REFP:%B;4 "fl a w - 14

Do Not Remove from the L i b r ~ r J

U. S. Fish and Wildlife Service -

National Wetlands Research Center Biological Report 82(11.86) 700 Cajun Oome Boulevara January 1989 Lafayette, Louisiana 70506 TR EL-82-4

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and l nvertebrates (Pacific Northwest)

SEA-RUN CUTTHROAT TROUT

Fish and Wildlife Service Coastal Ecology Group

Waterways Experiment Station

U.S. Department of the Interior U.S. Army Corps of Engineen

B i o l o g i c a l Report 82(11.86) TR EL-82-4 January 1989

Species Pro f i 1 es: L i f e H i s t o r i e s and Environmental Requi rements o f Coastal Fishes and Inver tebra tes ( P a c i f i c Northwest)

SEA-RUN CUTTHROAT TROUT

G i l b e r t B. Pauley, Kevin Oshima, Karen L. Bowers, and G. L . Thomas Washington Cooperative Fishery Research U n i t

School o f F i she r ies U n i v e r s i t y o f Washington

Sea t t l e , WA 98195

P r o j e c t O f f i c e r David Moran

U.S. F ish and W i l d l i f e Serv ice Nat iona l Wetl ands Research Center

1010 Gause Boulevard S l i d e l l , LA 70458

Th is study was conducted i n cooperat ion w i t h

Coastal Ecology Group Waterways Experiment S t a t i o n U. S. Army Corps o f Engineers

Vicksburg, MS 39180

Performed f o r

U.S. Department o f t h e I n t e r i o r F i sh and W i l d l i f e Serv ice Research and Development

Nat ional Wetl ands Research Center Washington, DC 20240

This ser ies may be referenced as f o l l o w s

U.S. F i sh and W i l d l i f e Service. 1983-19 . Species p r o f i l e s : l i f e h i s t o r i e s and environmental requirements o f c o a s t 5 f i s h e s and inver tebra tes . U. S. F i sh Wi ld l . Serv. B i o l . Rep. 82(11). U.S. Army Corps o f Engineers TR EL-82-4.

Th is p r o f i l e may be c i t e d as fo l lows:

Pauley, G.B. , K. Oshima, K. L. Bowers, and G. L. Thomas. 1989. Species p r o f i l e s : 1 i f e h i s t o r i e s and environmental requirements o f coas ta l f i s h e s and i nve r teb ra tes ( P a c i f i c Northwest)--sea-run c u t t h r o a t t r o u t . U.S. F i sh Wild. Serv. B i o l . Rep. 82(11.86). U. S. Army Corps o f Engineers TR EL-82-4. 2 1 pp.

PREFACE

This species p r o f i l e i s one o f a se r i es on coasta l aquat ic organisms, p r i n c i p a l l y f i s h , o f spor t , commercial, o r eco log ica l importance. The p r o f i l e s are designed t o prov ide coasta l managers, engineers, and b i o l o g i s t s w i t h a b r i e f comprehensive sketch o f t h e b i o l o g i c a l c h a r a c t e r i s t i c s and environmental requirements o f t h e species and t o descr ibe how populat ions o f t h e species may be expected t o r e a c t t o environmental changes caused by coasta l development. Each p r o f i l e has sect ions on taxonomy, 1 i f e h i s to ry , eco log ica l r o l e , environmental requirements, and economic importance, i f appl i cab le . A th ree - r i ng b inder i s used f o r t h i s se r i es so t h a t new p r o f i l e s can be added as they are prepared. Th is p r o j e c t i s j o i n t l y planned and f inanced by t h e U.S. Army Corps o f Engineers and the U.S. F i sh and W i l d l i f e Service.

Suggestions o r questions regard ing t h i s r e p o r t should be d i r e c t e d t o one of t he f o l l owing addresses.

I n fo rma t ion Trans fer S p e c i a l i s t Nat ional Wetlands Research Center U.S. F i sh and W i l d l i f e Serv ice NASA-Sl i d e l l Computer Complex 1010 Gause Boulevard S l i d e l l , LA 70458

U.S. Army Engineer Waterways Experiment S t a t i o n A t ten t i on : WESER-C Post O f f i c e Box 631 Vicksburg, MS 39180

CONVERSION T A B L E

M e t r i c t o U.S. Customary

Mu1 t i p l y

m i l l i m e t e r s (mm) cen t ime te rs (cm) meters (m) meters (m) k i l o m e t e r s (km) k i 1 ometers (km)

square meters (m2) 10.76 square k i l o m e t e r s (km2) 0.3861 hectares (ha) 2.471

l i t e r s (1) cub ic meters (m3) cub ic meters (m3)

m i l l i g r a m s (mg) grams (g) k i 1 ograms (kg) m e t r i c tons (t) m e t r i c tons (t)

k i l o c a l o r i e s ( k c a l ) C e l s i u s degrees ( O C )

