a p tu re d in bottom s e t s .
The bottom s e ts took
61 p e rc e p t o f th e su c k e rs in t h i s s e r i e s .
F is h D is tr ib u tio n in R e la tio n to Tem perature and. W ater L e v e ls » Some
o b s e rv a tio n s were made op te m p e ra tu re f lu c tu a tio n s and w ater l e v e l s .
T em peratures were secu red w ith a r e s i s t a n c e therm om eter a t TO s t a t i p p s in
th e r e s e r v o i r (F ig u re l ) ,
R eadings were ta k ep a t th r e e - f o o t i n t e r v a l s from
s u rfa c e to bottom (T able 1 2 ),
W ater le v e l d a ta were sec u re d from th e Mon­
tan a S ta te W ater B oard,
D pripg th e June g i l l n e t s e r i e s , w ater le v e l s were maximum.
S u rfa ce
'
te m p e ra tu re s ranged from 63,-0° to 6 4 ,0 ° F „, w ith ap av erag e o f 63»7?,
Bottom te m p e ra tu re s ranged from 5 4 ,0 ° a t 60 f e e t to 6 0 ,5 ° F, a t 15 f e e t ,
w ith an av erag e o f 5 6 ,4 ° ,
Brown t r o u t were d i s t r i b u t e d over th e e n t i r e
bottom o f th e r e s e r v o i r , a p p ea rin g in 90 p e rc e n t o f th e n e t s .
This s p e c ie s
was more abundant a t d e p th s below 30 fe e t,- however th e re was po ap p aren t
r e l a t i o n s h i p betw een brown t r o u t d i s t r i b u t i o n and w ater te m p e ra tu re s ,
Raipb.ow t r o u t were n o t abundant b u t were w id ely d i s t r i b u t e d , a p p earin g in
80 p e rc e n t o f th e n e t s .
During th e J u ly g i l l n e t s e r i e s w ater le v e ls were down s ix f e e t .
S u r­
fa c e te m p e ra tu re s ranged from 75*0° to 7 8 ,0 ° F ,, w ith an average, o f 76,39»
Bpttpm te m p e ra tu re s ranged from 6 3 ,0 ° a t 54 f e e t td 7 4 ,5 ° F, a t 3 f e e t .
- 2
T able 12.
-
Water te m p e ra tu re s in Willow Creek R e s e rv o ir, 1960.
Average te m p e ra tu re s in d eg rees F a h re n h e it
fo r a l l s ta t io n s
Date
June 14
J u ly 22
September 12
6 3 .7
63.7
7 6 .3
74.1
6 3 .5
61.1
6 2 .3
60.1
7 2 .9
6 1 .7
7 1 .7
5 9 .4
6 2 .0
7 0 .6
5 9 .3
6 1 .3
6 9 .6
5 9 .0
5 9 .9
6 9 .9
5 8 .9
5 9 .4
6 8 .3
5 9 .0
5 8 .2
6 7 .4
5 9 .0
57.1
5 9 .0
6 6 .9
5 6 .5
6 5 .7
5 9 .0
5 5 .5
6 5 .0
5 9 .0
5 5 .0
5 9 .0
6 5 .0
5 5 .0
6 4 .7
5 8 .3
5 5 .0
6 4 .3
5 8 .3
5 4 .6
6 4 .2
5 8 .3
5 4 .3
6 3 .8
6 3 .7
5 4 .3
5 4 .3
6 3 .3
5 4 .3
5 4 .3
Depth in f e e t
S u rfa c e
3
6
9
12
15
18
21
24
27
30
33
36
39
42
45
48
51
54
57
60
w ith an av erag e o f 6 8 .I 0 o
n e ts .
0
Brown t r o u t were taken in only 35 p e rc e n t o f th e *
Bottom s e ts c a p tu re d 85 p e rc e n t o f th e brown t r o u t tak en in t h i s
s e rie s .
They were p a r t i c u l a r l y abundant in n e ts s e t a t d e p th s below 24
f e e t , where w ater te m p e ra tu re s averaged l e s s than 68° F.
