Size, abundance, and seasonal habitat utilization of an unfished trout population and their response to
catch and release fishing
by Denise Wilson Vore
A thesis submitted in partial fulfillment of the requirement for the degree of Master of Science in Fish
and Wildlife Management
Montana State University
© Copyright by Denise Wilson Vore (1993)
Abstract:
Few studies have assessed the effects of catch and release fishing on a previously unfished trout
population or provided information on seasonal habitat use. Four sections of Rattlesnake Creek were
studied from March 1985 through February 1987. I examined the effects of catch and release fishing on
a population of trout that had not been fished for 45 years. Seasonal and diel habitat use were also
evaluated. Cutthroat, bull, and brook trout were present in Rattlesnake Creek. Size and abundance of
cutthroat and bull trout were large compared to other similar streams. Two years of catch and release
fishing had no measurable effect on size or abundance of trout. Among all cutthroat trout tagged, 22%
were recaptured and 68% of. those over 400 mm total length were caught and released. These and other
data collected on Rattlesnake Creek indicate the extreme vulnerability of cutthroat trout to angling.
Cutthroat trout behavior during late spring days was related to spawning. Feeding was the dominant
activity during summer days and cover seeking dominated during winter days.
Diel shifts were most noticeable during winter. Twice as many trout were counted at night during the
winter. Winter night . counts were similar to summer day counts. SIZE, ABUNDANCE, AND SEASONAL HABITAT UTILIZATION
OF AN UNFISHED TROUT POPULATION AND THEIR
RESPONSE TO CATCH AND RELEASE FISHING
by
Denise Wilson Vore
A th e s is subm itted in partial fulfillm ent
o f th e requirem ent fo r th e d egree
of
Master o f S cience
in
F ish and Wildlife Management
MONTANA STATE UNIVERSITY
Bozeman, Montana
April 1993
YV2*(
ii
APPROVAL
of a th e s is subm itted by
Denise Wilson Vore
This th e s is has been read by each member o f th e th e s is
committee and has been found to be sa tisfa cto ry reg a rd in g content,
E nglish u sa g e, format, citatio n s, bibliographic s ty le , and
c o n siste n c y , and is read y for subm ission to th e College of Graduate
S tu d ies.
^ < 2
Date
A pproved for th e Major Department
22 April 1%
Head, Major Department
Date
A pproved for the College o f Graduate S tu d ies
j - / ? / T J
Date
Graduate Dean
iii
STATEMENT OF PERMISSION TO USE
In p r e se n tin g th is th e s is in partial fulfillm ent of th e
requirem ents for a m aster’s d egree a t Montana State U n iv ersity , I
a gree th at th e Library shall make it available to borrow ers under
r u les of th e Library.
If I have in d icated my in ten tion to co p y rig h t th is th e s is by
in clu ding a c o p y r ig h t notice p age, co p y in g is allowable on ly for
sch olarly p u rp o ses, c o n siste n t w ith "fair use" as p rescrib ed in the
U.S. C opyright Law.
R equests fo r perm ission for exten d ed
quotation from or rep rod uction of th is th e s is in whole or in parts
may be granted on ly b y th e c o p y r ig h t holder.
Sign ature
Date
7
7
V
ACKNOWLEDGMENTS
My sin cere th an k s to th o se who w ere in volved in all p h ases of
th is stu d y .
I am g ra tefu l to th e follow ing groups for th eir
in te r e st and a ssista n c e w ith funding:
th e Trout and Salmon
Foundation, Sp ort F ish ery R esearch Foundation, Foundation for
Montana Trout, National and local Trout Unlimited, W estern Montana
F ish and Game A ssociation and th e Inland Empire Fly F ishing Club.
I would lik e to exten d a sp ecia l th a n k s to th e follow ing
in d ivid u als for th eir a ssista n ce .
Don P eters and D ennis Workman of
th e Montana Departm ent of Fish, Wildlife and Parks con trib u ted
invaluable a ssista n c e du rin g all p h a se s of th e stu d y .
Gary Blount
w orked in p a rtn ersh ip to develop th e p ro ject and c o lle ct all
p ortion s of th e data.
Marshall Bloom and Pete T est of Trout
Unlimited w ere instrum en tal in g e ttin g th e p ro ject in itiated .
Dr.
Bob White su p p orted th e p ro ject and a s sis te d in preparation of th e
m anuscript.
Drs.. Calvin Kaya and Lynn Irb y critica lly review ed th e
m anuscript.
Ginger Thomas, Ken Gutowski, and Ron S n y d er provided
ad vice, encouragem ent, and ex p ertise in sta tistic a l a n a ly sis,
in s e c t a n a ly sis (not in clu d ed ) and field work tech n iq u es.
TABLE OF CONTENTS
Page
APPROVAL............................................................... ...................................
ii
STATEMENT OF PERMISSION OF U S E ..........................................
iii
VITA ...............................................................................................................
iv
ACKNOWLEDGEMENTS.....................................
.
.
...........................
v
TABLE OF CONTENTS...............................................................................
vi
LIST OF T A B L E S ...........................................................................................v iii
LIST OF FIG U R ES....................................................................................
xi
ABSTRACT...........................................................................................................xiii
INTRODUCTION.........................................................................................
STUDY A R E A ..................................... ....................................................
METHODS
I
.
4
....................................................................................................
7
S tu d y S e c t i o n s ..........................................
C utthroat Trout G e n e t i c s ..........................................................
Population E s t i m a t e s ....................................................................
Creel C e n s u s ....................................................................................
F ish M ovem ent...............................................
Water Tem perature and D is c h a r g e ..........................................
Habitat V a r ia b le s...............................................
7
7
8
10
11
12
12
R E S U L T S ......................................................................................... .....
.
Population C h a r a c t e r is t ic s ...............................................................
S p ecies Com position..........................................................................
G enotype D e te r m in a tio n ...............................................................
Trout S i z e ....................................
Population A b u n d a n ce ....................................................................
Creel C ensus ............................................................................................
A ngler Hours and P ressu re .
Catch and Catch Composition .....................................................
R ecapture R a t e s ....................................................
M ovem ent....................................................................................
15
15
15
15
18
20
25
25
29
29
31
v ii
TABLE OF CONTENTS - Continued
Page
H a b ita t.................................................................................................... .
Habitat C h a r a c t e r i s t i c s ...............................................................
T em peratures and D is c h a r g e .....................................................
Habitat U se and B e h a v i o r ...............................................................
D IS C U SSIO N ...................................................................................
33
33
37
37
58
Population C h a r a c t e r is t ic s ...............................................................
S p ecies Com position. .
Trout Size and A b u n d a n c e ..........................................................
Snorkel M e t h o d ....................................
A ngler U se and C a tch .........................................................
Seasonal Movement P a t t e r n s ..........................................................
Seasonal Habitat U tilization and B ehavior . . . . . . .
58
58
61
63
65
67
68
LITERATURE C I T E D ...............................................................................
74
APPEN D IC ES...............................................................................................
83
Appendix A - T a b l e s ..........................................................................
84
Appendix B - F ig u r e s ..........................................................................
95
v iii
LIST OF TABLES
1.
C lassification o f su b str a te material (P latts 1979) .
. 13
2.
Numerical r a tin g s u sed to c la s s ify stream bank
environm ent (P latts, 1 9 7 9 ) ..................................................... 14
3.
Pool q u ality ratin g criteria (P latts, 1979) . . . . .
4.
Comparison of tr o u t le n g th (mm) and w eigh t (gm) by
stream sectio n in R attlesnake Creek, 1985 and 1986 . 19
5.
Growth r a tes of cu tth ro a t tro u t determ ined from
recap tu re m easurem ents, 1985 and 1986.......................... 21
6.
Summer and fall m a rk /recap tu re e ffic ie n c ies (%) in
R attlesnake Creek, 1985 and 1986 ..................................... 21
7.
Comparison o f 1985 and 1986 summer daytime
population estim ates for fou r sectio n s of
R attlesnake Creek. C onfidence in terv a ls are shown
in p a r e n th e se s. .................................................
14
26
8.
Comparison of 1985 and 1986 fa ll daytime
population estim ates in th ree sectio n s of R attlesnake
Creek. C onfidence in ter v a ls are shown in
p a r e n th e s e s ....................................................................................... 26
9.
Total estim ated a n g le r s, h ou rs fish e d , and
cu tth ro a t (Ct) cau gh t per hour, R attlesnake Creek,
April th ro u g h Septem ber, 1985 and 1986 . . . . . 2 7
10.
Number o f cu tth ro a t tro u t marked and reca p tu red by
an glin g and size d istrib u tio n in 1985 and 1986. . . 30
11.
Movement o f cu tth ro a t tro u t based on tag r e tu r n s,
1985 and 1986. Only movement o u t of sectio n ta g g ed
is r e c o r d e d ....................................................................................... 32
12.
Number, size , and direction o f tr a v e l of tro u t
trap p ed in R attlesnake Creek, 1986 . '............................. 32
ix
LIST OF TABLES - C ontinued
Table
13.
Page
D irectional movement, by size c la ss, of cu tth ro a t
tro u t trap p ed in R attlesnake Creek, July 21October 3, 1986
34
14.
Habitat data collected an R attlesnake Creek,
Septem ber, 1986 ........................................................................... 36
15.
Number o f cu tth roat tro u t marked, cap tu red , and
recap tu red in S ectio n s I and II of R attlesnake
Creek, sp rin g 1985 ...................................................................... 39
16.
Comparison of cu tth ro a t tr o u t abundance du rin g
fall 1985 and 1986 sn ork el co u n ts in sec tio n s I,
II, and III of R attlesnake Creek. Water
tem p eratures are show n in p a r e n t h e s e s ...................... 47
17.
Summer (su ) 1985, fall 1985, and w inter (w)
1985-1986 daytim e cu tth ro a t co u n ts and w inter
1985-1986 brook and bull tr o u t cou n ts in S ection I
o f R attlesnake C r e e k .................................................................. 49
18.
Number of cu tth roat, brook and bull tro u t cou n ted ,
by hab itat ty p e , in R attlesnake Creek, 1985-86. . . 50
19.
Summer (su ), fa ll (f), and w inter (w) day and
n ig h t cu tth ro a t cou n ts for sec tio n II of R attlesnake
Creek, 1985. Also inclu ded are F ebruary 10, 1986
daytime(W) and nighttim e (N) co u n ts for brook and
bull tr o u t............................................................................................ 52
20.
Number o f th re e sp e cie s
sectio n II of R attlesnake
1987 du rin g th e day (W)
summer (S), fall (F) and
21.
Summer (su) 1985 and 1986, fa ll 1985 and 1986,
and w inter (w) 1986-87 daytime cu tth roat tr o u t
co u n ts in sectio n III of R attlesnake Creek . . . .
of tr o u t o b serv ed in
Creek, January 9,
and n ig h t (N) compared to
w inter (W) 1985-86 . . . . 55
57
22.
R attlesnake Creek w ater a n a ly sis, 10/28/85 and
12/16/86. Data from Mountain Water Company,
M i s s o u l a ......................................................................................... 85
23.
Location of stu d y sectio n s and landm arks in th e
R attlesnake Creek d r a i n a g e ................................................86
'x
LIST OF TABLES - C ontinued
Table
Page
24.
Sample c re e l c e n su s form u sed in th e v o lu n teer
c re e l box, 1985 and 1986.......................................................... 86
25.
Allele fr e q u e n c ie s at th e loci th a t d ifferen tiate
w estslo p e cu tth ro a t and rainbow tro u t in sam ples
co llected from R attlesnake Creek in 1985 and 1986.
The allele ch a r a cter istic s of w estslo p e cu tth roat
tro u t a t each locu s is liste d f i r s t ..................................... 87
26.
Trout population estim ates fo r sectio n I (0.6 km) of
R attlesnake Creek, 1985 .......................................................... 88
27.
Trout population estim ates fo r sectio n II (0.6 km) of
R attlesnake Creek, 1985 .......................................................... 89
28.
Trout population estim ates for sectio n III (0.6 km) of
R attlesnake Creek, 1985 .......................................................... 90
29.
Trout population estim ates fo r sectio n IV (0.6 km) of
R attlesnake Creek, 1985 .......................................................... 90
30.
Trout population estim ates fo r sectio n I (0.6 km) of
R attlesnake Creek, 1986 .......................................................... 91
31.
Trout population estim ates fo r sectio n II (0.6 km) of
R attlesnake Creek, 1986 .......................................................... 92
32.
Trout population estim ates for sectio n III (0.6 km) of
R attlesnake Creek, 1986 .......................................................... 93
33.
Trout population estim ates fo r sectio n IV (0.6 km) of
R attlesnake Creek, 1986 ..................... .................................... 94
xi
LIST OF FIGURES
F ig u r e
Page
1.
Drainage map of R attlesnake Creek and studysection locations
..................................... 5
2.
Seasonal sp e c ie s com position and d istrib u tion in
sectio n III, IV and total sp e c ie s com position on
R attlesnake Creek, 1985, 1986, and 1987 ..................... 16
3.
Seasonal sp e c ie s com position and d istrib u tio n in
sectio n I, and II o f R attlesnake Creek, 1985, 1986,
and 1987 . .
..................... .................................................... 17
4.
Estim ated num ber o f cu tth ro a t tro u t by size c la ss,
season , and sectio n (0.6 km) in R attlesnake Creek.
C onfidence in ter v a ls show n in Tables 28, 29, 32,
and 33, A ppendix A ....................................................................... 23
5.
Estim ated number of cu tth ro a t tr o u t by size c la ss,
season , and sectio n (0.6 km) in R attlesnake Creek.
C onfidence in terv a ls show n in Tables 30, 31, 34,
and 35, Appendix A ....................................................................... 24
6.
Estimated a n g lers in two a rea s of R attlesnake Creek
du rin g w eek d ays and w eek en d d ays, 1985 and 1986. 28
7.
L ength fr e q u e n c ie s o f cu tth ro a t, brook, and bull
tr o u t trap p ed in R attlesnake Creek betw een Ju ly 21
and October 3, 1986
35
8.
Stream d isch a rg e and mean tem peratures ta k en on
R attlesnake Creek below B eeskove Creek from
June 1985 th rou gh F ebruary 1987 ..................................... 38
9.
Number o f cu tth ro a t tro u t < 200 mm total le n g th
cou n ted in sec tio n s I-III du rin g th e day in
R attlesnake Creek, summer and fa ll 1985 and 1986
10.
11.
. 43
Number of cu tth roat tro u t > 200 mm total le n g th
cou n ted season ally during th e day in sec tio n s I
and II of R attlesnake Creek, 1985 and 1986 . . . .
44
Number o f cu tth ro a t tro u t > 200 mm total le n g th
counted season ally du rin g th e day in sec tio n s III
and IV of R attlesnake Creek, 1985 and 1986 . . . .
45
xii
LIST OF FIGURES - C ontin ued
F ig u r e
12.
13.
Page
L ength fr e q u e n c y d istrib u tio n o f cu tth roat tr o u t
captu red in sec tio n s I-IV o f R attlesnake Creek,
summer 1985
96
L ength fr e q u e n c y d istrib u tio n o f cu tthroat tro u t
cap tu red in sec tio n s I-IV o f R attlesnake Creek,
summer 1986
97
14.
Age and le n g th , determ ined from sca les, of
cu tth ro a t tr o u t in sec tio n s I and II of
R attlesnake Creek, 1985 ........................................................... 98
15.
Age and le n g th , determ ined from sca les, of
cu tth ro a t tr o u t in sec tio n s III and IV of
R attlesnake Creek, 1985 ...........................................
99
xiii
ABSTRACT
Few stu d ie s have a s s e s s e d th e e ffe c ts of catch and release
fish in g on a p r e v io u sly u n fish ed tro u t population or provided
inform ation on season al hab itat u se. Four sectio n s of R attlesnake
Creek w ere stu d ied from March 1985 th ro u g h F ebruary 1987. I
examined th e e ffe c ts of catch and relea se fish in g on a population of
trou t th at had not been fish e d for 45 y ea rs. Seasonal and die!
habitat u se w ere also evaluated. C utthroat, bull, and brook trout
w ere p r e se n t in R attlesnake Creek. Size and abundance of
cu tth roat and bull tro u t w ere large compared to o th er similar
stream s. Two y ea rs o f catch and relea se fish in g had no m easurable
e ffe c t on size or abundance of trout. Among all cu tth ro a t tro u t
ta g g e d , 22% w ere recap tu red and 68% of. th o se ov er 400 mm total
le n g th w ere ca u g h t and released . T hese and oth er data collected
on R attlesnake Creek ind icate th e extrem e v u ln era b ility o f cutthroat
tro u t to an glin g. C utthroat tro u t behavior during late sp rin g days
was related to spaw ning. F eeding was th e dominant a c tiv ity during
summer d ays and co v er seek in g dominated during w in ter days.
Diel s h ifts w ere most noticeable du rin g w inter. Twice a s many
tr o u t w ere cou n ted at n ig h t du rin g th e w inter. Winter n ig h t .
cou n ts w ere similar to summer day co u n ts.