U. S. Customary t o M e t r i c

inches 25.40 inches 2.54 f e e t ( f t ) 0.3048 fathoms 1.829 s t a t u t e m i l e s ( m i ) 1.609 n a u t i c a l m i l e s (nmi) 1.852

square f e e t ( f t2 ) square m i l e s ( m i 2 ) acres

g a l l o n s ( g a l ) cub ic f e e t ( f t3) a c r e - f e e t

ounces (oz) ounces (oz) pounds ( l b ) pounds ( l b ) s h o r t tons ( t o n )

B r i t i s h thermal u n i t s (Btu) Fahrenhe i t degrees (OF)

To Obta in

inches inches f e e t fathoms s t a t u t e m i l e s n a u t i c a l m i l e s

square f e e t square m i l e s acres

g a l 1 ons cub ic f e e t a c r e - f e e t

ounces ounces pounds pounds s h o r t tons

B r i t i s h thermal u n i t s Fahrenhe i t degrees

m i l l i m e t e r s cen t ime te rs meters meters k i l o m e t e r s k i l o m e t e r s

square meters square k i l o m e t e r s hec ta res

1 i t e r s cub ic meters cub ic meters

m i l l i g r a m s grams k i 1 ograms m e t r i c tons m e t r i c tons

k i l o c a l o r i e s C e l s i u s degrees

CONTENTS

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i ii CONVERSION TABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i v ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v i

NOMENCLATURE/TAXONOMY/RANGE . . . . . . . . . . . . . . . . . . . . . . . . 1 MORPHOLOGY/IDENTIFICATION AIDS . . . . . . . . . . . . . . . . . . . . . . . 1 REASON FOR INCLUSION I N SERIES . . . . . . . . . . . . . . . . . . . . . . . 4 LIFE HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spawning 4 Eggs and Fecund i ty . . . . . . . . . . . . . . . . . . . . . . . . . . 6 A l e v i n s a n d F r y . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Juven i l es and Srnol ti ng . . . . . . . . . . . . . . . . . . . . . . . . 6 Sa l twa te r L i f e . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

AGE AND GROWTH CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . 7 ECOLOGICALROLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 ENVIRONMENTALREQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . 9

Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Subs t ra te and Cover . . . . . . . . . . . . . . . . . . . . . . . . . . 10 D isso lvedOxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 T u r b i d i t y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Water V e l o c i t y . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Water Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2

. . . . . . . . . . . . . . . . . . . . . . . . . . . . T i rnberHarves t 1 2 THE FISHERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5

ACKNOWLEDGMENTS

The authors thank James Johnston o f the Washington Department o f Game and Howard Fuss o f the Washington Department o f Fisheries f o r t h e i r reviews and technical suggestions.

F igu re 1. Sea-run c u t t h r o a t t r o u t .

SEA-RUN CUTTHROAT TROUT

S c i e n t i f i c name.. . .Salmo c l a r k i c l a r k i --- Prefe r red common name. ... Sea-run c u t -

t h r o a t t r o u t (F igure 1) .. Other common names. .Coastal cu t -

t h r o a t t r o u t , r ed - th roa ted t r o u t , sea t r o u t , sea-run c u t t h r o a t , sea- r un cu t , b l ueback t r o u t , autumn t r o u t , ha rves t t r o u t , y e l l o w b e l l y .

Class ..................... Oste ichthyes Order .................... Salmoniformes Fami ly ...................... Salmonidae

Geographic range: I n coas ta l streams from no r the rn C a l i f o r n i a th rough Oregon and B r i t i s h Columbia and i n t o southeastern Alaska (F igures 2 and 3). Rare ly found more than 160 km i n l and .

MORPHOLOGY/IDENTIFICATION AIDS

The f o l l o w i n g i n f o r m a t i o n i s taken f rom H a r t (1973), S c o t t and Crossman (1973), and Wydoski and Whitney (1978). Morphologica l d i f f e r e n c e s

between coas ta l c u t t h r o a t and i n l a n d c u t t h r o a t were o u t l i n e d b y Qad r i (1959) and T r o t t e r (1987).

Morphology: F i n rays--dorsal f i n 8-11, anal 8-12, p e c t o r a l s 13, and p e l v i c 9. Adipose, smal l , f l e s h y and s lender , p e l v i c s abdominal i n p o s i t i o n w i t h a f r e e - t i p p e d f 1 eshy appendage above i n s e r t i o n . Cyc lo i d scales, 120- 180 a t l a t e r a l 1 ine ; g i l l r ake rs 15- 22, rough and w ide l y spaced on f i r s t g i l l arch. Body e longate, s l i g h t l y compressed.

I d e n t i f i c a t i o n a ids : Red o r orange s t reak a long t h e i n n e r edge o f lower jaw i n f r e s h specimens. Small t e e t h a t t h e back o f t h e tongue between t h e second g i l l c l e f t s . Teeth w e l l developed on upper and lower jaws. M a x i l l a r y u s u a l l y extends beyond t h e p o s t e r i o r margin o f t h e eye i n f i s h longer t han 10 cm. Back i s greenish- b l u e t end ing toward metal 1 i c b l u e i n f resh sea-run f i s h ; s ides s i l v e r y ; d i s t i n c t b l a c k spots on back, head,

Figure 2. Map showing major r i v e r s t h a t support sea-run c u t t h r o a t t r o u t i n the P a c i f i c Northwest. It should be noted t h a t many small streams too numerous t o be shown on t h i s map a l s o support sea-run cu t th roa ts . An a c t i v e spo r t f i s h e r y

MILES 0 0 0 50 100

. r1.