Rainbow tr o u t
appeared in a l l n e ts w ith s u rfa c e s e t s c a p tu rin g 56 p e rc e n t o f th e t o t a l .
During th e Septem ber g i l l n e t s e r i e s w ater le v e ls were a t a minimum
(-15 f e e t ) .
S u rfa c e te m p e ra tu re s ranged from 6 2 .5 ° to 6 5 .5 ° F . , w ith an
av erag e o f 6 4 .0 ° .
Bottom te m p e ra tu re s ranged from 5 8 .0 ° a t 45 f e e t to
6 0 .0 ° F. a t 3 f e e t , w ith an av erag e o f 5 8 .9 ° .
p e rc e n t o f th e n e t s .
Brown tr o u t appeared in 90
They were taken m ost fr e q u e n tly in bottom s e ts where
-
68 p e rc e n t was captured=
21 -
There were no c o n c e n tra tio n s t h a t could be
a t t r i b u t e d to tem peratures=
Rainbpw t r o u t a ls o ap p eared i n 90 p e rc e n t o f
th e n e t s , 79 p e rc e n t b e in g taken in s u rfa c e sets=
S uckers showed w ider
d is p e r s io n in Septem ber than in July=
W hile w ater le v e l s dropped p r o g r e s s iv e ly from June th ro u g h Septem ber,
no r e l a t i o n s h i p was observed betw een d e c lin in g w ater l e v e l s and f i s h d i s ­
t r i b u t i o n , o th e r th an a g e n e ra l o v e r a ll r e s t r i c t i o n =
S p e c ie s Com pO sitioh= The g i l l n e ts took a t o t a l o f 5 ,4 5 6 fish=
The
m ost abundant f is h e s were th e s u c k e rs , which c o n s titu te d 4 ,5 7 4 in d iv id u a ls
com prising 83=83 p e rc e n t o f th e t o t a l =
Of th e rem ain in g 882 f is h s
rainbow
t r o u t made up 69=05 p e rc e n t (609 i n d i v i d u a l s ) , brbwh t r o u t 30=04 p e rc e n t
(265 i n d i v i d u a l s ) , brook t r o u t 0=68 p e rc e n t (6 in d iv id u a ls ) and m ountain
w h ite f is h 0=23 p e rc e n t (2 in d iv id u a ls )=
Of a l l th e rainbow t r o u t ta k e n ,
488 o r 80=1 p e rc e n t had deformed f i n s and were presumed to be h a tc h e ry f i s h
Of th e 1959 and i960 p la n ts =
L e n g th -F re q u en c ie s o f Rainbow and Brown TrO utd
A le n g th -fre q u e n c y
d i s t r i b u t i o n was p l o t t e d f o r rainbow t r o u t tak en in th e th re e g i l l n e t
s e r i e s (F ig u re 2)=
The 1 1 -in c h group was dom inant, h aving 132 in d iv id u a ls =
T his group was follow ed by th e 1 3 -in c h group w ith 117 in d iv id u a ls , and th e
1 4 -in c h group w ith 113 in d iv id u a ls =
Rainbow tr p u t tak en by a n g le r s showed
th e 1 3 -in c h group to be th e m ost numerous with, 619 in d iv id u a ls =
The 14-
in c h group was n e x t w ith 454 specim ens, fo llo w ed by th e lO -in p h group w ith
206 in d iv id u a ls =
■A le n g th -fre q u e n c y d i s t r i b u t i o n was p lo tte d fo r brown t r o u t taken in
th e th r e e g i l l n e t s e r i e s (F ig u re 3)=
The 1 6 -in ch group was dom inant,
■22
620
\
6 00
580
560
FI SH
TAKEN IN G I L L N E T S
54 0
F I SH
TAKEN
520
FISH
TAKEN
IN
BY
ANGLERS
SPAWNING
R U N ----- ■ ------
50 0
48 0
I
I
460
NUMBER
OF
FISH
440
12
LENGTH
F ig u re 2 .
13
IN
14
15
16
17
18
19
20
21
INCHES
L en g th -freq u en cy d i s t r i b u t i o n o f rainbow tr o u t in th e spaw ning,
ru n , g i l l n e ts and c r e e l , 1960.