I
INTRODUCTION
Catch and relea se fish in g was fir s t in stitu te d in th e Great Smokey
Mountains National Park in 1954 (B arnhart 1989).
It is cu rren tly u sed
to e sta b lish and maintain high q u ality fish e r ie s by d ecrea sin g angling
m ortality.
S ev era l stu d ie s have show n th e e ffe c ts o f ca tch and
relea se fish in g (A nderson and N ehring 1984, Thurow and Bjornn 1978,
Varley and G ressw ell 1988).
However, th ere have b een few
op p ortu n ities to stu d y th e e ffe c ts o f ca tch and relea se fish in g on a
p r e v io u sly u n fish ed tro u t population.
R attlesnake Creek was clo sed to fish in g for 45 y e a rs.
p rotected as M issoula, Montana’s m unicipal water su p p ly .
It was
In 1985, a
25 km sectio n o f R attlesnake Creek, above th e con flu en ce of B eeskove
Creek, was opened to catch and relea se fish in g .
Approxim ately 12 km
immediately below B eeskove Creek rem ains closed to fish in g .
This stu d y was d esig n ed to determ ine th e ch a r a cter istic s of an
u n fish ed tro u t population and evalu ate its resp o n se to catch and
relea se an glin g.
With th e recen t d eclin e in many in terio r cutthroat
tr o u t pop ulations (Behnke 1972) and th eir known v u ln era b ility to
an glin g (MacPhee 1966), it is becom ing in crea sin g ly im portant th at we
u n d erstan d the dynam ics of u n fish ed populations and th e e ffe c ts of
an glin g on rem aining pop ulations.
R esults from th is stu d y will
p rovid e a p oin t o f refer en ce for com paring tro u t pop ulations in
r ela tiv ely p r istin e sy stem s w ith th o se in h eavily im pacted and
2
managed stream s.
U ntil we u n d erstan d th e str u c tu r e of u n disturbed
fish e r ie s and th eir hab itats, p rotection and enhancem ent effo rts will
lack both a rational con text and e ffe c tiv e direction.
Population
abundance, size, habitat u se, and sp e c ie s com position of tro u t in
R attlesnake Creek w ere th e elem ents examined in th e stu d y .
A bundance and size of tro u t w ere exp ected to exceed th a t of other
sim ilar-sized , b u t fish e d , stream s.
Seasonal ch a n g es in abundance and habitat u se w ere also
in v e stig a te d .
Limited inform ation is available about seasonal
flu ctu ation s in tro u t populations or th eir habitat requirem ent during
th e late fall and w inter p eriod s in tem perate la titu d es.
Collection of
inform ation during late fall and w inter can be d ifficu lt due to icing,
su b zero tem p eratu res, and snow.
S tu d ies w hich have evaluated
season al population flu ctu atio n s and habitat use have concen trated on
ju ven ile anadrom ous fis h e s (Taylor 1988, Bustard and N arver 1975,
Hillman and G riffith 1987, and E v erest e t al. 1985).
- Seasonality has
been in v e stig a te d to a le s s e r ex ten t in brook and brown tro u t
populations (Cunjak and Power 1986 & 1987, Hartman 1963, Maciolek
and Needham 1952, Chisholm and Hubert 1987).
Seasonal and diel
flu ctu a tion s in cu tth roat trou t ( O n corh yn ch u s c la rk i lew isi)
abundance, habitat u se, and behavior w ere evaluated in th is stud y.
S p ecific o b je c tiv e s of my stu d y w ere to:
I.
Determine population abundance, size, and sp e c ie s composition
in two u n fish ed sectio n s and two fish ed sec tio n s of
R attlesnake Creek.
3
2.
Conduct a c re e l c e n su s to determ ine an gler d istribu tion ,
an g ler u se , catch, ca tch com position, and ca tch p er unit
effo rt.
3.
Id en tify seasonal movement p a tte rn s of tr o u t in R attlesnake
Creek.
4.
D escribe season al and diel cu tth ro a t trou t hab itat u se and
behavior.
4
STUDY AREA
The R attlesnake Creek drainage is located in w est cen tral
Montana, 8.3 km . n orth of M issoula (F igure I).
The drainage in clu d es
approxim ately 21,053 ha and is w ithin th e Lolo National Forest.
The gen eral top ograp h y of th e drainage is m ountainous with
glacially formed v a lle y s.
Geologic p a ren t material in th e area in clu d es
arg illite, q u artzite, and lim estone o f th e Precambrian B elt ser ie s as
w ell as Cambrian sh a les and lim estones (Nelson & Dobell 1961).
Climate
of th e region is sem i-arid with an a v era g e annual p recip itation of 32
cm (Knoche 1968).
V egetation v a r ies from a sp r u c e -fir fo r e st in th e up p er drainage
to an open p in e-la r ch fo r e st below Franklin Bridge (F igure I).
and sh ru b s of th e riparian area include:
T rees
cottonwood ( P qpulus
tric h o c a rp a ), alder {A lnus ru b ra ), willow (Salix sp p .), and rose (Rosa
sp p .).
O ccasionally th e v a lle y bottom op en s up in to small g r a ssy
meadows.
F escu es ( F estu ca sp p .), w h ea tg ra sses (A g ro p yro n sp p .),
p in e g r a sse s ( C alam agrostis sp p .), and blue join t ( C alam agrostis spp.)
are th e most common gram inoids (Adelman 1979).
R attlesnake Creek o rigin a tes on th e flan k s of McLeod and
T riangle p eak s, and flow s so u th -so u th w e st to its co n flu en ce with th e
Clark Fork o f th e Columbia River a t M issoula (F igure I).
ord er stream w ith a gravel, rubb le su b stra te.
It is a th ird
The w atersh ed is
ch aracterized by r ela tiv ely h igh peak d isch arge per u n it area (Van
der Poel 1979).
A verage annual d isch a rg e during th e stu d y period
5
SCALE
Snorkellng transects - (I), (II), (III), and (IV)
Figure I.
Drainage map of Rattlesnake Creek and study section
locations.
6
was 41.9 c fs.
Peak d isch arge u su a lly o ccu rs in May or ea rly June.
The creek d e sce n d s 1613 m in 37.0 km fo r a mean g ra d ien t of 4.3%;
mean g rad ien t in th e stu d y sectio n s is 1.75% (USFS-Lolo 1976).
Water
pH r a n g e s from 6.6 to 7.6 and w ater alkalinity v a r ies from 13 to 21
m g/L. A dditional w ater chem istry data co llected by th e Mountain Water
Company are inclu ded in Table 22, Appendix A .. R attlesnake Creek’s
nine p eren n ial tr ib u ta r ies inclu de Wrangle, Lake, and High Falls
c r e e k s, w hich origin ate from glacial lak es.
Porcupine, E ast Fork of
R attlesnake, B eesk ove, Pilcher, F raser and Spring C reeks originate
from sp r in g s.
More th an 40 lak es are located in th e u p p er drainage.
From 1956 to 1964, 52,800 m^ o f tim ber w ere h a r v e sted from Lake
Creek, Wrangle Creek, and up per R attlesnake Creek d rain ages
(Adelman 1979).
th e same period.
Cattle grazin g o ccu rred along Sp rin g Creek during
C urrently, th e R attlesnake Creek drainage is
managed prim arily as a w atersh ed and secon d arily a s a recreational
area (USFS Management Plan, 1984).
A 12.2 m -high dam, 4 km
upstream from th e mouth, p r e v e n ts all upstream fish m igration from
th e Clark Fork R iver.
A natural 4.6 m fa lls located above High Falls
Creek is also an upstream m igration barrier.
Common recreational
a c tiv itie s in th e R attlesnake Creek drainage are cam ping, fish in g ,
mountain b ik in g, horseb ack rid in g, and hiking.
F ish in g regu lation s
prohib it an glin g from th e dam upstream to B eeskove Creek.
Catch
and relea se fish in g is allowed from B eeskove Creek to th e headw aters.
7
METHODS
S tu d y Section
Four 610 m stu d y sec tio n s w ere sele c te d on R attlesnake Creek
(F igure I).
S ection s I and II w ere esta b lish e d in th e c lo se d -to -
fish in g area below B eeskove Creek.
Section I was located in th e same
area as th e Montana Department of F ish, Wildlife, and Parks 1984
s u r v e y (Don P e te r s, MDFWP, person al communication).
Section II was
sele c te d b ecau se of it s similar hab itat and close proxim ity to the ca tch
and relea se fish in g area (sectio n III).
Section III was located
imm ediately above. B eeskove Creek w here h ea v y fish in g p r e ssu r e was
anticipated.
S ection IV, near High Falls Creek, was se le c te d to
r e p r e se n t sp e c ie s com position and fish in g p r e ssu r e in th e upper
drainage.
This sectio n was 15.3 km from th e n ea rest road, above a
long cascad e and se v e r a l beaver pon ds.
The lower boundary of each
sectio n was perm anently marked w ith an gle iron p o sts (Table 23,
Appendix A).
C utthroat Trout G enetics
C utthroat tr o u t w ere sampled from R attlesnake Creek in 1985 and
1986 for g en o ty p e determ ination.
The 1985 sample (N=30) was
collected above High Falls Creek (F igure I) and th e 1986 sample
(N=30) w as tak en from th e Pilcher Creek area.
Sam ples w ere
imm ediately placed on ice and d eliv ered to th e U n iv e r sity of Montana
8
g e n e tic s la b o ra to ry fo r a n a ly s e s .
T h ro u g h e le c tr o p h o r e s is , 45 p ro tein
lo c i in m u scle, liv e r an d e y e t is s u e s w ere exam ined.
Population Estim ates
Population estim ates of cu tth ro a t, bull {S a lv elin u s c o n flu en tu s),
and brook tr o u t (S. fon tin alis) w ere made in the summer and fall of
1985 and 1986; sp r in g estim ates w ere made in sectio n s I and II in
1985.
Population estim ates w ere calcu lated u sin g Chapman’s
m odification of th e P eterson mark and recap tu re tech n iq u e (Ricker
1975):
(M+l) (C+l)
_ N
(R+D
M=
C =
R =
N =
number of
number of
number of
population
fis h marked
fis h captured
fis h recaptured
estim ate
B ecause low w ater co n d u ctiv ity made e lec tr o fish in g in efficien t,
an gling was u sed to collect fis h fo r m arking, and reca p tu re counts
w ere made by sn ork elin g.
Trout w ere ca u g h t with d ry or subm erged
b a rb less flie s and landed u sin g a net.
Each tro u t w as m easured to
th e n e a r est millimeter, w eighed to th e n ea rest gram, and sexed (w hen
p o ssib le).
Scale sam ples w ere co llected from below and slig h tly
p osterior to th e d orsal fin for age determ ination.
100 mm w ere marked.
T rout lon ger than
Two size g rou p s (100-200 mm and 300-400 mm)
w ere marked w ith fin g er lin g ta g s and two (200-300 mm and 400+ mm)
w ith ty p e FD-68B Floy anchor ta g s.
I u sed d iffe re n t ta g colors for
9
each siz e group and d iffe re n t color com binations for each population
estim ate, allow ing id en tification o f tr o u t size and period of marking.
Marked fis h w ere released at or near th e site of cap tu re.
Marking
ru n s w ere rep eated u n til a 20% or g rea ter recap tu re rate was
reached.
S n o rk el-reca p tu re cou n ts w ere perform ed by a tw o -p erso n crew;
one in th e w ater cou n tin g marked and unmarked fish and one on th e
bank record in g data.
1.
To in su re accu rate snorkel counts:
Only tr o u t o v er 100 mm w ere counted and co u n ts were
made at m id-day w hen sk ie s w ere clear.
2.
A 6.3 mm neoprene d ry s u it was u sed to extend
th e time th e sn ork eler could com fortably sp en d in
th e w ater un d er a v a r ie ty o f conditions.
3.
Snorkel ob serv a tio n s w ere made w ith th e o b se r v e r moving
slow ly upstream along th e sh allow est stream ed g e. To
avoid d istu rb in g tro u t, th e y w ere cou n ted from th e base
of pools and ru n s w h en ever possib le.
*
Montana Departm ent of Fish, Wildlife, and Parks p erso n n el helped
e lec tr o fish sectio n I in summer 1985 and sectio n s I, II, & III in fall
1986.
E lectrofish in g w as u sed to co llect supplem entary data on bull
tro u t and ju v en ile tro u t of all sp ecies.
Snorkel co u n ts w ere su b stitu te d fo r population estim ates in late
fall and w inter.
Cold tem p eratures d u rin g th ese p erio d s made
marking tr o u t d ifficu lt.
Daytime sn o rk el cou n ts w ere condu cted in
section IV on October 29, 1985, in se c tio n s I and II on February 10
and 11, 1986 and, in sec tio n s II and III on January 9 and February
22, 1987.
Winter nighttim e co u n ts (u sin g an underw ater fla sh lig h t)
w ere perform ed on F ebruary 10, 1986 and January 9, 1987.
Water
10
tem p era tu re, a ir tem p era tu re, p h a se o f moon, estim a ted d isc h a r g e and
ic e co n d itio n w as r e c o r d e d fo r ea ch w in ter cou n t.
Creel C ensus
A c re e l c e n su s w as condu cted from April 13th to October 31, 1985
and from April 15 to Septem ber 30, 1986.
A creel clerk station ed at
B eeskove Creek (F igu re I) con d u cted person al in terv iew s from 7:00 am
to 7:00 pm on 10 random ly sele c te d d a y s of each month.
w as stra tified into 5 w eekend d ays and 5 w eek days.
The sample
A ngling location,
size of p arty, an gler resid e n c e , h ou rs fish e d , fish in g method, and
'
catch com position w ere recorded (Table 24, Appendix A).
Angling
location was a ssig n e d to one of th ree areas: B eeskove Creek upstream
to Franklin B ridge, Franklin B ridge upstream to Porcupine Creek, and
Porcupine Creek to th e headw aters (F igure I).
B ooklets w ere
available to a n g le r s for record in g sp e c ie s , size, location and tag
num bers of tro u t cau gh t.
A ccess to th e creek is lim ited to a 9.7 km
trail w hich facilitated accu rate creel cou n ts.
Supplem entary creel
inform ation was collected from a v o lu n teer creel su r v e y .
Data
collection forms w ere provid ed at B eeskove Creek and w ere design ed
to en cou rage p articip ation and accu ra cy (Table 24, A ppendix A).
Estim ated fish in g p r e ssu r e and h ou rs fish ed w ere determ ined
u sin g th e method s u g g e ste d by Johnson and W rablewski (1972).
Estim ates and error w ere calculated from a sea so n -lo n g sample, rath er
than sh o rter in terv a l sam ples, to in crea se th e accu ra cy of the
estim ate (B est and Boles 1956) and to more clo sely approxim ate a
normal cu rv e (Newhold and Lu 1957).
Confidence in te r v a ls were
11
d eterm in ed u s in g th e fo llo w in g e q u a tio n (Bob M cFarland, MDFW&P
p e r so n a l com m unication):
Cl= s / n (td) (1.96)
s=stand ard deviation o f th e sample
n=number of d ays sampled
td=total d ays estim ated
Estim ates o f total catch and cu tth r o a t/h o u r w ere calculated u sin g
th e method of Neuhold and Lu (1957).
Due to limited fish in g p ressu re
above Porcupine creek , th e two a rea s above Franklin B ridge were
combined for data an a ly sis.
F ish Movement
U pstream - downstream Idaho p ic k e t w eirs w ere placed at the
up per and low er e n d s o f sectio n II (F igure I) from J u ly 21 th rou gh
October 3, 1986.
Weir p an els w ere 0.35 m long and 0.6 m high and
contained 1.9 cm h oles e v e r y 2.5 cm.
One and one half meter le n g th s
of 1.9 cm th in -w alled electrica l m etalic tu b in g w ere pounded into each
hole.
I u sed fiv e p an els on each upstream lead and 0.6 cm hardware
cloth was u sed for downstream lead s.
trap box to th e bank.
All leads w ere an gled from th e
Trap boxes w ere 1.2 by 1.0 m w ith hardware
cloth fu n n el en tra n ces.
Traps w ere ch eck ed and clean ed daily.
m easured, w eigh ed , and tagged .
Each tr o u t trapped was
S cales w ere co llected and th e fish
was r elea sed in th e direction of tra v el.
R ecaptured ta g g e d tro u t from
all sec tio n s w ere also u sed to a s s e s s movement.
12
Water Tem perature and D ischarge
Water tem perature data w ere co llected from April 14 th rou gh
October 22, 1986 and from F ebruary 22 th ro u g h F ebruary 29, 1987
w ith a Taylor 7 -d a y record in g therm ograph in sta lled below B eeskove
Creek (F igure I).
The therm ograph was periodically calibrated u sin g
a laboratory therm om eter.
At o th er location s, w ater tem peratures
w ere m easured w ith a laboratory therm om eter.
Stream d isch a rg e was m easured below B eeskove Creek u sin g a
Price AA c u r re n t m eter ap p lyin g th e method recommended by the
USGS (Buchanan and Somers 1969).
Flows w ere tak en periodically
from J u ly th rou gh October, 1985 and June th ro u g h O ctober, 1986.
Habitat V ariables
An in ter a g e n c y habitat and fis h population stu d y b y th e United
S tates F orest S erv ice Lolo National F o rest and Montana Department of
F ish, Wildlife, and Parks began in 1985 and contin ued th ro u g h 1986.
I u sed th eir m ethodology to fa cilitate com parisons betw een R attlesnake
Creek and o th er region al stream s (P eters 1987).
F orty e q u id ista n t tr a n se c ts, one e v e r y 16.4 m, w ere esta b lish ed
p erp en d icu lar to th e stream flow in each stu d y section .
At each
tr a n se c t, w etted w idth, d epth, bank condition, grad ien t, elevation, and
cover, o th er than pool co v er, w ere m easured.
Depth m easurem ents
w ere tak en at 1 /4 , 1 /2 , and 3 /4 th e stream w idth, and th e average of
th e fou r was calcu lated.
Gradient was m easured w ith a clinom eter
o v er th ree long su b se ctio n s and elev a tio n was determ ined from USGS
13
maps.
The rem aining param eters w ere evalu ated u sin g m ethods adapted
from P latts (1979).
Dominant su b str a te size was id en tified at
0.31 m increm ents along each tr a n se c t (Table I).
S u b stra te
com position for each section was determ ined by a v era g in g th e 0.31 m
o b servation s of all 40 c r o ss sectio n s.
Stream bank condition and pool
cla ssifica tio n w ere m easured according to Platts (1979) (Tables 2 and
3).
Cover, in clu d in g tu rb u len ce, d eb ris, overh an gin g b ru sh , and
bou lders was v isu a lly id en tified and m easured lin early along each
tra n sect.
Habitat variab les w ere stand ard ized for a n a ly sis by
co n v ertin g m easured variab les to ratios of th e total (P eters 1987).
Table I.
C lassification of su b stra te material (Platts 1979).
C lassification
boulder
rubble
gravel
fin e s
Particle diameter
304.8 mm or la rg er ( > 12 in ch es)
76.1 - 304.7 mm ( 3 to 11.9 in ch es)
4.7 - 76.1 mm ( 0.2 to 2.99 in ch es)
4.69 mm or smaller ( < 0.19 in ch es)
14
Table 2.
Numerical ra tin g s u sed to c la ss ify stream bank
environm ent (P latts 1979)
cover*
condition
fo r e st
b ru sh
g r a ss
a b sen t
2.0
1.5
1.0
0.5
excellen t
good
fair
poor
ty p e
2.0
1.5
1.0
0.5
sod,root
b ru sh ,ru b b le
g r a ss,g r a v e l
fin es
♦co v er - ty p e of v eg eta tio n dom inating th e stream banks.
condition - sta b ility o f th e stream bank to w ater flow s.
ty p e - a hab itat ty p e th a t can be a sin g le or com bination
o f factors.
Table 3.
Pool qu ality ratin g criteria (P latts 1979)
D escription
Rating
Maximum pool diam eter ex ceed s a v era g e stream w idth.
Pool is o v e r I m (3.28 ft) in depth or o v er 0.6 m
(1.97 ft) in d ep th w ith abundant fis h cover.
5
Maximum pool diam eter ex ceed s a v era g e stream w idth.
Pool is le s s th an 0.6 m in depth w ith interm ediate
to abu ndan t cover.
4
Maximum pool diam eter is le s s than a v era g e stream
w idth. Pool is o v e r 0.6 m in depth w ith interm ediate
to abu ndan t cover.
3
Maximum, pool diam eter is le s s than a v era g e stream
w idth. Pool is le s s th an 0.6 m in dep th and has
interm ediate to abu ndan t cover.
2
Maximum pool diam eter is le s s th an a v era g e stream
w idth. Pool is le s s th an 0.6 m in d ep th and has no
cover.
I
2.0
1.5
1.0
0.5
15
RESULTS
Population C haracteristics
S p ecies Composition
Four fis h sp e c ie s w ere p r e se n t in th e R attlesnake Creek studysectio n s.
Salmonid sp e c ie s included:
w estslo p e cu tth ro a t, bull, and
brook trou t. . Slimy scu lp in s ( C o ttu s co g n a tu s) w ere also p resen t.
Mountain w h itefish ( Prosopium williamsoni) are p r e se n t in lower
R attlesnake Creek and th e Clark Fork R iver, how ever, th e y w ere not
found in R attlesnake Creek above th e dam.
Based on all 1985 and 1986 sn o rk el co u n ts (N=2574), sp e cie s
com position in th e stu d y area was 83% cu tth ro a t tro u t (N=2129), 10%
bull tr o u t (N= 267), and 7% brook tr o u t (N=178) (F igure 2).
Brook
tro u t w ere not cap tu red in or above sectio n IV and w ere most common
in sectio n I (F igu res 2 and 3).
Bull tr o u t w ere p r e se n t in all sectio n s
w ith th e h ig h e s t num bers found in sectio n IV (F igu res 2 and 3).
Estimated rela tiv e abundance of cu tth ro a t tro u t d ecrea sed from 85% in
1985 to 80% in 1986 (F igu res 2 and 3).
G enotype Determination
W estslope cu tth ro a t tro u t in R attlesnake Creek h ave hyb rid ized
w ith rainbow and Yellow stone cu tth ro a t trou t.
The 1985 High Falls
Creek specim ens w ere 96% w estslo p e cu tth ro a t, 4% rainbow and 2%
16
120
%
O O E 0.0 O
t oc
su 85
su 86
fall 85
Section III
cutthroat
fall 86
w 86
E S bull
I
su 85
su 86
Section IV
l hrnnk
100
ip
OoEooro--^-Oc
1985
1986
TOTALS
cutthroat
Figure 2.
1\\\\1 hull
1985-86
I
I brook
Seasonal species composition and distribution in sections
III, IV, and total species composition on Rattlesnake
Creek', 1985, 1986, and 1987.
Do ——— GO OO 3 O o
17
cutthroat
NWMhull
I Jbrook
100
3o
-
GO
OT) g O o
ifi
120r
spr 85
Li L1
su 85
su 80
fall 85
fall 80
w 87
Section Il
cutthroat
Figure 3.
NXWI hull
IZZl brook
Seasonal species composition and distribution in section I
and 11 of Rattlesnake Creek, 1985, 1986, and 1987.
18
Yellow stone cu tth ro a t trou t, w hile th e 1986 Pilcher Creek sample had a
gen etic m ake-up of 80% w estslo p e cu tth ro a t and 20% rainbow trout
(Table 25, Appendix A). A sig n ifica n tly low er amount o f w estslope
cu tth ro a t tr o u t g en etic material was p r e se n t in th e low er Pilcher
Creek sample (X^=25.554, p-value=,001) in d icating th a t th e two
populations are at le a st p artially rep ro d u ctiv ely iso la ted (Rob Leary,
U n iv e r sity of Montana p erson a l com m unications).
H ybridization betw een rainbow and cu tth roat tr o u t p r e se n ts a
problem o f v isu a l recogn ition (Marnell 1978).
There w as no attem pt to
v isu a lly d istin g u ish h y b rid s in th is stu d y .
Trout Size
’
C utthroat tr o u t sam pled b y a n g lin g ran ged from 101 mm to
460 mm total le n g th (N=1132).
Mean le n g th and w eig h t w ere 236 mm
and 172 g, r e s p e c tiv e ly (Table 4).
G reater effo rt w as expended to
cap tu re small tr o u t in 1986; th er e fo re , mean le n g th and w eigh t for
1986 (226 mm and 152 g) w ere le s s th an in 1985 (257 mm and 210 g).
In th e low er th ree se c tio n s, 20% of cu tth ro a t marked w ere larger than
300 mm; th e la r g e s t (480 mm) was c a u g h t above th e dam and
downstream o f th e stu d y sectio n s.
C utthroat tr o u t a v era g e and
maximum le n g th and w eigh t w ere low er in section IV and in section (I)
th an in th e middle s ite s (Table 4).
Summer size d istrib u tio n for 1985
and 1986 by sectio n is in clu d ed in F ig u res 12 and 13, Appendix B.
Seasonally, a v era g e cu tth ro a t tr o u t le n g th s w ere h ig h e s t during fall
of 1985 w hen few er small tr o u t w ere cap tu red (Table 4).
19
Table 4.
Comparison of cu tth roat (Ct), brook and bull tro u t len g th s
(mm) and w eigh ts (g) by stream section du rin g summer
(su ) and fall in R attlesnake Creek, 1985 and 1986.
Section
Season
Section I
Su
Ct
Brook
Bull
Number
1985
1986
Mean len g th (range)
1985
1986
Mean w eight
1985 1986
74
34
27
106
19
0
221 (104-452)
158 (104-264)
193 (104-467)
220 (129-426)
189 (145-232)
159
54
141
145
78
-
Ct
Brook
Bull
12
I
0
52
30
5
348 (165-432)
188 (188)
-
247 (120-425)
150 (108-207)
275 (104-478)
435
41
-
228
35
382
Section II
Su
Ct
Brook
Bull
59
9
0
104
13
4
269 (119-417)
180 (130-234)
-
244 (115-441)
190 (145-309)
327 (207-535)
231
68
-
212
79
508
Ct
Brook
BuU
26
0
0
92
14
33
338 (213-450)
-
216 (101-435)
177 (106-233)
253 (102-675)
408
-
143
65
305
Section III
Su
Ct
Brook
Bull
54
3
0
108
10
2
300 (150-432)
145 (132-152)
-
231 (107-460)
196 (157-251)
302 (102-675)
340
23
-
161
91
305
25
3
I
96
29
17
323 (208-417)
229 (213-246)
358 (358)
219 (103-417)
185 (104-257)
244 (109-440)
290
141
452
135
70
168
Fall
Fall
Fall
Ct
Brook
Bull
Section IV
Su
Ct
BuU
150
2
174
13
224 (127-330)
210 (208-211)
215 (119-400)
250 (190-365)
113
133
107
159
Totals Ct
Brook
Bull
400
50
30
732
115
74
257 (104-452)
170 (104-264)
208 (104-467)
226 (101-460)
177 (104-309)
257 (102-675)
210
60
151
152
64
264
1985-86 Total
Ct
Brook
Bull
1132
143
102
236
175
241
172
63
199
20
Growth, as determ ined from reca p tu res, ranged from 106.5 mm/
year for 100-200 mm tr o u t to 18.7 m m /year for tro u t > 400 mm (Table
5).
S cales for 1985 w ere read b y Don P eters, Montana Department of
Fish, Wildlife, and Parks (F ig u res 14 and 15, Appendix B).
The low est
grow th ra tes w ere from sectio n IV w hich is in th e u p p er drainage
w here low er w ater tem p eratures occur.
Brook tro u t ran ged in total le n g th from 104 mm to 309 mm
(N=143).
A verage le n g th and w eig h t w ere 175 mm and 63 g,
r e s p e c tiv e ly (Table 4).
N in e ty -se v en p e r ce n t o f th e brook trout
cap tu red w ere < 300 mm total len g th .
Total le n g th of bull tro u t sampled in R attlesnake Creek ranged
from 102 mm to 667 mm (Table 4).
average w eigh t was 231 g.
A verage le n g th w as 241 mm and
T w en ty -fiv e p ercen t o f all bull trout
collected in th e fall of 1986 (N=55) w ere more than 300 mm total
len g th .
The la r g e s t bull tr o u t trap p ed was 711.2 mm total
le n g th and w eighed 3266 g.
Bull and brook tro u t reca p tu re ra tes
w ere too low to determ ine grow th.
Population Abundance
The h ook ran d -lin e mark, sn o rk el recap tu re m ethodology was
e ffic ie n t a t estim ating tr o u t pop ulations (Table 6).
Marking took
approxim ately 8 d ays sp read o v er an a v era g e of 26 d a y s.
Angling
marking ru n s w ere more e ffic ie n t w hen condu cted e v e r y oth er day or
early in th e day before an glin g p r e ssu r e in creased .
Overall
m ark /recap tu re e ffic ie n c ie s for cu tth ro a t, bull, and brook trout
21
Table 5.
Table 6.
Mean Growth ra tes of cu tth ro a t trou t determ ined from
recap tu re m easurem ents, 1985 and 1986.
Size
(mm)
Number
mm/year
100-200
5
106.5
200-300
35
45.9
300-400
35
32.0
400+
10
18.7
Summer and fall m ark /recap tu re effic ie n c ies (%) in
R attlesnake Creek, 1985 and 1986.
Section I
Su
Fall
Section II
Su
Fall
Section III S ection IV
Su
Fall
Su
Mean
efficien cy
1985
All CT
100-200
300+
58
51
81
51
36
74
42
0
65
35
36
35
60
27
86
45
42
100
All Bull
All Brook
11
13
All CT
100-300
300+
43
44
43
39
31
53
44
37
61
26
16
57
34
33
40
35
23
89
51
50
60
44
34
64
All Bull
All Brook
—
20
7
50
0
3
0
50
20
18
10
46
-
41
12
Year
Size
(mm)
26
50
50
50
22
22
w ere 44%, 41%, and 12%, r e sp e c tiv e ly (Table 6).
M ark/recapture effic ie n c ies
for cu tth roat tro u t > 300 mm a v era g ed 64% w hich was sig n ifica n tly
h igh er th an th e m ark /recap tu re e ffic ie n c ie s for cu tth ro a t tro u t < 300
mm (34%) (p=0.003).
Estim ates fo r brook and cu tth ro a t tro u t < 300 mm
should be regard ed w ith caution.
Estimated cu tth ro a t tr o u t abundance (summer day 1985 and 1986)
was g r e a te st in sectio n I, followed b y sectio n s IV, III, and II (F igu res
4 and 5).
A verage number of cu tth ro a t in section I, II, III and IV
(0.61 km each) w as 409, 215, 260, and 308, r e sp e c tiv e ly (Tables 26-33,
Appendix A).
Section II followed b y sec tio n s III, I, and IV had the
g r e a te st abundance o f cu tth ro a t tr o u t > 300 mm total len g th . In
general, th e sec tio n s w ith th e g r e a te s t abundance of cu tth ro a t tro u t
contained th e low est num bers of tr o u t > 300 mm.
A verage fall daytime
estim ates in d ica tes th a t sectio n III contain ed th e g r e a te st number of
cu tth roat tro u t (170) followed b y sec tio n s II (169) and I (128).
Fall
estim ates w ere not com pleted in sectio n IV.
Bull tr o u t w ere fa irly e v e n ly d istrib u ted among th e four sectio n s
(F igu res 2 and 3).
S ection I contained th e h ig h e st number of brook
tro u t (average HO) (F igu res 2 and 3, Tables 26-33, A ppendix A).
Estim ates o f brook and bull tro u t abundance w ere som etim es not
p o ssib le due to low num bers marked or recaptured .
Seasonal flu ctu a tio n s in cu tth ro a t tro u t population estim ates w ere
g r e a te st for th e 100-200 mm size group (F igu res 4 & 5).
than 200 mm show ed few er flu ctu a tio n s.
Trout lon ger
Annual cu tth ro a t trou t
m
23
Q.<B ^I-O 3
— ~ U )
S ection I
-> ® CT 3 C Z
164
Su 1985
Fall 1986
Fall 1986
EZ3 CT 2 0 0 -3 0 0 mm
CT 1 0 0 -2 0 0 mm
EHB CT 3 0 0 - 4 0 0
Su 1986
mm
ES3 CT 400+ mm
(DCr 3 C: Z
CLCD — CD 3 ——CO m
400
300
200
100
0
Su 1985
Figure 4.
Fall 1985
Su 1986
CT 1 0 0 -2 0 0 mm
EZ2 CT 2 0 0 -3 0 0 mm
CT 3 0 0 - 4 0 0 mm
E 53 CT 400+ mm
Fall 1986
Estimated number of cutthroat trout by size class, season,
and section (0.6 km) in Rattlesnake Creek. Confidence
intervals shown in Tables 28, 29, 32, and 33, Appendix A.
o cr 3 c z
q .<
d
^
od
3 — «-►co m
24
Su 1985
■ i
Fall 1986
Su 1986
Fall 1986
CT 1 0 0 -2 0 0 mm
E 22 CT 2 0 0 -3 0 0 mm
CT 3 0 0 - 4 0 0 mm
^ 3
CT 400+ mm
200
150
<d o" 3 c z
«-*•Cd 3 —
250
q .0
Co rn
300
r
100
50
0
Su 1986
CT 1 0 0 -2 0 0 mm
Figure 5.
Fall 1985
Su 1986
E 23 CT 2 0 0 -3 0 0 mm
EHBCT
Fall 1986
3 0 0 -4 0 0 mm
Estimated number of cutthroat trout by size class, season,
and section (0.6 km), in Rattlesnake Creek. Confidence
intervals shown in Tables 30, 31, 34, and 35, Appendix A.