-
23 -
F I S H T A K EN
TAKEN
BV
NETS
ANGLER S
NUMBER
OF
FISH
FISH
IN G I L L
13 14
LENGTH
F ig u re 3.
IT 18 19 20 21 22 23 24 2 5
IN
INCHES
Length frequency d i s t r i b u t i o n o f brown t r o u t in th e g i l l n e t s
and c r e e l , 1960.
h aving 56 in d iv id u a ls .
T his group was fo llo w ed by th e 1 5 -in c h group w ith
34 in d iv id u a ls , and 1 7 -in c h group w ith 32 in d iv id u a ls .
Brown t r o u t taken
by a n g le r s showed th e 1 7 -in c h group to be dom inant w ith 15 specim ens.
This
was follow ed by th e 1 6 -in c h group w ith 12 in d iv id u a ls and 1 5 -in c h group
w ith 6 in d iv id u a ls .
H arvest
W illow Creek R e s e rv o ir was open to a n g lin g from May 22 th ro u g h Ju ly
15, 1960.
A ngling was p e rm itte d only in t h a t p o rtio n o f W illow Creek
R e s e rv o ir known a s Norwegian Arm (F ig u re 2 ) .
An a tte m p t was made to con­
-
24 -
t a c t o n e -h a lf o f th e a n g le r s , and in v e n to ry t h e i r c a tc h .
A nglers were
in te rv ie w e d a t a checking s t a t i o n ' lo c a te d on, th e only a c c e ss ro a d .
The
fo llo w in g in fo rm a tio n Was ta k e n from each f is h in g p a r ty ; number o f f i s h e r ­
men, number o f h o u rs f is h e d , number o f f i s h ta k e n , apd method o f f is h in g
( from a b o a t or from s h o r e ) .
The sam pling p e rio d was d iv id e d in to th re e s t r a t a ?
s tra tu m I opening
d ay ; stra tu m T I, weekend days and h o lid a y s ; and stra tu m I I I , w eekdays.
a c tu a l count was o b ta in e d f o r th e f i r s t s tra tu m ,
An
In s tra tu m I I O n e-h alf o f
th e S a tu rd a y s , o p e -h a If o f th e Sundays, and one o f th e two h o lid a y s were
c en su sed ,
Ip stra tu m I I I o n e -h a lf o f th e Mondays, T uesdays, Wednesdays;
T h u rsd ay s, and F rid a y s were c en su sed »
O c e ss,
d a ta o
An e s tim a te o f t o t a l c a tc h was made from th e census
E stim a te d t o t a l c a tc h w ith 90 p e r c e n t c o n fid en ce l i m i t s ' fo r s t r a t a
I I and I I I w ere d eterm in ed tti supplem ent th e a c tu a l co u n t o f stra tu m I .
The method o u tlin e d by CTochran (1953, p p , 72-73) was used to make t h i s
e s tim a te and o b ta in co n fid e n ce l i m i t s .
The above e s tim a te was combined
w ith th e t o t a l number Of f i s h in v e n to rie d in stra tu m I fo r th e e stim a te d
t o t a l c a tc h (T able 1 3 ),
T able 13,
, S t r a t a ,..
I
I I and I I I
T o tal
E stim a te d number o f f i s h ta k en by a n g le r s from W illow Creek
R e s e rv o ir, I960,
Loweir c o n fid en ce
■ lim it.
I ; 854
9,377
11,231
.E stim a te
1,854
13,014
14,868
Upper c o n fid en ce
, , lim it
. .
1,854
16,651
18,505
-
25 -
A t o t a l o f 2.9076 a n g le r s was in te rv ie w e d , and 1,725 o f th e s e fis h e d
from b o a ts w h ile 351 fis h e d from s h o re .
The b o a t fish erm en cau g h t 7,436
f i s h f o r an av erag e o f 4.31 f i s h p e r fish e rm a n , a t th e r a t e o f 0.850 f is h
p e r h o u r, w h ile th e sh o re fish erm en took 937 f i s h fo r an av erag e o f 2 .6 7
f i s h p e r fish erm an a t th e r a t e o f 0.455 f i s h p e r h o u r.