25
population flu ctu a tio n s, from 1985 to 1986, w ere also se e n mainly in
th e 100-200 mm s iz e -c la s s (Table 7 & 8).
In summer, confid en ce
in ter v a ls for th e 1985 and 1986 estim ates o f cu tth roat tro u t > 200 mm
all overlap while th o se for tro u t < 200 mm do not overlap .
In fall, a
similar b u t more variable p attern was noted (Table 8).
Creel C ensus
A ngler Hours and P ressu re
In 1985 and 1986, an glin g p r e ssu r e was low and ca tch ra tes w ere
high on R attlesnake Creek.
In 1985, an estim ated 457 a n g lers fish ed
th e stream du rin g th e 25-w eek c e n su s period compared to 254 in 1986
(Table 9).
Estim ated h ou rs fish e d also d ecreased from 1184.5 in 1985
to 658.6 in 1986.
During th e same period catch ra tes in crea sed
s lig h tly from 3.0 c u tth r o a t/h o u r to 3.4 cu tth ro a t/h o u r.
A nglers w ere not e v en ly d istrib u ted along R attlesnake Creek.
S ix ty -fo u r p e r ce n t of an glin g occu rred in th e low er area betw een
B eeskove Creek and Franklin B ridge, while 36% fish e d from Franklin
B ridge to Porcupine Creek (F ig u res I & 6).
A lthough cu tth roat tro u t
w ere on th e avera g e la rg er in th e more h eavily fish e d area (Table 4),
catch r a te s w ere approxim ately 0.5 cu tth r o a t/h o u r le s s below Franklin
B ridge (2.6 c u tth r o a t/h o u r) than above Franklin B ridge (3.0
cu tth ro a t/h o u r).
Weekday and w eekend an gler u se w as not eq u ally distributed;
1985-86 w eek day p r e ssu r e av era g ed 1.4 a n g le r s/d a y w hile w eek en d holiday p r e ssu r e a v era g ed 3.0 a n g le r s/d a y .
Estimated an gler use
26
Table 7.
Comparison of 1985 and 1986 summer daytime cutthroat
tro u t population estim ates for four sectio n s of
R attlesnake Creek. C onfidence in terv a ls are shown
in p a ren th eses.
Size
(mm)
Section I
1985 1986
All
597 221
(176)(45)
138
(36)
276
(62)
150
(51)
369
(97)
374 385
(68) (59)
100-200
506 154
(195)(51)
70
(45)
238
(114)
20
(14)
250
(119)
251 206
(103) (52)
200-300
53 50
(30)(12)
53
(26)
57
(18)
76
(45)
98
(32)
161 159
(30) (31)
300-400
21 25
(15)(16)
33
(H )
31
(6)
39
(15)
33
(16)
8
20
(4) (10)
9
(4)
8
(4)
7
(5)
7
(5)
400+
Table 8.
7
(5)
6
(3)
Section II
1985
1986
Section I III
1986
1985
Section IV
1985 1986
0
Comparison of 1985 and 1986 fall daytime cu tth ro a t trout
population estim ates in th ree sectio n s of R attlesnake Creek.
C onfidence in terv a ls are show n in p a ren th eses.
Size
(mm)
S ection I
1985 1986
Section II
1985
1986
Section III
1985
1986
All
43
(25)
212
(77)
71
(36)
267
(83)
62
(23)
277
(70)
7
(8)
102
(55)
0
-
290
(210)
0
165
(75)
200-300
9
(9)
107
(88)
59
(75)
50
(25)
41
(30)
115
(65)
300-400
17
(9)
17
(5)
27
(13)
31
(10)
25
(10)
24
(7)
400+
2
(2)
7
(6)
12
(6)
6
(4)
4
(3)
6
(4)
100-200
0
-
27
Table 9.
Period
Total estim ated a n g le r s, hours fish ed and cu tth roat (Ct)
cau gh t per hour, R attlesnake Creek, April th rou gh
Septem ber, 1985 and 1986.
# d ays sampled
(# d ays e s t .)
Estimated a n g lers
(95% Cl)
1985
Weekday
Weekend
Total
28 (118)
32 (51)
60 (169)
123 (44.5)
334 (117.9)
457 (162.4)
645.5
539.1
1184.5
(353.4)
(198.5)
(588.2)
3.02
1986
Weekday
Weekend
Total
23 (128)
31 (55)
54 (183)
64 (25.8)
190 (107.0)
254 (132.8)
316.2
342.4
658.6
(309.9)
(166.9)
(512.5)
3.37
114 (353)
711 (295.2)
TOTAL
Estimated hours
(95% Cl)
1843.1 (1119.4)
C t/hr
-
T
0
t
a
1
e
s
t
I
m
a
t
e
d
a
n
ro
OO
?
6
r
8
W e ek d a y
W e ek en d
B e e s k o v e Cr. - F rank lin Br.
1985
Figure 6.
W eek d a y
W eek en d
F ranklin Br. - P o rcu p in e Cr.
2 2 3 1986
Estimated number of anglers in two areas of Rattlesnake Creek
during weekdays and weekend days, 1985 and 1986.
29
peaked in mid-summer.
In 1985, Ju ly was th e h ig h est an gler use
month (128) followed by A ugu st (78), June (77), May (70), Septem ber
(53), and April (50).
In 1986, estim ated angler u se was h ig h est in
A ugu st (HO) follow ed by July (88), June (59), May (38), Septem ber
(22), and April (11).
(22%) u sed lu res.
Most an g lers u sed flie s (78%); th e remainder
A ngler r esid e n c y w as not determ ined due to
in su ffic ie n t data.
Catch and Catch Comnosition
C utthroat tro u t made up th e g r e a te st proportion o f th e an glers'
catch.
During th e 12 month c e n su s period, 879 (92%) cu tth roat, 83
(5%) brook, and 29 (3%) bull tro u t w ere rep orted ca u g h t and released .
Compared to 1985 and 1986 estim ated sp e cie s abundance (Figure 3),
cu tth ro at tro u t (> 100 mm) w ere ca u g h t in high er proportion s than
th eir relative abundance (79.5%).
The total estim ated cu tth ro a t tro u t catch declined from 3,577 in
1985 to 2,042 in 1986, paralleling th e d ecrea se in a n gler u se (Table 9).
The catchable (> 100 mm) cu tth roat population in areas open to
fish in g (sectio n s III and IV) show ed no in crea sin g or d ecreasin g
tren d betw een summer 1985 and 1986 (Table 7).
Total brook and bull
tro u t catch could not be estim ated b eca u se of small sample size.
R ecapture Rates
Tag retu rn data in d icate th at e v en w ith rela tiv ely low fish in g
p r e ssu r e , 22% of th e cu tth roa t tro u t marked w ere recap tu red (Table
10).
R ecapture rate in crea sed w ith size of fish .
C utthroat tro u t over
30
Table 10.
Size
Number and size d istrib u tio n of cutthroat tr o u t marked
and recap tu red by an glin g in 1985 and 1986.
# Marked
# Recapt.
(X)
# Recapt.
3+ times
Max. # recapt.
per fis h /y r .
100-200
458
38 ( 8)
I
3
200-300
396
93 (24)
19
4
300-400
159
77 (48)
25
5
31
21 (68)
11
12
1044
229 (22)
400+
Total
31
400 mm had th e h ig h e st recapture rate (68%) and th e g r ea test
in cid en ce of recap tu re for a sin g le tro u t (12 tim es in 12 months).
Only 8% of th e 100-200 mm cu tth ro a t tro u t w ere recap tu red and the
maximum recap tu re rate was th ree tim es in 12 months.
Movement
Based on trap p in g and an gler reca p tu re, cu tth ro a t tro u t
movements w ere small and direction o f movement was variable.
Of
1,044 cu tth roat tro u t ta g g e d , 21% (N=222) w ere rep orted caught.
Twelve p e r ce n t (N=26) of th e se fish had moved out o f th e section
w here th e y w ere ta g g ed .
Nine cu tth ro a t tro u t moved upstream and 17
moved downstream (Table 11); direction of movement w as not
sig n ifica n tly d iffe re n t (p=0.17).
Downstream movement was sig n ifica n t
for cu tth roat tro u t < 300 mm (p=.016) b u t additional trap p in g data
s u g g e s t th is is not a w idespread tren d .
Only 3% (N=7) of the
recap tu red tr o u t moved more than 1.6 km; six of th e se v e n were le s s
than 300 mm total len g th .
Bull and brook tro u t movement could not
be determ ined from tag retu rn data.
F ifty -s ix cu tth roat, 28 brook, and 30 bull tro u t w ere captured in
tra p s above and below section II betw een July 21 and October 3, 1986
(Table 12).
Mean total le n g th s for cu tth ro a t, brook, and bull trout
w ere 167.9, 135.5, and 364.0 mm, r e sp e c tiv e ly . S ix ty -fiv e tro u t moved
S
upstream and 49 moved downstream , b u t direction of movement was
not sig n ifica n tly d iffe re n t (p=0.16).
T w en ty -sev en cu tth ro a t < 300 mm
moved upstream and 24 moved downstream; directional movement
32
Table 11.
Size
(mm)
Movement of cu tth ro a t tro u t based on tag retu r n s, 1985
and 1986. Only movement out of section ta g g ed is
recorded.
Number
marked
Number
recaptured
Number
moved
Direction moved
up
down
100-200
458
38
3
0
3
200-300
396
93
11
2
9
300-400
159
70
6
4
2
31
21
6
3
3
Total
1044
222
26
9
17
Table 12.
Number, size , and direction o f tra v el of tr o u t trapped in
R attlesnake Creek, 1986.
Sp ecies
Number
400+
A verage
len gth
< 300 mm
(X)
Movement
direction
up
down
Ct
56
167.9
51
(91)
32
24
Brook
28
135.5
28 (100)
17
11
Bull
30
364.0
10
16
14
Total
114
65
49
(33)
33
for th e sm aller cu tth ro a t tr o u t was also not sig n ifica n t (p=0.78) (Table
13).
Most cu tth ro a t and all brook tr o u t trapp ed w ere < 300 mm total
f
le n g th (F igure I). However, only 33% of th e bull tr o u t trapped w ere
< 300 mm (F igure I),
Much of th e bull tro u t movement was associated
w ith spaw ning; a t le a st 38% w ere spaw ning adults.
Overall, 74 tr o u t (all sp e cie s) w ere docum ented m oving upstream
and 66 downstream (Tables 11 & 12).
Trout show ed no sig n ifica n t
o
p referen ce for direction o f movement (X =0.35, p=0.55).
The la r g est
record ed movement was 16.9 km downstream.
Habitat
Habitat C h aracteristics
Habitat c riter ia w ere m easured in Septem ber 1986 (Table 14).
Mean g rad ien t for th e fou r stu d y sec tio n s on R attlesnake Creek was
1.77%.
S ection s I and IV had g ra d ien ts of 1.6% and 1.5% and sectio n s
II and III, both w ith long riffle a rea s, had a 2.0% gradient.
Stream w idth (average 10.9 m) and dep th (average 0.32 m) were
similar betw een sectio n s.
S u b stra te com position va ried little betw een sec tio n s (Table 14).
Overall, su b str a te com position c o n sisted of 2.5% fin e s, 16% gravel,
55.5% ru b b le, and 26% bou lders.
Good spaw ning g ra v el w as available
th ro u g h o u t th e R attlesnake Creek drainage.
P ool-riffle ratio in stu d y sec tio n s was 33:67.
o f all pools in R attlesnake Creek w ere c la ss 4 or 5.
F o r ty -six p ercen t
Section I had 77%
34
Table 13.
Size
(mm)
Directional movement, by size c la ss, of cu tth ro a t trout
trapp ed in R attlesnake Creek, July 21- October 3, 1986.
Number
Moved
Upstream
Downstream
100-200
41
25
16
200-300
10
2
8
300-400
5
5
0
400+
0
0
0
Total
56
32
24
35
Q- ®TDTDffl ^ H -« ® CJ 3 C Z
20 r
100 125 150 176 200 226 260 276 300 326 360 376 400
Q. ® "OTDCD-> —< -I ® CJ 3 C Z
Cutthroat Trout Length (mm)
100 126 160 176 200 226 260 276 3 0 0 326 36 0 376 400
© CT3 C 2
Brook Trout Length (mm)
Si--------------------------------- ---------
T
r
a
D
P
e
d
Bull Trout Length (mm)
Figure 7 .
Length frequencies of cutthroat, brook, and bull trout
trapped in Rattlesnake Creek between July 21 and
October 3, 1986.
36
Table 14.
Habitat data collected on R attlesnake Creek, Septem ber,
1986.
Type
Section II
Section III
40
60
37
63
35
65
20
80
11
12
30
13
34
32
23
3
10
32
7
23
19
28
23
12
28
14
22
24
Boulder
Rubble
Gravel
Fines
29
48
21
2
28
65
6
I
29
57
12
2
18
52
25
05
X bank &
instream
cover
32
O
27
15
A verage
w idth (m)
11
11
10
12
A verage
depth (m)
0.34
0.24
0.31
0.37
A verage
grad ien t (X)
1.6
2.0
2.0
1.5
Excellent
Good
Fair
Poor
97
3
0
0
96
4
0
0
98
I
I
0
97
2
I
0
Elevation
1187
1219
1225
1398
X pools
X riffle
Section I
Section I
Pool c la ss X
I
II
III
IV
V
S u b strate X
Banks
(m)
37
h igh c la ss pools (3+) compared to 45% in sectio n II.
Instream and
bank co v er was available on approxim ately 25% of th e stream.
Tem perature and D ischarge
Water tem p eratu res in R attlesnake Creek, 1985-86, ran ged from
16.7°C to - 2 .2 0C.
Tem peratures below 0°C may be in error.
Monthly
w ater tem perature du rin g th e stu d y ran ged from 0°C to 11.4°C
(F igure 8) compared to 1958-65 minimum and maximum tem peratures of
16.7°C and 0°C (Aagaard 1969).
Stream d isch arge m easured in 1985 and 1986 ra n g ed from 10.2
c fs to 113 c fs (F igure 8).
High w ater d isch a rg e could not be
m easured w ith available equipm ent.
(F igure 8).
Flows in 1985 and 1986 varied
In 1985, summer flow s w ere lower th an in 1986, how ever,
late season rain s in 1985 in crea sed fa ll d isch a rg e (F igu re 8).
Habitat U se and Behavior
From sp rin g 1985 to w inter 1987, 27 sn ork el co u n ts of tro u t in
R attlesnake Creek w ere made.
S ev era l additional sn o rk el o b serv a tio n s
w ere made th ro u g h o u t th e year.
Most habitat u se and behavior data
collected du rin g sn ork elin g w ere qu alitative.
Spring 1985-Day
Few fis h w ere catchable in th e sp rin g .
Only fo u rtee n cutthroat
and one bull tr o u t w ere marked in sec tio n s I and II betw een March 26
and April 8, 1985 (Table 15).
len g th .
All fis h w ere lon ger th an 300 mm total
A sn ork el recap tu re run w as perform ed on April 9, 1985.
I?n
5
'ISCHARCE (i
S
CK
g
g
§
OJ
00
Figure 8.
S t r e a m discharge a n d m e a n t e m p e r a t u r e s taken on
Rattlesnake C r e e k below B e e s k o v e C r e e k from J u n e
t h r o u g h F e b r u a r y 1987.
1985
39
Table 15 .
Sp ecies
Number of cu tth ro a t tro u t marked, cap tu red , and
recap tu red in S ections I and II of R attlesnake Creek,
sp rin g 1985.
Size
(mm)
C utthroat
100-200
200-300
300-400
400+
Total
Bull
400+
Section I
M*
C
R
Section II
M
C R
0
0
8
2
10
0
I
22
2
25
0
0
4
2
6
0
0
3
I
4
0
0
6
0
6
0
0
2
0
2
I
I
I
0
I
0
* M=marked C=Captured R=recaptured
40
Water tem perature was 4.4 °C.
Few cu tth ro a t w ere o b serv ed in
section I (N=25) or section II (N=6). (Table 15).
All cu tth ro a t trout,
excep t one, w ere larger than 300 mm and all bull tro u t (N=2) were
larger than 400 mm (Table 15).
Trout mainly occu pied pools and ru n s, exhibited neutral rheotaxis
(moved in all d irection s relative to th e cu rren t), and moved in a
"milling" fashion.
Large trou t g en era lly ignored th e d iv er and no
fish w ere o b serv ed feed in g .
During marking ru n s, how ever, trout
s lu g g ish ly took both d ry and w et flies.
Hierarchical or territorial
social str u c tu r e s w ere not ob serv ed .
Summer 1985 - Day
Summer sn ork elin g was condu cted from June 4 th ro u g h A ugust
25.
Water tem p eratures ranged from 7.8 to 16.7 0C.
sec tio n s, 649 cu tth roat trou t w ere o b serv ed .
In th e four stu d y
E ig h ty -e ig h t p ercen t of
th e cu tth ro a t w ere < 300 mm total le n g th (Tables 26-29, Appendix A)
and 51% of th e se w ere o b serv ed in sectio n I.
The s h ift from a
dominance of large ad u lt cu tth ro a t tro u t in sp rin g to smaller
cu tth roat in summer occu rred sometime during high w ater.
B etw een June 4 and July 2 adu lt tro u t a g g reg a ted at th e tail
portion o f h igh c la ss pools (4 and 5) and in runs w here spawning
gra v el was available.
was ob served .
13.8 c fs.
A g g ressiv e behavior associated w ith spawning
By m id-July, flow s in R attlesnake Creek dropped to
Adult cu tth roat tro u t moved o u t of low v e lo c ity pools and
ru n s into riffle areas.
Trout a c tiv ity during th is period appeared to
be a sso ciated w ith feed in g.
41
Sm all-sized cu tth roat tro u t (< 300 mm) occupied pocketw ater
w ithin riffle areas th rou gh ou t th e summer.
They w ere ob serv ed
immediately downstream of bou lders, d eb ris, or in oth er reg io n s of
red uced cu rren t.
Small tro u t u su a lly position ed th em selv es
downstream from larger tro u t in d icatin g a hierarchical^ size -r e la te d
social stru ctu re.
A ctive d rift and su rface feed in g was exhibited b y all cutthroat
trou t o b serv ed .
In d ivid u als maintained rela tiv ely sta tio n a ry positions
close to th e bottom and ad jacen t to fa s t c u rren ts, moving both
laterally and upward to feed and retu rn in g to th eir origin al position.
Some tro u t w ere o b se rv e d feed in g on 2-3 food items d u rin g th e time
of o b servation (approxim ately 1-3 m inutes).
o b serv ed during th is period.
P ositive rheotaxis was
C utthroat tro u t were commonly
o b serv ed in open, un sh aded areas se v e r a l m eters from d eb ris or bank
cover.
Areas w ith m oss-covered su b str a te ( F ontinalis sp p ) were
avoided by cu tth roat b u t not by brook trout.
Summer 1986 - Day and Night
Daytime habitat selection and behavior p attern s o b se rv e d during
summer 1986 w ere similar to th o se d escrib ed for summer 1985.
On
July 28, a nighttim e sn ork el count was perform ed in sectio n I.
Nighttime abundance (94) was similar to daytime abundance (98) (Table
30, Appendix A).
Size d istrib u tion o f cu tth roat tro u t show ed little
variation from day to night.
S everal of th e same location s occupied
during th e day w ere u sed at n ig h t b y th e same or sim ilar-sized
cu tth roat trout.
42
Fall 1985 - Day
A gradual decline in num bers o f cu tth roat tro u t < 200 mm was
o b serv ed in sec tio n s I, II, and III betw een Septem ber 10 and
Septem ber 21, 1985 (marking ru n s).
During th is period minimum
tem p eratures dropped from 6.7° to 1.1° C.
Water tem p eratures,
during sn o rk el co u n ts, ran ged form 2.2 ° C to 5.0 ° C.
Fall cou n ts
of cu tth ro a t tr o u t < 300 mm w ere sig n ifica n tly lower (X =335, p<0.05)
than summer cou n ts (F igu res 9-11).
Only th ree cu tth ro a t trou t <200
mm w ere o b se rv e d in th e th ree sec tio n s snorkeled in fall 1985 .
(F igure 8).
Numbers o f tro u t 300-400 mm flu ctu a ted irreg u la rly while
th o se > 400 mm rem ained v irtu a lly u n ch anged (F ig u res 10 & 11).
A daytime sn ork el cou n t was con d u cted in sectio n IV on October
29, 1985.
Water tem perature was 2.8° C.
Trout in sectio n IV were
smaller th an tro u t in th e oth er sectio n s; only 5% w ere > 300 mm.
Numbers o f 100-200 mm tro u t o b serv ed d ecreased s lig h tly from 80
(summer) to 74 (fall) (F igure 11).
C ontrary to o b serv a tio n s in the
low er th re e sec tio n s, d e n sitie s of 200-300 mm cu tth ro a t tro u t
in creased from 80 (summer) to 147 in fall.
T ran sitions in trout
hab itat selectio n took place betw een A u gu st 4, 1985 (summer snorkel)
and m id-Septem ber (fall marking p eriod).
Tem peratures during th e
period dropped from an average of 7.8°C (low=6.1 °C) to 4.6°C (low
1.1 °C).
A ggregation and a d ecrea se in feed in g a c tiv ity w ere noted.
By October 17, 1985, tr o u t w ere co n cen tra ted in pools.
Several
sp e c ie s and size c la ss e s of tr o u t occu pied th e same pools w ith no
43
SE CT
50
<200
B
50
SECT.
50
Number
SECT
0
Su
85
Figure 9.
Fall
85
Su
86
Fall
86
Number of cutthroat trout <200 mm total length counted
in sections I-III during the day in Rattlesnake Creek,
summer and fall 1985 and 1986.
44
^ CD e r g C Z
Section
Spr 85
Su 85
Fall 85
—— CT 2 0 0 -3 0 0 mm
W 86
—F- CT 3 0 0 -4 0 0 mm
Su 86
Fall 86
CT 400+ mm
<D e r g C Z
Section Il
Su 85
Fall 86
—— CT 2 0 0 -3 0 0 mm
Figure 10.
W 86
Su 86
- F - CT 3 0 0 -4 0 0 mm
Fall 86
W 86
CT 400+ mm
Number of cutthroat trout > 200 mm total length counted
seasonally during the day in sections I and II of
Rattlesnake Creek, 1985 and 1986.
45
Section III
Spr 85
Su 85
Fall 85
—— CT 2 0 0 -3 0 0 mm
W 86
Su 86
—t— CT 3 0 0 -4 0 0 mm
Fall 86
W 87
CT 400+ mm
Section IV
Z
3 E - O (D
Spr 85
Su 85
- S - CT 1 0 0 -2 0 0 mm
Figure 11.
Fall 85
W 86
— - QT 2 0 0 -3 0 0 mm
Su 86
Fall 86
—F- CT 3 0 0 -4 0 0 mm
Number of cutthroat trout > 100 mm total length counted
seasonally during the day in sections I I I and IV of
Rattlesnake Creek, 1985 and 1986.
46
o b se rv e d a g g r e s s iv e in teractio n s. .
Fall 1986 - Day and N ight
In fall 1986, daytime sn ork el co u n ts w ere made in sectio n s I, II,
and III.
Nighttime co u n ts w ere made in sectio n s II and III.
Point
m easurem ents o f w ater tem peratures ran ged from 4.2 ° to 5.0° C (Table
16).
Minimum w ater tem perature, m easured w ith th e therm ograph, was
1.4° C in 1985 compared to 2.8 °C in 1986.
Stream d isch a rg e was
su b sta n tia lly d iffe re n t betw een y ea rs (F igure 8).
C utthroat tr o u t a g g r eg a ted in pools during fall 1986 bu t daytime
num bers of small tr o u t did not d ecrea se as dram atically a s o b serv ed
.
in 1985 (F igure 9, Table 16).
A lthough d ecrea ses w ere not as
pronounced as in 1985, 1986 summer and fa ll counts w ere sig n ifica n tly
o
d iffe re n t (X =55.2, p<0.05).
Day and n ig h t cou n ts va ried b u t w ithout
c o n siste n t tr e n d s (Table 16).
Winter 1985-86 - Day and Night
Three p a tte rn s of ice formation w ere o b serv ed in th e lower th ree
stu d y sec tio n s.
In sectio n I, anchor ice formed in r iffle s while sh elf
ice formed on pools.
Some sh e lf ice formed in sectio n II, how ever
th is sectio n appeared to be in flu en ced b y groundw ater in p u t and
g en erally rem ained ice free.
The su rfa ce of sectio n III fro ze and
snow accum ulated on th e ice.
One nighttim e and fou r daytime sn o rk el cou n ts w ere perform ed
du rin g w inter 1985-86.
Thick mats o f aquatic v eg eta tio n w ere more
47
Table
Size
(mm)
16.
Comparison o f cu tth roat trou t abundance during fall
1985 and 1986 snorkel co u n ts in sectio n s I, II, and III of
R attlesnake Creek. Water tem peratures show n in
p a ren th eses.
Section I
1985 1986
day
day
( 5 * 0 (4.2*C)
Section II
1985
1986
day
d a y /n ig h t
(2*C) (5*C) -
Section III
1985
1986
day
d a y /n ig h t
( 4 * 0 (5*C) -
100-200
3
36
0
26/62
0
38/27
200-300
9
35
5
23/14
13
31/25
300-400
8
10
19
16/15
21
21/12
400+
3
3
7
6 /1
4
6 /3
23
84
31
71/92
38
96/67
Total
48
abundant in w inter th an in sp rin g or summer.
On December 9, 1985, sectio n I was snorkeled betw een 2:00 and
4:00 pm.
S k ies w ere clear and sh e lf ice extended out from banks.
Air and w ater tem p eratures w ere not recorded.
T w en ty -sev en
cu tth roat, 16 brook and 6 bull tr o u t w ere counted (Table 17).
Numbers o f cu tth ro a t tro u t < 300 mm rem ained low, similar to fall
(Table 17).
In December, daytim e abundance o f cu tth roat, brook and bull
tro u t w as h ig h e st in pools (Table 18), w ith a s many a s 17 in one pool.
Three tr o u t (Ct 100-200, Ct 300-400, and bull 300-400 mm) w ere
o b se rv e d ad jacen t to a run in shallow w ater.
r e stin g on th e su b str a te .
f
Two of th e th ree w ere :
All th re e so u g h t cover w hen d istu rb ed .
Trout so u g h t co v er un d er sh e lf ice, in d eb ris, or in subm erged leaf
p iles and w ere gen era lly more e a sily d istu rb ed in w in ter than in
summer.
On F ebruary 11, 1986, another w in ter daytime co u n t was
perform ed in sectio n I from 12:00 to 2:00 pm.
S k ies w ere clear and
air and w ater tem p eratures w ere -7.2°C and O6C, r e sp e c tiv e ly .
Anchor ice w as p r e se n t in riffle a rea s, sh e lf ice exten d ed out from
lo g s, b ou lders and banks, and fra zil ice was su sp en d ed in th e water
column.
F o r ty -six cu tth roat, 14 brook and 6 bull tro u t w ere o b serv ed
(Table 17).
Comparisons w ith total num bers of cu tth ro a t trou t
counted on December 9th show s an in crea se from 27 to 46 (Table 17).
The in crea se occu rred prim arily in th e < 300 mm size c la sse s.
In F ebruary 1986, tro u t w ere co n g reg a ted in pools (Table 18) w ith
49
Table 17.
Summer (su) 1985, fall 1985, and w inter (w) 1985-86
daytime cu tth ro a t tro u t co u n ts and w inter 1985-86
brook and bull trou t co u n ts in Section I of
R attlesnake Creek.
Size
(mm)
C utthroat
Su 1
Fall 2 W 3
Brook
Bull
W4
W3
W4
W3
W4
100-200
306
3
5
16
10
13
0
I
200-300
19
9
6
16
6
I
0
2
300-400
19
8
14
10
0
0
I
0
4
3
2
4
0
0
5
3
348
23
27
46
16
14
6
6
400+
Total
1
2
3
4
=
=
=
=
8 /4 /8 5
10/29/85
12/9 /8 5
2 /1 1 /8 6
50
Table
18.
Number of cu tth roat, brook and bull tro u t counted,
by habitat ty p e, in R attlesnake Creek, 1985 and 1986.
Pool
Run
Riffle
I
34
12
3
12/11/85
II
40
33
5
2 /1 0 /8 6
II
48
13
3
2 /1 0 /8 6
Night
II
74
26
12
2 /1 1 /8 6
I
62
16
15
1 /9 /8 7
II
78
31
4
1 /9 /8 7
Night
II
73
28
10
409
159
52
Date
12/9/85
Total
Section
51
as many as 36 in a sin g le pool.
All tr o u t in riffle areas were
< 200 mm excep t one w hich was 200-300 mm.
S everal tr o u t u sed sh e lf
ice for cover; none w ere o b serv ed in areas with anchor ice.
On December 11, 1985, sectio n II w as snorkeled du rin g mid-day.
S k ies w ere partially clou d y bu t v is ib ility was good.
Frazil ice was
p r e se n t and sh e lf ice extended out from ban ks, bou ld ers, and logs.
Air and w ater tem p eratures w ere - 1 2 °C and V C , r e sp e c tiv e ly .
F ifty -
e ig h t cu tth roat, 4 brook and 16 bull tr o u t w ere o b se rv e d (Table 19).
A lthough th e num bers o f cu tth ro a t < 200 mm in crea sed o v er fall , th e
w inter cou n t of cu tth ro a t < 300 mm (N=24) was almost half th e summercou n t (N=46).
Again, most tr o u t w ere o b serv ed in pools and r u n s (Table 18).
Trout p er pool ran ged from 2 to 17.
g en erally contained more trout.
L arger, h igh er q u ality pools
One exceptionally h ig h quality run
(long w ith abundant co v er and p o ssib le in flu en ces from groundw ater
rech arge) contain ed 32 trou t.
Five tr o u t w ere o b se rv e d in
p ocketw ater w ithin a long riffle area.
One of th e fiv e was a 100-200
mm bull tr o u t th a t w as w edged betw een two cob b les (in th e su b stra te)
w ith only th e tail v isib le .
u n til tou ch ed .
su b str a te .
The bull tr o u t did not flee from the d iver
Two o th er bull tr o u t w ere o b serv ed r e stin g on th e
All o th er tro u t w ere ea sily d istu rb ed .
S cu lp in s were
noted and a v e r y large bull tro u t (estim ated 700 mm) was ob served .
On F ebruary 10, 1986, Section II was sn orkled betw een 1:15 and 3:20
pm.
S k ies w ere 80% o v erca st.
p r e se n t around a few bou lders.
L ighting was good.
S h elf ice was
Thick mats of moss w ere ob serv ed
52
Table 19.
Summer (su ), fall (f), and w inter (w) day and nigh t
cu tth roat cou n ts for sectio n II of R attlesnake Creek,
1985. Also in clu d es F ebruary 10, 1986 daytime (W) and
nighttim e (N) cou n ts for brook and bull trout.
C utthroat
Size
(mm)
Brook
W3
W/N4
2/3
2
6/3
0
1/2
4
4/6
17/24
0
0 /0
3
3/6
9
4/11
0
0 /0
7
2/2
58
46/88
4
3/5
16
15/17
Su1
F2
W3
W/N4
W3
100-200
24
0
17
16/35
4
200-300
22
5
7
9/18
300-400
22
19
25
400+
9
7
Total
77
31
1
2
3
4
= 7 /1 0 /8 5
= 10/17/85
= 12/11/85
= 2 /1 0 /8 6
Bull
W/N4
.53
th rou gh ou t th e section .
1.7 °C, r e sp e c tiv e ly .
Air and w ater tem peratures w ere -1.1 °C and
F o r ty -six cu tth ro a t, 3 brook and 15 bull trout
w ere o b se rv e d (Table 19).
Trout num bers w ere similar to those
cou n ted in th e same sectio n on December 11, 1985 (Table 27,
Appendix A).
S e v e n ty -fiv e p e r ce n t of th e tr o u t w ere in pools (Table 18) and
each pool contain ed 4-13 trou t.
mm total le n g th .
un der moss.
Trout in th e riffle a rea s w ere 100-200
One tro u t was o b se rv e d r e stin g on th e su b stra te
All o th er tro u t w ere alert.
marks .near th eir tail.
Two fish had fr e sh gash
Bull tro u t occu pied position s clo se r to the
su b str a te th an cu tth ro a t tro u t and inh abited high c la ss pools with
abundant cover.
A sin g le cu tth ro a t tro u t was o b se rv e d feed in g .
A n ig h t dive was perform ed in sectio n II on F ebruary 10, 1986
b egin n in g at 7:30 pm.
The moon was not v isib le.
was -6.7 °C; w ater tem perature was 0.6 0C.
Air tem perature
Two bull tr o u t w ere
attracted b y th e lig h t while all o th er tr o u t appeared un affected .
E ig h ty -e ig h t cu tth roat, 5 brook and 17 bull tr o u t > 100 mm total
le n g th w ere o b se rv e d (Table 19).
Numbers of cu tth ro a t tr o u t counted
at n ig h t w ere alm ost double daytime w inter counts (Table 19).
In c re a ses w ere noticeable in all size c la ss e s (Table 19).
Winter
nighttim e co u n ts of 100-300 mm cu tth ro a t tro u t (N=53) more closely
approxim ated summer daytime co u n ts (N=46) than w in ter daytime
co u n ts (N=24 & 25).
As du rin g th e day, most tr o u t w ere o b serv ed in pools at n ig h t
du rin g w inter 1985-86 (Table 18).