Boat and sh o re
fish erm en combined took an av erag e Of 4 .0 3 f i s h p e r fish e rm a n , a t t h e . r a t e
o f 0.775 f i s h p e r h o u r.
C om position o f th e C atch .
Of th e t o t a l f i s h tak en by a n g le rs from
W illow Creek R e se ry O ir, I »941 were examined*
m easured and f i n c o n d itio n n o te d .
F is h were i d e n t i f i e d ,
There were 1,888 rain b o w t r o u t (97.27
p e r c e n t) , 48 brown t r d u t (2 .4 7 p e r c e p t) , and 5 brook t r o u t (0 .2 6 p e rc e n t)
in th e c a tc h .
Rainbow t r o u t av erag ed 12.96 in c h es in t o t a l le n g th , brown
t r o u t 16.73 in c h e s , and brook t r o u t 9.8 8 in c h e s .
F ish w ith deformed f i n s
made up 7 1 .4 p e rc e n t o f th e rainbow ' t r o u t examined in th e c r e e l cen su s.
Marked F is h Recovery
A t o t a l o f 3 ,2 1 0 f i s h was marked e i t h e r by f i n c lip p in g o r jaw ta g ­
g ing t,b o b ta in in fo rm a tio n on d i s t r i b u t i o n and movement o f f i s h in th e
spawning rim s , ahd on th o s e .p la n te d in i9 6 0 .
Of th e s e , 2 ,5 0 0 were from
a h a tc h e ry and 710 were c a p tu re d in th e t r i b u t a r i e s .
Marked f i s h were r e ­
covered by a n g lin g , g i l l n e ttin g and e l e c t r o f i s h i n g .
Recovery o f f i n -
c lip p e d f i s h from a n g le r c a tc h e s was p r a c t i c a l l y n il-, a s a l l f i s h were
clea n e d and f in e were o f te n T ost p r i o r f o e x am in atio n .
Recovery p f F is h Marked in Norwegian C reek.
A t o t a l Of 339 f i s h was
c a p tu re d , marked and r e le a s e d in Norwegian Creek between March 30 and May 7
-
56 -
These in c lu d e d 331 rainb.ow tr o u t (71 w ith jaw t a g s ) , 5 bro o k t r o u t 9 and 3
brown trpU t*
Only 11 rainbow t r o u t were re c o v e re d « Seven o f th e se were
tagged f i s b ta k en by a n g le r s f s ix in th e r e s e r v o i r and one ab o u t two m ile s
above th e r e s e r v o i r in Norwegian C reek,
Four o f th e I l were f i n - c l i p r e ­
c o v e r ie s , • .Two o f th e s e f in - c li p p e d f i s h were tak en by a n g le r s and ohe by
a. g i l l p e t ( s t a t i o n l ) in th e r e s e r v o i r ,
The o th e r was c a p tu re d in
■W illow Creek oh June 2 , by e I e c tf'O fis h in g .
Recovery o f F is h Marked in W illow C reek ,
A, t o t a l o f 249 f i s h was
c a p tu re d , marked and r e le a s e d in W illow Crdek betw een A p ril 13 and ,May 11»
These in c lu d e d 166 rainbow t r o u t (17 w ith jaw t a g s ) , 82 brown tr o u t ( l l
w ith jaw t a g s ) and I brook t r o u t .
F o u rte e n o f th e s e were re c o v e re d | f iv e
were tagged and n in e were c lip p e d ,
Fpur o f th e tagged f i s h were rainbow
t r o u t ta k en by a n g le r s in th e r e s e r v o i r and One was a Orowh t r o u t tak en by
an a n g le r a p p ro x im a te ly I ^ m ile s above th e r e s e r v o i r in N orth WiliOw G reek,
E ig h t f in - c li p p e d rain b o w t r o u t and Ohe brown t r o u t were re c o v e re d .