Trout in riffle areas w ere of all
54
size c la sse s.
One cu tth roat tro u t (100-200 mm) was o b serv ed restin g
on th e su b stra te.
Winter 1986-87 - Day and Night
Winter d a y lig h t d iv e s w ere perform ed on January 9 (section II),
and F ebruary 22 (sectio n III).
January 9, 1987.
A w in ter n ig h t dive was perform ed on
Air and w ater tem p eratures recorded in 1986-87
w ere similar to 1985-86 (Air range=-15 to - 1 .1 0C; w ater range= -1 .1 to
2.2°C).
A verage air tem p eratures fo r th e en tire w inter (November -
February) w ere 1.8°C warmer in 1986-87 (p ersonal communications
National Weather S erv ice, Great Falls, MT).
The January 9, 1987 daytime sn o rk el count was perform ed in
section II from 1:30 to 3:40 pm.
-15.0 and 0°C, r e sp e c tiv e ly .
p resen t.
Air and w ater tem p eratu res were
V isibility was ex cellen t and sh e lf ice was
C utthroat tr o u t num bers w ere le s s variable in 1986-87 than
in 1985 du rin g w inter (Table 20).
N in e ty -se v en cu tth ro a t were
cou n ted du rin g 1986 w in ter d ays, compared to 125 d u rin g summer
days and 71 d u rin g fall days (Table 20).
Numbers o f tr o u t < 300 mm
(N=74) w ere interm ediate betw een summer (N=IOl) and fa ll (N=49) 1986
num bers.
A nighttim e sn o rk el cou n t was also perform ed in Section II.
Air
and w ater tem perature w ere -13.3 and -1.1°C , r e sp e c tiv e ly , and the
moon w as 3 /4 fu ll.
The nighttim e co u n t (N=84) was similar to the
daytime cou n t (N=97) (Table 19).
in 1985-86.
Diel variation was not as e v id e n t as
Still, few er tro u t w ere see n in w inter th an in summer.
55
Table 20.
Number of th ree sp e cie s of tro u t o b serv ed in section II of
R attlesnake Creek, January 9, 1987 during day (W) and
n ig h t (N) compared to summer (S), fall (F) and w inter (W)
1985-86.
Cutthroat
Size
(mm)
1985
si Wz
100-200
24
17
16
200-300
22
7
300-400
22
400+
Total
1
2
3
4
5
6
=
=
=
=
=
=
7 /1 0 /8 5
12/11/85
2 /1 0 /8 6
7 /1 2 /8 6
11 /1 /8 6
1 /9 /8 7
„3
T
Brook
Bull
F5
W/N6
T
W6
73
26
32/44
4
I
9
28
23
42/20
8
3
25
17
19
16
15/18
0
2
9
9
4
5
6
8/2
0
5
77
58
46
125
71
97/84
12
11
56
Section III, w hich froze over com pletely in 1985-86, was partially
open on F ebruary 22, 1987.
Trout in each of th e fiv e pools snorkeled
w ere p h y sica lly confin ed due to h ea v y icing in riffle sectio n s.
se v e n cu tth roat tr o u t w ere counted (Table 21).
F ifty -
This com pares to
en tire sectio n cou n ts of 54 and 129 in summer and 38 and 96 in fall.
In Section III, num bers of tro u t per pool w ere similar to section II
w hich gen erally rem ained ice free.
A lthough d iffe re n c e s in season al and diel abundance w ere le ss
e v id e n t in 1986-87 th an in 1985-86, behavior was similar betw een
years.
Trout a g g r eg a ted in high c la ss pools and ru n s (up to
34/pool).
A g g r essiv e behavior was not o b serv ed .
u sed sh e lf ice for cover.
C utthroat trout
In one in sta n ce, 15 cu tth ro a t tr o u t < 300
mm w ere o b se rv e d crow ded under an area of sh elf ice.
The ice was
in ten tion ally broken and th at n ig h t no cu tth roat tr o u t w ere ob serv ed
in th e area.
The section was not sn ork eled the next day.
Debris
cover and subm erged leaf p iles w ere u se d fr e q u e n tly w hen ice was
not available.
Five tr o u t w ere seen r estin g on the bottom and sev era l
trou t (at le a st 8) faced downstream.
Behavior o b serv ed in 1987 which
was not c o n siste n t w ith oth er y ea rs inclu ded no tro u t o b serv ed in th e
su b str a te , none fe e d in g , and tro u t bein g le s s active and alert bn
January 9th.
57
Table 21.
Summer (su) 1985 and 1986, fall 1985 and 1986, and
w inter (w) 1986-87 daytime cu tth roat trou t cou n ts
in Section III of R attlesnake Creek.
Cfi
C
CO
Size
Fall4
100-200
11
0
75
38
27
30
200-300
26
13
37
31
25
20
300-400
13
21
13
21
12
6
400+
4
4
4
6
3
I
Total
54
38
129
96
67
57
Su1
1
2
3
4
5
6
=
=
=
=
=
=
6 /2 0 /8 5
10/18/85
7 /1 3 /8 6
10/29/86
10/31/86
2 /2 2 /8 7
Fall23
N ight5 W 6
58
DISCUSSION
Population C harstcteristics
S p ecies Composition
Based on sn o rk el cou n ts, sp e c ie s com position in R attlesnake
Creek w as 83% cu tth roat, 10% bull and 7% brook trou t.
Brook trout
w ere th e on ly exotic tr o u t sp e cie s found in R attlesnake Creek.
w ere not p r e se n t in or above sectio n IV.
They
W hitefish, alth ough
probab ly n ative to th e lower rea ch es o f R attlesnake Creek, w ere also
not p r e se n t in th e stu d y sectio n s.
Local r e s id e n ts b eliev e sp e c ie s rela tiv e abundance may. have
ch anged du rin g th e p a s t 50 yea rs.
A ccording to th ree long-tim e
r e sid e n ts from th e R attlesnake Creek area, cu tth ro a t tr o u t w ere th e
dominant sp e c ie s in th e ea rly 1920’s.
fish in g p r e ssu r e in crea sed .
fis h at regu lar in ter v a ls.
In th e 1930’s, a c c e s s and
One fisherm an adm itted to tak in g 100+
Heavy fish in g p r e ssu r e con tin u ed from th e
m id-1920’s u n til it was prohib ited in 1937.
By th e late 1930’s, brook
tr o u t com position had in creased to approxim ately 35-40% o f th e catch
(p ersonal communication, F orest Poe, Ed Ray, and Ray N elson).
After
R attlesnake Creek was clo sed to fis h in g , cu tth roat tr o u t d en sities
in crea sed and brook tro u t d e n sitie s d ecreased .
C utthroat tro u t are
again th e dominant sp e c ie s and brook tr o u t have been p r e se n t for th e
59
la st 50+ years.
This s u g g e s ts th a t in th e ab sen ce of fish in g p ressu re
and th e p resen ce o f adequate habitat, cu tth roat tro u t may be able to
outcom pete brook trout.
Competition betw een n ative and introd uced salm onids is often
liste d as a reason for th e decline of n ative sp ecies; how ever,
experim ental t e s t s o f in ter sp e cific com petition betw een n a tiv es and
exotics have not been rigorou s (F ausch 1988).
There are few detailed
accou n ts and d escrip tio n s of in sta n ce s w here brook tr o u t have
outcom peted cu tth roat tr o u t (L iknes 1984).
Griffith (1988) s u g g e s ts
th at brook tro u t rep lace cu tth ro a t w here th e la tter have been
elim inated.
In th e laboratory and in a small stream in north ern
Idaho, e q u a l-siz e d brook tro u t did not e ffe c tiv e ly d isplace cutthroat
tr o u t (G riffith 1972).
In th e same s tu d y , brook tr o u t in itiated 40%
few er a g g r e s s iv e en co u n ters th an cu tth ro a t trout.
In a lake settin g ,
Magnan (1988) show ed th a t th e p r e se n c e o f oth er fis h sp e c ie s had a
n eg a tiv e impact on brook tr o u t pop ulations.
The g rea ter com parative size of cu tth ro a t tr o u t in R attlesnake
Creek may p artially explain w hy th e y are c u rren tly dominant over
brook tro u t.
Size w as th e primary fa cto r in determ ining th e w inner
o f a n ta g o n istic en co u n ters betw een wild cu tth roat and h atch ery
rainbow (P etro sk y and Bjornn 1988) and betw een brook tro u t and
brown tro u t (F ausch and White 1981).
In R attlesnake Creek, average
cu tth ro a t tro u t le n g th is 61 mm g rea ter th an brook trou t.
Greater fitn e s s and adap tive behavior of native cu tth ro a t tro u t
may also con trib u te to th eir dominance in R attlesnake Creek.
Early
60
stu d ie s of n ative v e r s u s introd uced tr o u t sto ck s show ed th a t native
tro u t had a com petitive advan tage o v er introduced sp e c ie s due to
g reater fitn e s s and adap tive behavior (Needham and S later 1944; Miller
1954, 1958; Reimers 1957; in P etro sk y and Bjornn 1988).
R attlesnake
Creek appeared to p rovid e optimal cu tth ro a t tro u t h ab itat w hich may
in crease th eir com petitive advan tage.
S h ifts in sp e c ie s com position betw een cu tth roat and brook tro u t
are o ften a ttrib u ted to th e p resen ce or a b sen ce o f an glin g.
D ifferen ces in an glin g vu ln era b ility of brook and cu tth ro a t tro u t has
been show n b y MacPhee (1966) and G riffith (1972).
MacPhee (1966)
found th at cu tth ro a t tr o u t w ere tw ice a s e a sy to ca tch a s brook
trout.
Moyle and Vondracek (1985) sta te th at once cu tth ro a t trou t
are rep laced b y another salmonid sp e c ie s, th ey are u n lik ely to regain
th at space.
In c a se s of contin uin g hab itat degradation, in tro g ressio n ,
and o v er-ex p lo ita tio n th is may hold tru e.
However, th er e is some
ob servation al ev id en ce in R attlesnake Creek th a t cu tth ro a t trout
d eclin es may have b een rev e r se d .
W estslope cu tth ro a t tr o u t in R attlesnake Creek w ere hybridized
w ith rainbow and Y ellow stone cu tth ro a t trout.
Genetic r e su lts from
th e 1985 High Falls Creek specim en w ere 96% w estslo p e cutthroat, 4%
rainbow and 2% Y ellow stone cu tth ro a t tro u t, while th e 1986 Pilcher
Creek sample had a g en etic m ake-up o f 80% w estslo p e cu tth roat and
20% rainbow trout.
Yellow stone cu tth ro a t tro u t have b een stocked in
some o f th e h ig h mountain la k es in th e up per drainage and rainbow
tro u t w ere probably planted or th e y may have m igrated upstream
61
from th e Clark Fork River (before th e dam was built).
Cutthroat
trou t size in th e low er sectio n s may be influenced by th eir genetic
m ake-up.
Trout Size and A bundance
Trout size varied betw een fish e d and u n fish ed sec tio n s (F igures
12 and 13, Appendix B), bu t d iffe re n c e s w ere more lik ely related to
habitat rath er than an glin g p r e ssu r e .
For example, tr o u t were
sm allest in section IV (Table 4) w hich is h igh er in th e drainage
(Figure I) w here w ater tem peratures are lower.
If th e small size of
tro u t in section IV was due to fish in g p r e ssu r e , e v en sm aller trout
would have b een exp ected in sectio n III w here an gler p r e ssu r e was
greater (F igure 6).
This was not th e case.
In addition, section II
(u n fish ed ) and sectio n III (fish ed ) had sim ilar-sized cu tth ro a t trout.
A bundance of tr o u t also va ried betw een fish e d and u n fished
sectio n s.
However, th e se d ifferen ces cannot be a ttrib u ted to fish in g.
Section IV (fish ed ) contained la rg er num bers of cu tth ro a t trout
(1985=374, 1986=385) th an th e u n fish ed section II (1985=153, 1986=276)
(Tables 27, 29, 31, and 33, Appendix A).
One year o f catch and release fish in g , after a 45 year closure,
did not red u ce abundance or av era g e size of cu tth ro a t trout.
The
d ecrease in av era g e le n g th from 257 mm in 1985 to 226 mm in 1986
was probably due to in creased em phasis on marking smaller trout.
Population abundance flu ctu a ted sea so n a lly and ann ually bu t th ere
w ere no c o n siste n t tren d s.
A follow -up stu d y would provide more
62
inform ation on lon g-term e ffe c ts o f catch and relea se fish in g .
High num bers o f r esid e n t tro u t, esp ecia lly large tro u t, were
found th ro u g h o u t R attlesnake Creek.
A verage summer cu tth roat trou t
num bers w ere 5 20/ kilom eter w ith 11% o v er 300 mm.
A verage len gth
of bull tro u t (241 mm) was also la rg e for th is size o f stream.
R esident bull tr o u t up to 711 mm w ere captu red du rin g fall trapping.
Numbers of bull tr o u t p er kilom eter could not be calcu lated due to
small sample size.
A lthough p r e se n t, brook tro u t w ere small (average
length= 175 mm) and gen era lly occu pied sid e chann els and beaver
ponds.
^
Comparable cu tth ro a t and bull tro u t siz e s are not found in
similar, fish e d tr ib u ta r ies of Rock Creek or the B itterroot, Clark Fork,
and Flathead r iv e r s (P eters 1988, Thomas 1984, Shepard e t al. 1982).
For example, P eters' (1988) did not cap tu re cu tth roat tr o u t larger th an
305 mm in eith er Daly Creek or th e West Fork of Rock Creek in 1985,
1986, and 1987.
Sim ilarly, Thomas (1984) found th e maximum size of
cu tth roat tr o u t to be 305 mm in 15 trib u ta ries to th e Clark Fork
River.
On nine tr ib u ta r ies to th e B itterroot River, no bu ll trout
larger th an 315 mm w ere captu red (P eters 1987).
The St. Joe and
Coeur d ’Alene River d rainages in north ern Idaho also su p p o rt few er
num bers o f large cu tth ro a t ev en in stream s with r e s tr ic tiv e
regu lation s (Thurow and Bjornn 1978, L ew ynsky and Bjornn 1983).
Thurow and Bjornri (1978) found th a t on ly 1% of th e cu tth ro a t tro u t
w ere la rg er th an 250 mm in Big and Marble Creeks (open to fish in g )
w hile in Quartz and Simmons C reeks (tr o p h y -fish reg u la tio n s), an
63
avera g e of 7% o f th e cu tth ro a t tro u t w ere larger than 250 mm.
In
Yellowstone Park, on ly la rg er drainages contain comparable sizes and
num bers of cu tth roat tro u t (Carty e t al. 1986).
The large size of cu tth ro a t and bull tro u t can probably be
a ttrib u ted to th e lack o f fish in g p r e ssu r e .
In a stu d y of an
unexploited population of smallmouth b a ss (M icro p teru s dolomieui), th e
population had an u n u su ally h igh p ercen ta g e of la rg e fis h (Reed and
Rabeni 1989).
C hanges in tro u t size have been docum ented with
regu lation ch a n g es.
Large tro u t (>405 mm) in crea sed from 1.9% to
9.1% o f th e population a fter a slo t limit was implemented on th e South
Fork Snake River (Thurow e t al. 1988).
Similar in c r ea se s have been
docum ented in Y ellow stone Park (G ressw ell and Varley 1988) and the
St. Joe River in Idaho (Thurow and Bjornn 1978).
The R attlesnake
Creek stu d y and o th er s (MacPhee 1966, Parma and D eriso 1990) have
show n th at an glin g is size sele c tiv e .
Larger fish are o ften more
vu ln erab le to an glin g p r e ssu r e and th erefo re rem oved from the
population fir st.
Snorkel Method
Population abundance and sp e c ie s com position w ere determ ined
prim arily b y sn ork elin g.
A ccording to G riffith e t al. (1983), the
fe a sib ility o f u sin g sn ork elin g a s a data collection tech n iq u e depend s
on com patible data n eed s, good w ater cla rity , sa fe ty , and behavior of
fish (o b serv a b ility ).
Our data n eed s w ere com patible, w ater cla rity in
R attlesnake Creek was good, flow s w ere gen erally low en ou gh to
sn ork el sa fe ly , and o b serv a b ility w as good ex cep t fo r w ith brook and
64
bull trou t.
Since th e em phasis of th is stu d y was on cu tth ro a t trout,
o b se rv a b ility of brook and bull tr o u t was not a major factor.
Additional reason s for sele c tin g th e sn o rk el method in R attlesnake
Creek w ere th e low w ater co n d u ctiv ity and corresp on d in g in efficien cy
of e lec tr o fish in g .
The sn ork el method has proven s u c c e s s fu l over a
w ide ran ge of stream siz e s (N orthcote and Wilkie 1963, Schill and
G riffith 1984, Slaney and Martin 1987, Zubik and Fraley 1988, Hankin
and R eeves 1988), b u t Hankin and R eeves (1988) found sn ork el counts
w ere most accu rate in small stream s similar to R attlesnake Creek.
To in crea se accu racy of th e sn o rk el method, P eterso n markrecap tu re estim ates w ere calcu lated.
Trout w ere marked by angling
and "recaptured" by sn ork el ob servation .
Hook and lin e mark,
followed by sn o rk el-reca p tu re estim ates (or sn o rk el-P eterso n
estim ates) w ere determ ined to be th e b e s t of th ree underw ater
m ethods te s te d b y Zubik and Fraley (1988).
P ossib le so u r ce s of
erro rs w ere red u ced b y marking approxim ately 20% o f th e trout
population w hen p o ssib le (V incent 1971) and by u sin g fou r tag colors
(one for each size c la ss) to in crea se th e accu racy of size estim ation
(Slaney and Martin 1987).
may have b een violated .
An assum ption of the P eterso n method
Immigration or em igration may have occurred
betw een th e mark and recap tu re ru n s.
This assum ption is often
violated u sin g o th er m ethods.
D isadvantages o f th e sn ork el method include d iv er error and low
o b serv a b ility of small cu tth ro a t tr o u t and all brook and bull trou t
(Millis and Pardue 1984, Slaney and Martin 1987, Shepard and
65
Graham 1983).
Supplem ental e lec tr o fish in g ru n s w ere made to increase
th e accu racy of estim ates in th ese grou p s.
Diver erro r (double
cou n ts and failure to d e te c t trou t) was red uced by snorkeling only on
d ays w ith good lig h tin g and by moving slow ly upstream in order to
d ecrease chance of d istu rb in g trout.
A ngler U se and Catch
Even w ith th e rela tiv ely low fish in g p r e ssu r e in R attlesnake
Creek, cu tth ro a t tr o u t w ere ca u g h t in h ig h er p roportion s (92%) than ^
th eir rela tiv e abundance (79.5%).
W estslope cu tth ro a t tro u t are
op p ortu n istic fe e d e r s and th eir lack o f s e le c tiv ity makes them
extrem ely vu ln erab le to an glers.
C utthroat tro u t vu ln era b ility to a n g lin g has been well
docum ented (S ch ill e t al. 1986, MacPhee 1966).
MacPhee found th at
cu tth ro a t tr o u t w ere about tw ice a s e a sy to catch as brook trout.
Schill e t al. (1986) rep orted th a t cu tth ro a t in Y ellow stone Park were
cap tu red an avera g e of 9.7 tim es in 108 days.
T w en ty-on e p ercen t of
cu tth ro a t ta g g e d in R attlesnake Creek w ere recap tu red and one tro u t
was ca u g h t 12 tim es in 12 months.
be much le s s vu ln erab le.
Rainbow tro u t have b een shown to
Riehle e t al. (1989) rep orted th a t rainbow
tro u t in a catch and relea se area w ere on ly cau gh t th re e tim es during
each an glin g season .
The decline o f w estslo p e cu tth ro a t tro u t is
o ften a ttrib u ted to over-exp lo ita tio n (L ikn ess and Graham 1988,
G riffith 1988, G ressw ell and Varley 1988).
A ngling in R attlesnake Creek w as size sele c tiv e .
C utthroat ov er
66
400 mm had th e h ig h e st an gling reca p tu re rate (68%) while the 100200 mm cu tth roat recap tu re rate was on ly 8%.
Gard and S e e g rist
(1972) rep orted th at wild tro u t could su p p o rt a su b sta n tia l h a rv est
over time and remain viab le bu t th e rem aining population would not
have many large trout.
Other au th ors rep o rt a d ecrea se in size with
in crea sed exploitation (Barnhart 1989, McDonald and H ershey 1989,
Olson and Cunningham 1989).
A ccording to Parma and Deriso (1990),
s iz e -s e le c tiv e an glin g may alter p h en otyp ic com position among
su r v iv o rs.
Based on th e se fin d in g s, o th er w estern Montana stream s
may no lon ger be able to produce cu tth ro a t tro u t as la rg e as th o se in
R attlesnake Creek.
Good su r v iv a l among ca u g h t and relea sed cu tth ro a t tro u t in
R attlesnake Creek was ind icated by th e h igh p ercen t o f reca p tu res
and stab le num bers of large cu tth ro a t tro u t betw een 1985 and 1986.
Schill e t al. (1986) rep orted hooking m ortality for cu tth ro a t tro u t on
th e Y ellow stone River to be le s s th an 1%.
During th is s tu d y , c re e l c e n su s data ind icated th a t catch and
release regu lation s on R attlesnake Creek p ro tected la r g er , older
cu tth ro a t tr o u t and, w ithin th e sh o rt duration of th e stu d y , trout
d e n sitie s did not d ecrease.
In 1985 and 1986, an glin g p r e ssu r e was
low and catch ra tes w ere high.
In 1985, an estim ated 457 an glers
fish e d th e stream du rin g th e 25-w eek c e n su s period compared to 254
in 1986.
Catch ra tes in crea sed from 3.0 c u tth r o a t/h o u r in 1985 to 3.4
c u tth ro a t/h o u r in 1986, w hich in d ica tes th a t p r e ssu r e in 1986 did not
d ecrease due to a lack of an gler su c c e s s.
Catch r a tes w ere varied, in
67
oth er stu d ie s bu t an gling p r e ssu r e was gen erally h ig h er (Carty e t al.
1986, Thurow and Bjornn 1978, P eters 1983, and Shepard e t al. 1982).
Catch ra tes w ere 0.9 tr o u t/h o u r on th e Yellowstone River with 36,600
an gler days in 1985 (Carty e t al. 1986).
Catch ra tes w ere 1.3
cu tth ro a t/h o u r on Big Creek, a trib u ta ry to th e St. Joe River in
Idaho, w ith 1015 a n g lers (Thurow and Bjornn 1978).
On Rock Creek,
catch ra tes for cu tth roat, brown, brook, and rainbow tro u t w ere 1.2
tr o u t/h o u r (P eters 1983).
Of th e se stu d ie s, only th e Flathead river
system and trib u ta ries had h igh er ca tch ra tes (9.6 cu tth ro a t/h o u r)
(Shepard e t al. 1982).
Seasonal Movement P attern s
Based on trap p in g and an gler recap tu re, cu tth ro a t tro u t
movements w ere small and direction o f movement was variable.
Only
11% of 222 recap tu red fish moved o u t of th e section w here th ey w ere
ta g g ed .
Nine o f them moved upstream and 17 moved downstream.
Only se v e n of th e recap tu red tro u t moved more th an 1.6 km; six of
th e se w ere le s s th an 300 mm total len g th .
Brook and bull trout
movements could not be determ ined from tag retu rn data.
Traps w ere in stalled in R attlesnake Creek in 1986 a fter recording
a large number of cu tth roat tro u t 100 to 200 mm total le n g th (306
cap tu red ) moving th ro u g h sectio n I in A ugust, 1985.
A lthough th e
tra p s w ere s e t betw een July 21 and October 3, 1986, a similar
movement p attern was not recorded.
F o r ty -six cu tth ro a t, 28 brook,
and 30 bull tro u t w ere captu red in tra p s above and below section II.
68
Most cu tth roat and brook tro u t trapp ed w ere le s s th an 300 mm total
len gth .
E v erest (1971) su g g e ste d th a t fr y migration may be a function of
crow ding.
As fish grow th e amount of liv in g space d eclin es, and th is
crow ding may in itiate a downstream movement.
The la rg e numbers of
100-200 mm cu tth roat tr o u t I o b serv ed moving th ro u g h sectio n I may
su p p ort th e crow ding h y p o th esis.
Bachman (1984) found th at
h atch ery tro u t w ere o ften excluded from a c ce ss to te r rito rie s by
r esid e n t trou t, su g g e stin g th at subordin ate trou t may g en era lly tend .
to be displaced.
Most cu tth roat tr o u t w hich moved in R attlesnake
Creek w ere < 300 mm.
Jones e t al. (1978) noted th a t peak migration
in H atchery Creek occu rred during a hard rainstorm.
Flows increased
in R attlesnake Creek in A u g u st,. 1985 b u t not in 1986.
Riley et al.
1992 p ostu lated th e ex isten ce o f two com ponents of stream fish
populations: a large sta tic and a small mobile com ponent.
Static tro u t
esta b lish te r r ito r ie s and mobile tro u t presum ably move w hen th ey are
unable to compete for space.
Based on th e tag r etu r n s, trap p in g, and
ob serv a tio n s in R attlesnake Creek, th ere is evid en ce fo r both a sta tic .
and a mobile component.
Seasonal Habitat U tilization and Behavior
Summer
Habitat selectio n and behavior of cu tth ro a t tr o u t during d a y lig h t
hours in early summer (June 1-23) w ere associated w ith spaw ning.
Adult tr o u t sele c te d pools and ru n s w here g ra v els w ere available.
69
Trout exhibited a g g r e s s iv e behavior and fed freq u en tly .
Habitat selection and behavior d u rin g mid-summer (June 23 Septem ber 15) appeared related to feed in g .
As pool and run habitats
stagn ated , adu lt tro u t moved into r iffle areas.
Campbell and Neuner
(1985) found th at in summer rainbow tro u t w ere located adjacent to
fa s t moving w ater w here th e y could tak e advan tage of incoming d rift
organism s.
Trout in riffle, areas g en era lly w ere v isu a lly isolated from
each oth er and a g g r e s s iv e behavior w as in freq u en tly o b serv ed .
In
R attlesnake Creek cu tth roat < 300 mm gen erally inh abited riffle areas
th rou gh ou t th e summer.
Trout < 100 mm u su ally occu pied w aters near
th e stream m argins or in sid e ch an n els w here water v e lo citie s were
low.
In th e summer, Hillman e t al. (1987) ob serv ed 95% of a g e-0
chinook salmon in pool or glide habitat w here v e lo citie s w ere also low.
O bservations d u rin g one summer nighttim e d ive (Ju ly 28),
ind icate th at cu tth roat tro u t occu pied th e same habitat a t n igh t as
during the day.
Campbell and Neuner (1985) found th a t rainbow tro u t
moved in sh ore to r e s t during summer n ig h ts.
We did not o b serv e
th is movement, alth ough o th er fa cto rs (m oonlight e tc.) could have
a ffected th is behavior.
Fall
Trout a g g r eg a ted in high c la ss pools (4 or 5, Table 3) during
autumn d ays w hen w ater tem peratures dropped below 6.5 ° C.
Campbell and Neuner (1985) rep orted similar behavior in rainbow
trout.
Cunjak and Power (1986) also o b serv ed brook tro u t
70
a g g r eg a tin g in fall.
Other b eh aviors (a g g r e ss iv e n e ss , feed in g ,
placem ent in w ater column, etc.) w ere interm ediary betw een summer
and w inter in R attlesnake Creek.
Numbers of cu tth ro a t tro u t < 300 mm d ecreased in fall 1985 in
sec tio n s I, II, and III, bu t no similar decrease was o b se rv e d in 1986.
Higher mean w ater tem p eratures in 1986 may partially accou nt for th is
d ifferen ce.
E v er e st e t al. (1985) rep o rted num bers o f steelh ea d tro u t
d ecreased du rin g fall.
A lthough B jornn (1971) concluded th at low
tem p eratures in d u ced fish to seek sh e lte r in th e su b str a te , in 1986,
w hen w ater tem p eratu res dropped to 0°C, cu tth roat tr o u t num bers in R attlesnake Creek did not d ecrease.
This s u g g e s ts th a t w ater
tem perature was not th e only fa cto r in flu en cin g tr o u t behavior.
Other fa cto rs may have inclu ded lack of ice formation and sh orter
duration o f su b zero periods.
Fall n igh t-tim e sn ork el cou n ts w ere not condu cted in 1985.
1986 day and n ig h t co u n ts w ere similar.
In
This co n tr a sts w ith fin d in g s
of Campbell and N euner (1985) who rep o rted th a t a d u lts, ju ven ile, and
fr y em erged from th e su b str a te du rin g fall n ig h ts (8-3° C).
Hillman e t
al. (1987) found th a t some of th eir marked ju v en ile chinook salmon
moved to areas along u n d ercu t ban ks w here d en se grow th s of se d g e s
and g r a s s e s o ffered cover.
S u b stra te and oth er co v er was available
in R attlesnake Creek in th e fall b u t was not u sed u n til w inter.
During th is stu d y w ater tem p eratures du rin g fall 1986 may have been
too mild to ind uce th is behavior.
71
Winter
O bservations made in 1985-86 du rin g fiv e w inter sn o rk el cou n ts
ind icated th a t habitat u se and behavior changed betw een summer and
w inter.
In w inter, tro u t a g g reg a ted in pools similar to fall and made
le s s u se o f r iffle areas.
Chapman and Bjornn (1969) s u g g e ste d th at
th ere w ere e n e r g y sa v in g a d v a n ta g es fo r tro u t th a t occu p ied deeper,
q u ieter w ater a sso cia ted w ith co v er in th e w inter.
A lthough pools
and r u n s w ere p r eferred in R attlesnake Creek, some tr o u t (N=52) w ere
o b serv ed in r iffle hab itat during w inter.
Hillman e t al. (1987) did not
o b se rv e an y ju v en ile chinook salmon in riffle habitat.
Trout o b se rv e d in R attlesnake Creek gen erally fa ced upstream ,
b u t it w as not uncommon to see them "milling" in o th er directions.
S everal w ere c lo se ly a ssociated w ith th e bottom and a few w ere seen
r estin g d ir e ctly on th e su b stra te.
Rainbow tro u t have b een ob serv ed
r e stin g on th e stream bed during w inter n ig h ts (Campbell and Neuner
1985).
H ierarchical siz e -r e la te d social s tr u c tu r e s and a g g r e s s iv e
in tera ctio n s w ere not o b se rv e d in R attlesnake Creek.
Small tro u t
(< 200 mm) w ere o b se rv e d swimming a d ja cen t to la rg e tr o u t (>350 mm)
w ithout an y reaction from th e la rg er fish .
A g g r essiv e in teraction s
may r e p r e se n t an u n p rofitab le e n e r g y ex p en d itu res in w inter.
Most
tro u t w ere le s s approachable by th e sn ork eler in w in ter th an in
summer.
B ustard and N arver (.1975) fou nd a pronounced fr ig h t
reaction o f coho salmon and steelh ea d tr o u t to a sn o rk eler in w inter.
Other r ese a rc h e rs have found th a t low w ater tem p eratures red uce fish
swimming perform ance (Hartman 1963 and B rett e t al. 1958).
Swimming
72
perform ance of cu tth roat tro u t in R attlesnake Creek did not appear to
be a ffected during sh o rt fleein g b u r sts.
Winter co v er in R attlesnake Creek co n sisted o f sh e lf ice, debris,
subm erged leaf p iles, u n d ercu t ban ks, and occasionally aquatic
v eg eta tio n .
Hillman e t al. (1987) fou nd th a t 90% of ju v en ile salmon
and steelh ead tro u t u se d subm erged sed g e and g r a ss e s overh an gin g
u n d ercu t banks.
This ty p e of hab itat was not available in R attlesnake
Creek in w inter alth ou gh u n d ercu t ban ks w ere u sed .
Campbell and
N euner (1985) o b se rv e d fr y u sin g subm erged leaf p iles fo r cover in
w inter.
*
Trout up to 150 mm total le n g th u sed lea f p iles fo r cover in
R attlesnake Creek.
Trout o b se rv e d du rin g my stu d y appeared to
p refer overh ead ice co v er, bu t I did not collect quantifiable data to
v e r ify th is ob servation .
The MDFWP (1984) sp ecu la ted th a t sh elf ice
may p rovid e co v er from p red a to rs, in su la te a g a in st radiant heat lo ss,
and p r e v en t su p er cooling of th e stream .
Maciolek and Needham
(1952) found th a t stream salm onids ap p aren tly did not seek su b stra te
sh e lte r in w inter w hen ice co v er was available.
Areas w ith anchor ice
w ere avoided.
Only one tro u t was o b serv ed fe e d in g in R attlesnake Creek during
a w inter day.
D ifferen t feed in g behavior in w inter has been noted in
o th er stu d ies.
Maciolek and Needham (1952) o b serv ed tro u t a ctiv ely
feed in g du rin g w inter (0°C).
B ustard and Narver (1985a) ob serv ed
tro u t fe e d in g w hen w ater tem p eratures w ere above 7°C, b u t steelh ead
tro u t and coho salmon varied betw een b ein g a ctiv e and in a ctiv e at
tem p eratures betw een 4 and 7°C.
No ju v en ile steelh ea d w ere
73
o b serv ed feed in g at low w ater tem peratures in the Sarita River
(B ustard and N arver (1985b).
Winter daytime cu tth roat tro u t co u n ts w ere alw ays le s s than
summer daytime cou n ts.
Winter num bers of cu tth roat tro u t < 300 mm
w ere le s s th an half th e num bers o b se rv e d in summer.