Of th e
rainbow t r o u t , tine was ta k e n by a n g lin g , and s ix were c au g h t in g i l l n e ts
( s t a t i o n s 5 , 7 , 14, 15, 16, and 20) in th e r e s e r v o i r ,
(June 2) by e l e c t r o - f i s h i n g in W illow Creek*
Cbe Was c ap tu red
The s in g le Ortiwh t r o u t was
ta k e n by e l e c t r o f i s h i n g (O ctober 21) i n th e same c re e k ,
Rectiyery o f F is h Marked in Dry Hollow C reek, ~ A t o t a l p f 122 f i s h
was c a p tu re d , m arked, and r e le a s e d in Dry Hollow Greek betw een A p ril I and
May 7 ,
These in c lu d e d 102 rainbpw - t r o u t (38 w ith jaw t a g s ) , 10 Orowh t r o u t
and id brook t r o u t ,
th e r e s e r v o i r .
Qnly s ix r e c o v e r ie s were made and a l l w ere taken, in"
Three tagged rain b o w t r o u t were tak en by a n g le r s , , Qie f i n -
-
27 - '
c lip p e d f i s h yifas' re c o v e re d by an a n g le r and two were taken; g i l l n e ttin g
( s t a t i o n 9)=
R ec o v e ry o f Marked H atch ery - F is h .
.Qn May I b 9 2,5.00 f in - c lip p e d (6 -9
in c h ) rainbow tro .u t were p la n te d in W illow Arm o f Willpw Creek R e s e rv o ir,
Only 23 o f th e se were re c o v e re d .
Two were ta k e n by e l e c t r o f i s h i n g in
W illow C reek; One on O ctober 21 and one on O ctober 2 4 ,
f i s h were ta k e n by g i l l n e t t i n g in th e r e s e r v o i r ,
each s t a t i o n were a s fo llo w s :
The rem aining 21 '
Tjhe number ta k en a t
I f i s h a t s t a t i o n 4s> 2 a t 8 , I a t. 9,' 2 a t
10, 4 a t 11, I a t 13, I a t 14, I a t 15, 4 a t 17a I 4 t 18, and 3 a t 191 •
Only 31 o f th e 710 f i s h t h a t Wbre marked in th e t r i b u t a r i e s d u rin g
th e spawning seaso p were re c o v e re d .
re s e rv o ir.
These were, w id ely d i s t r i b u t e d ip th e
One in d iv id u a l f in - c li p p e d in NprWegian Greek sometime between
March 30 and May 7 , was ta k e n by e le c t r p f i s h i n g in. W illow Greek on June 2 ,
T his f i s h tr a v e le d ap p ro x im a te ly 4& m ile s which was th e g r e a t e s t d is ta n c e
re c o rd e d fo r any f i s h .
A ll marked h a tc h e ry f i s h were p la n te d in W illow Arm o f th e r e s e r v o ir
p e a r th e i n l e t "
Two o f th e r e c o v e r ie s were made in W illow G reek, 10 in
W illow Arrii, and 11 in. Norwegian Arm,
Summary
I,
O b se rv a tio n s were made on th e spaw nings grow th, d i s t r i b u t i o n , movement;,
and h a r v e s t o f tr o u t in ISillow Creek R e se rv o ir from March 27, through
November 5,,- i9 6 0 ,
2i
The o n ly s u c c e s s fu l re p ro d u c tio n was o b serv ed ip W illow C reek;
Av­
e ra g e s iz e o f rainbow tro u t, ta k en ip th e spawning tr a p on W illow Creek
—
28 —
h as d e c lin e d frdm 20»42 i n c h e s - t o t a l le n g th arid 3 .0 8 pounds in 1954, to
16.19 in c h e s t o t a l le n g th arid I »38 pounds in I9 6 0 .
3.
Of rainbow trov-t observed in spawning ru n s , 32 p e rc e n t were i d e n t i f i e d
a s f i s h p la n te d in 1959 d r I960.
4.
Growth r a t e Of rainbow t r o u t was l e s s in 1960 than in p re v io u s y e a rs
(1949, 1954, and 1955)„
5.
D is tr ib u tio n o f t r o u t in th e r e s e r v o i r ap p eared to be c o r r e la te d w ith
w ater te m p e ra tu re s .
Rainbpw t r o u t were m ost evenly d i s t r i b u t e d in th e
r e s e r v o i r when w ater te m p e ra tu re s were w arm est, b u t were c o n c e n tra te d
p e a r th e s u rfa c e when w ater te m p e ra tu re s were copI .
6.
Brown t r o u t were m ost r e s t r i c t e d a t maximum w ater te m p e ra tu re s , and
w ere.m ost abundant n e a r th e bottom i n a l l g i l l n e t s e r i e s .
7.
The game f i s h caught by g i l l n e t s in c lu d e d , 69=05 p e rc e n t rainbow tr o u t,
3 0 .04 p e rc e n t brown t r o u t , 0.6 8 p e rc e n t brook t r o u t , and 0 .2 3 p e rc e n t
m ountain w h ite fis h b
8»
A t o t a l o f 80.1 p e rc e p t o f rainbow t r o u t tak en in g i l l n e ts was be­
lie v e d to be f i s h p la n te d in 1959 and 1960.
9.
A n g lers took an e stim a te d 14, 868 f i s h from W illow Creek R e se rv o ir d u r?
ing th e s ix week f is h in g seaso n in i9 6 0 , w ith an a v erag e o f 4 .0 3 f is h
p e r fisherm an a t a r a t e o f Oi775 f i s h p e r h o u r.
10.
The a n g l e r s ’ c a tc h was composed o f 97.27 p e rc e n t rairibpw t r o u t , 2 .4 7
p e rc e n t brown t r o u t and 0.26 p e rc e n t brook t r o u t .
11.
Of rainbow t r o u t tak en by a n g le r s , 7 1 s4 p e rc e p t were i d e n t i f i e d as f i s h
p la p te d i n . 1959 and 1960=
12«'
T h irty -o n e o f 7 1 0 'f i s h marked in th e t r i b u t a r i e s . w e f 6 re c o v ere d and
found to be w id ely d i s t r i b u t e d in th e r e s e r v o i r and t r i b u t a r i e s /
13«
Marked h a tc h e ry f i s h p la n te d in WiJrlow Arm were a ls o w idely d i s t r i b u t e d
b e in g re c o v e re d in b o th arms o f th e r e s e r v o i r and i p W illow C reek«
L i te r a tu r e C ite d
B ishop, C lintO h G« 1955»
P ear .Greek, Montana *
C ochran, W illiam G« 1953«'
New Y ork, pp» 724-73«
Age, grow th and c o n d itio n o f tr o u t in P r ic k le y
T ra p s , Am, M icro s, Soc», 74 ( 2 ) : 134-145»
Sam pling T ech n iq u es^
John/W iley and Cops IncZ
Graham, R ic h a rd , 1959. Age and gro w th , bottom sample and m is c e lla n e o u s
s t u d i e s . Job com pletion rep,O rtj Montana F is h and Game D epartm ent,
D in g le -Jo h p sp n p r o j e c t number F -2 3 -R -2 , May, 1959.
K a th rP in , Jo sep h W« 1951, Growth r a t e o f fo u r s p e c ie s Of f i s h in a
s e c tio n o f th e M isso u ri R iv er betw een H p lte r Dam and C ascade, M optapa,
T ra n s « Am. F is h , S e e ., 80s 9 3 -9 8 .
N elson, Wesley C» 1955. Green M ountain R e se rv o ir s t u d i e s , 1949-1950»
Col or a dp, D epartm ent p f Game and F is h . 214 pp«,
S h a rp e , F ran k . 1959. I n v e s tig a tio n Of Shadow M ountain t r o u t f is h e r y .
C olorado C o o p erativ e f i s h e r i e s re s e a rc h u n i t . Q u a rte rly R e p o rt,
Vtilo 5 J u ly 1958 to May 1959, p p . 68-72.
MONTANA STATE UNIVERSITY LIBRARIES
762 1001 5223
(CP) J 1A r/
lp r
Xj^tvWS Dvcfcorsovi v
ii< s a io