The presen ce
of small cu tth roat tro u t at n ig h t b u t not during th e day may indicate
th at th e se tr o u t hid in th e su b str a te , u n d er aquatic v eg eta tio n , or in
d eb ris dams.
Similar behavior has b een rep orted by E v erest e t al.
(1985) and Chapman and Bjornn (1968).
In con clu sion , th e size and abundance of tro u t in R attlesnake
Creek was sig n ifica n tly larger th an sim ilar-sized stream s.
One year
of catch and relea se an glin g had no m easurable a ffe c t on the trout
population, how ever, a follow -up stu d y would provide inform ation on
th e long-term e ffe c ts o f an glin g.
A 68% recapture rate o f cutthroat
tro u t < 400 mm in d ica tes th e h igh v u ln era b ility to a n g lin g esp ecia lly
compared to smaller size c la sse s and o th er sp ecies.
Abundance of
cu tth roat varied con sid erab ly betw een sea so n s and diel s h ifts were
noted in th e w inter.
Seasonal and diel s h ifts in hab itat u se have w idespread
im plications in management.
High qu ality pools, co v er, and adequate
flow s are im portant hab itat criteria fo r w inter su rv iv a l.
In Montana,
stream carryin g cap acity may be s e t by th e amount of w inter habitat
available.
74
LITERATURE CITED
75
LITERATURE CITED
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Lolo
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v
76
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77
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78
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79
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83
APPENDICES
APPENDIX A
TABLES
85
Table 22.
R attlesnake Creek w ater a n a ly sis, 10/28/85 and
12/16/86. Data from Mountain Water Company, Missoula.
C onstituent
1985
(m g/L)
Potassium
Sodium
Calcium
Magnesium
Sulfate
Chloride
Carbonate
Bicarbonate
Nitrate as N
Iron
Total Solids (Calculated)
Total H ardness as CaCoS
pH, standard u n its
Floride
A rsenic
Barium
Cadmium
Chromium
Lead
M ercury
Selenium
S ilver
<1
<1
3
I
3
I
0
26
<0.05
<0.03
22
13
6.9
<0.10
<0.005
<0.1
<0.002
<0.02
<0.01
<0.001
0.005
<0.005
(I
2
5
2
4
I
0
18
<0.05
<0.03
23
19
6.6
<0.10
<0.005
<0.1
<0.001
<0.02
<0.01
<0.001
0.005
<0.005
Sp ecific Conductance @ 25°C
36 mhos/cm
44mhos/cm
1986
(mg/L)
86
Table 23.
L ocation o f s tu d y s e c tio n s and landm arks in th e
R a ttlesn a k e C reek d ra in a g e.
Area
Road Kilometers
Spring Creek
F raser Creek
Bottom of section
Top of sectio n I
Old sig n hole
Bottom of section
Top of section II
B eescove Creek
Bottom of section
Top of section III
Franklin Bridge
Bottom of sectio n
Top of section IV
Table 24.
I
II
III
IV
0
5.0
6.6
7.2
8.2
8.5
9.2
9.5
9.7
10.3
12.4
15.3
15.8
Legal D escription
T14N, R18W, sec 20 ac
T14N, R18W, sec 21 aa
T14N, R22W, sec 15 cd
T14N, R22W, sec 2 bd
Sample c re e l c e n su s form u sed in the v o lu n teer creel
box, 1985 and 1986.
Comments:
Date fish ed :______ Stay o v e rn ig h t ____ y e s _____ no
Area
B eesk o v eFished: Franklin Br. _____
# < 8"
Rainbow tro u t
C utthroat trou t
Hybrid (RB x CT)
Brook trou t
Bull trou t
Franklin Br.
Porcupine Cr._____
# 8-12"
# 12-16"
Hours fish ed
Above
Porcupine C r._
# > 16"
87
Table 25.
Allele freq u en cies at th e loci th at d ifferen tia te
w estslop e cu tth roa t and rainbow trou t in sam ples
collected from R attlesnake Creek in 1985 and 1986.
The allele ch a ra cteristics of w estslope cu tth ro a t trout
at each locu s is listed fir st.
Alleles
1985
1986
d.f.
200
250
100
0.922
0.063
0.800
0.017
0.183
I
4.161*
84
100
0.922
0.078
0.800
0.200
I
3.943*
92
100
0.953
0.047
0.767
0.233
I
9.183**
86
100
114
71
40
20
0.469
0.242
0.008
0.016
0.266
0.375
0.383
0.017
0.208
0.017
3
6.257
88
100
0.969
0.031
0.767
0.233
I
11.409***
40
100
0.922
0.078
0.767
0.233
I
5.734*
A verage w estslop e
0.938
0.778
A verage rainbow
0.062
0.222
Locus
Aatl
Ck2
Gpi3
Idh3,4
Mel
Sdh
-
-
x2
Notes: d.f. = d e g r ee s of freedom , x = co n tin g en cy tab le ch i-sq u a re
te s t for hom ogeneity of allele fr e q u e n c ie s, * = P<0.05, ** = P<0.01,
*** = PCO.OOl. The freq u en cy of th e Idh3, 4 86 allele is usually 0.500
in pure populations of w estslo p e cu tth ro a t trout. The proportion of
w estslop e in th e sam ples at th ese loci, th erefo re, is estim ated to be
tw ice th e fre q u e n c y of th is allele. The 1985 sample con tain s some
Yellowstone cu tth roat tro u t gen etic material. Thus, th e proportion of
w estslop e cu tth ro a t tro u t gen etic material in th is sample is lik ely to
be underestim ated and th e proportion of rainbow tro u t gen etic
material to be overestim ated.
88
Table 26.
Date
T rou t p o p u la tio n e stim a tes fo r se c tio n I (0.6 km) of
R a ttlesn a k e C reek, 1985.
S p ecies
Size
M1
C2
R3
N4
95%CI
Spring
Day
4 /9 /8 5
CT*
All
4
6
2
10.7
7.9
Summer
Day
8 /4 /8 5
CT
All
71
348
41
597.0
176.4
100-200
200-300
300-400
400+
37
18
12
4
306
19
19
4
22
6
11
2
506.0
53.3
20.7
7.3
194.7
29.8
7.1
4.5
Bull
All
27
25
3
182.0
146.7
Brook
All
31
20
4
134.4
93.9
Fall
Day
10/29/85
CT
All
12
23
6
43.6
25.4
I
I
9
I
3
9
8
3
0
I
4
I
7.0
9.0
17.0
2.4
8.4
9.1
8.9
1.6
Winter
Day
12/10/85
CT
All
28
8
100-200
200-300
300-400
400+
5
7
13
2
0
2
6
I
100-200
200-300
300-400
400+
* c u tth r o a t tr o u t
l=m arked; 2= cap tu red ; 3= recap tu red ; 4=num ber estim a ted
89
Table 27.
T rou t p o p u la tio n e stim a te s fo r se c tio n II (0.6 km) of
R a ttlesn a k e C reek, 1985.
Date
Sp ecies
Size
M1
C2
Spring
Day
4 /9 /8 5
CT*
All
10
Summer
Day
7 /1 0 /8 5
CT
All
100-200
200-300
300-400
400+
Fall
Day
10/17/85
R3
N4
23
6
36.7
21.4
59
79
30
153.8
37.7
16
20
18
5
24
22
22
9
5
8
12
5
69.8
52.7
32.6
9.0
44.6
25.5
13.3
4.2
95%CI
Brook
All
9
16
2
55.7
49.5
CT
All
26
31
11
71.0
35.5
100-200
200-300
300-400
400+
0
9
10
7
0
5
19
7
0
0
7
4
All
59
19
100-200
200-300
300-400
400+
17
7
25
10
0
4
10
5
CT
Winter
Day 12/11/85
* c u tth r o a t tr o u t
l=m arked; 2= cap tu red ; 3= recap tu red ; 4=num ber estim a ted
_
59.0
26.5
11.8
74.7
13.4
5.8
90
Table 28.
T rou t p o p u la tio n estim a tes fo r se c tio n III (0.6 km) of
R a ttlesn a k e C reek, 1985.
Date
Sp ecies
Size
M1
C2
R3
Summer
Day
6 /2 0 /8 5
CT*
All
54
54
100-200
200-300
300-400
400+
6
19
25
4
Fall
Day
10/18/85
CT
All
100-200
200-300
300-400
400+
N4
95%CI
19
150.3
51.3
11
26
13
4
3
6
8
2
20.0
76.1
39.4
7.3
14.3
45.4
14.6
4.6
25
38
15
62.4
22.8
0
11
12
2
0
13
21
4
0
3
10
2
_
41.0
25.0
4.0
30.4
10.0
2.5
♦cutthroat trou t
l=marked; 2=captured; 3=recaptured; 4l=number estim ated
Table 29.
Trout population estim ates for section IV (0.6 km) of
R attlesnake Creek, 1985.
Date
Sp ecies
Size
M1
CT*
All
150
Summer
Day
8 /2 5 /8 5
Fall COUNT
Day
10/29/85
100-200
200-300
300-400
400+
C2
95XCI
R3
N4
168
67
374.3
68.3
52
93
5
0
80
80
8
0
16
45
5
0
251.5
161.0
8.0
103.3
29.5
3.5
2
23
2
23.0
21.1
Bull
All
CT
All
234
39
100-200
200-300
300-400
400+
74
147
13
0
4
31
I
0
* cu tth roat trou t
l=marked; 2=captured; 3=recaptured; 4=number estim ated
91
Table 30.
T rou t p o p u la tio n e stim a tes fo r se c tio n I (0.6 km) of
R a ttlesn a k e C reek, 1986.
Date
S p ecies
CT*
All
100-200
200-300
300-400
400+
Brook
Fall
Day
10/29/86
M1
C2
R3
N4
106
57
35
10
4
98
55
29
11
3
46
20
20
4
2
221.1
153.7
50.4
25.4
5.7
All
19
25
5
85.7
Bull
All
0
CT
All
100-200
200-300
300-400
400+
brook
Summer
Day
7 /2 8 /8 6
Summer
Night
7 /2 8 /8 6
Size
11
—
95%CI
45.3
50.8
11.5
15.5
2.8
—
106
57
35
10
4
94
45
31
13
5
36
14
15
5
2
273.7
176.9
71.0
24.7
9.0
All
19
4
I
49.0
bull
All
0
8
-
CT
All
100-200
200-300
300-400
400+
52
24
11
14
3
84
36
35
10
3
20
8
3
8
I
212.0
101.8
107.0
17.3
7.0
76.9
54.8
88.4
4.6
5.6
brook
All
30
23
2
247.0
226.4
bull
All
5
5
I
17.0
15.7
* c u tth r o a t tr o u t
l=m arked; 2= cap tured ; 3= recap tu red ; 4=num ber estim a ted
-
68.0
71.2
23.9
13.8
6.8
-
92
Table 31.
T rou t p o p u la tio n e stim a tes fo r se c tio n II (0.6 km) of
R a ttlesn a k e C reek, 1986.
Date
S p ecies
Size
M1
C2
CT*
All
100-200
200-300
300-400
400+
104
41
32
26
5
125
73
28
19
5
brook
All
13
bull
All
CT
N4
95%CI
46
12
15
16
3
275.6
238.1
57.0
30.8
8.0
62.4
114.0
18.1
5.5
4.1
5
0
69.0
95.6
4
6
2
10.7
7.9
All
100-200
200-300
300-400
400+
92
55
18
19
2
71
26
23
16
6
24
4
8
10
2
266.8
290.2
49.7
31.0
6.0
82.9
209.6
24.4
10.4
4.4
brook
All
14
-
-
bull
All
33
11
I
203.0
209.7
CT
All
100-200
200-300
300-400
400+
92
55
18
19
2
92
62
14
15
I
27
10
7
9
I
307.9
319.7
34.6
31.0
2.0
93.7
164.3
15.4
11.2
-
brook
All
14
3
0
19.0
9.3
Bull
All
33
12
I
220.0
229.0
Winter
Day
1 /9 /8 7
CT
Night
1/9 /8 7
CT
All
100-200
200-300
300-400
400+
All
100-200
200-300
300-400
400+
Summer
Day
7 /1 2 /8 6
Fall
Day
11/1 /8 6
Fall
Night
1 1/3/86
R3
97
32
42
15
8
84
44
20
18
2
♦cu tth roat trou t
l=marked; 2=captured; 3=recaptured; 4=number estim ated
93
Table 32.
T rou t p o p u la tio n e stim a te s fo r se c tio n III (0.6 km) of
R a ttlesn a k e C reek, 1986.
Date
S p ecies
CT*
All
100-200
200-300
300-400
400+
brook
Fall
N ight
10/31/86
Winter
2 /2 2 /8 7
M1
C2
R3
N4
95XCI
108
42
46
16
4
129
75
37
13
4
37
12
17
6
2
369.0
250.4
98.2
33.0
7.3
97.4
119.4
32.0
16.2
4.5
All
10
8
2
32.0
25.6
bull
All
2
9
I
14.0
14.2
CT
All
100-200
200-300
300-400
400+
96
50
28
15
3
96
38
31
21
6
34
11
7
13
3
276.8
164.8
115.0
24.1
6.0
69.9
74.5
65.1
7.4
3.5
brook
All
29
12
3
96.5
70.4
bull
All
17
8
3
39.5
25.8
CT
All
100-200
200-300
300-400
400+
96
50
28
15
3
67
27
25
12
3
22
8
4
7
3
285.8
177.5
149.8
25.0
3.0
93.0
90.6
107.7
10.1
brook
All
29
6
3
51.5
29.7
bull
All
17
11
I
CT
All
100-200
200-300
300-400
400+
Summer
Day
7 /1 3 /8 6
Fall
Day
10/29/86
Size
57
30
20
6
I
♦cu tth roat tro u t
l=marked; 2=captured; 3=recaptured; 4=number estim ated
-
—
-
94
Table 33.
T rou t p o p u la tio n e stim a te s fo r se c tio n IV (0.6 km) of
R a ttlesn a k e C reek, 1986.
Date
S p ecies
Size
M1
CT*
All
100-200
200-300
300-400
400+
174
82
82
10
-
195
89
93
13
-
bull
All
13
54
Summer
Day
C2
R3
N4
95XCI
88
35
47
6
-
385.4
206.5
159.2
20.4
58.8
51.5
31.4
10.0
-
6
109.0
70.6
* cu tth roat trou t
l=marked; 2=captured; 3=recaptured; 4=number estim ated
APPENDIX B
FIGURES
Relative Frequency (%)
96
Section III
(64)
100 126 160 176 200 226 260 276 300 326 360 376 400 425
100 126 150 175 200 226 250 276 300 326 360 376 400 425
Total Length (mm)
Figure 12.
Length frequency distribution of cutthroat trout
captured in sections I-IV of Rattlesnake Creek, summer
1985.
Sample sizes are shown in parentheses.
97
Section I
(106)
Relative Frequency (%)
125 160 175 200 226 260 276 300 325 360 375 400 426
25
Section Il
(104)
20
16
10
6
0
100 126 160 176 200 226 260 276 300 326 360 376 400 425
Section IV
(174)
100 126 160 175 200 225 260 276 300 326 360 375 400 426
Total Length (mm)
Figure 13.
Length frequency distribution of cutthroat trout
captured in sections I-IV of Rattlesnake Creek, summer
1986. Sample sizes are shown in parentheses.
98
5
Section I
(57)
■■
■
mm
■
■
■
< 0)0
■
■■■■
■ ■ ■
■
■ mm
mmI
J _ _ _ _ _ I_ _ _ _ _ |_ _ _ _ _ I
l
l
l
I
i
l
l
l
_____ I
75 100 125 160 175 200 225 260 276 300 325 360 375 400 426 450 475
L en g th (mm)
S ection Il
(54)
■
■ ■ ■
■S ■ ■ ■ ■ ■ ■
*
a mm
a a mm
am m
a
m
<
C0)0
I
I_ _ _ _ _ I_ _ _ _ _ I
I
I
I
I
I
I
I
i
75 100 125 150 176 200 225 250 275 300 325 360 376 400 425 450 475
L en g th (mm)
Figure 14.
Age and length, determined from scales, of cutthroat
trout in sections I and II of Rattlesnake Creek, 1985.
Sample sizes are shown in parentheses.
99
5
Section III
- (48)
4
■■
3
< OD CD
2
mm
S
-
Ij L
i_ _ _ _ _
I_ _ _ _ _ _ I
i
i
i
_ _ _ _ _ I_ _ _ _ _ i
i_ _ _ _ _ I_ _ _ _ _ I
i
i
i
i
_____ I
75 100 125 150 175 200 226 260 276 300 325 360 376 400 426 460 476
L en g th (mm)
Section IV
(143)
< CD®
76 100 125 150 175 200 225 250 275 300 325 350 376 400 425 450 475
L en g th (mm)
Figure 15.
Age and length, determined from scales, of cutthroat
trout in sections III and IV of Rattlesnake Creek, 1986.
Sample sizes are shown in parentheses.