KILOMETERS

exists for these fish in saltwater throughout Puget Sound and Hood Canal as well as in the rivers.

Figure 3. Sea-run c u t t h r o a t t r o u t coasta l d i s t r i b u t i o n from nor thern C a l i f o r n i a t o southeastern Alaska and the general l i m i t s o f i n l a n d d i s t r i b u t i o n i n North America ( a f t e r Johnston and Mercer 1976).

anal f i n , t a i l , and s ides (extending spo r t f i s h e r y takes p lace i n the f a l l , w e l l below l a t e r a l l i n e ) . Size range wh i l e an extensive sa l twater spo r t o f adu l t s i s 0.5 t o 2.7 kg. f i s h e r y e x i s t s year round i n i n l a n d

waters such as Puget Sound. The sea- run c u t t h r o a t i s h i g h l y sought a f t e r

REASON FOR INCLUSION IN SERIES by f l y - f i shermen.

Although no t q u i t e as well-known as i t s l a r g e r cousin the steelhead (Salmo LIFE HISTORY a r d r ) , the sea-run c u t t h r o a t t r o u t i s ex tens i ve l y sought by anglers Spawn i ng through the r i v e r s and small streams o f Northern Cal i f o r n i a , Oregon, Sea-run c u t t h r o a t t r o u t have a v a r i - Washington, and B r i t i s h Columbia t h a t ab le l i f e h i s t o r y , which w i l l be d i s - f l o w i n t o sa l twater . The f reshwater cussed below. L i ke salmon, sexual l y

mature sea-run c u t t h r o a t t r o u t r e t u r n t o t h e i r na ta l streams t o spawn. Spawning sea-run c u t t h r o a t t r o u t home p r e c i s e l y t o s p e c i f i c t r i b u t a r i e s , wh i l e immature f i s h do not always r e t u r n t o t h e i r home stream t o feed o r when seeking an overwin ter h a b i t a t (Johnston 1982). Homing o f na t i ve sea-run c u t t h r o a t i s extremely prec ise (Campton 1980), a1 though hatchery- p lan ted f i s h may s t r a y as much as 30%, which makes su rv i va l ra tes impossib le t o determine (Johnston and Mercer 1976). Gel e lec t ropho re t i c s tud ies have shown t h a t c u t t h r o a t populat ions are genet ica l l y d i s c r e t e a t t he small stream l e v e l (Campton 1980), a1 though the re i s 1 i m i t e d h y b r i d i z a t i o n w i t h hatchery-propagated s t e e l head t r o u t (Campton and U t t e r 1985).

The t ime o f r e t u r n t o freshwater f o r spawning i s f a i r l y cons i s ten t among c u t t h r o a t t r o u t from the same stream, b u t va r i es w ide ly by geographical l o c a t i o n (Johnston and Mercer 1976; Johnston 1982). I n Oregon and Washington, c u t t h r o a t t r o u t re -enter f reshwater anytime from J u l y through March (Sumner 1952; Anderson and Narver 1975). Very few overwin ter i n sa l twater (Johnston 1982). A spr ing run has been observed on l y i n Alaska (Jones 1972). I n add i t i on , a small percentage o f t he immigrants are sex- ua l l y immature i n d i v i d u a l s (Jones 1973-76; Johnston 1982; T ipp ing 1986). I n most coas ta l r i v e r s o f Washington and Oregon, t he stocks o f f i s h are sexua l ly mature a t f i r s t r e t u r n t o freshwater; however, a 1 arge percent- age o f c u t t h r o a t females i n t h e Columbia River , Puget Sound, B r i t i s h Columbia, and Alaska do no t spawn dur ing the w i n t e r o f t h e i r f i r s t r e t u r n t o f reshwater (Johnston 1982). Anadromous c u t t h r o a t t r o u t t r a v e l f a r t h e r upstream toward the headwaters o f t h e watershed than e i t h e r steelhead t r o u t o r coho salmon and rea r sympat- r i c a l l y w i t h r e s i d e n t c u t t h r o a t popu- l a t i o n s (Johnston 1982; Michael 1983).

Spawning genera l ly takes p lace i n l a t e w i n t e r and spr ing, b u t t i m i n g

va r i es by geographic 1 o c a t i on (Dymond 1932; Cramer 1940; Sco t t and Crossman 1973). I n Puget Sound and southern B r i t i s h Columbia, coas ta l c u t t h r o a t t r o u t e x h i b i t two d i s t i n c t m ig ra t i on times: (1) f i s h r e t u r n i n g t o l a rge r i v e r systems begin en te r i ng i n J u l y and peak i n September-October ( e a r l y e n t r y f i s h ) and (2) f i s h r e t u r n i n g t o small streams d r a i n i n g d i r e c t l y t o sa l twa te r begin en te r i ng i n November and peak i n January-February (1 a te e n t r y f i s h ) (Johnson 1982; Mercer 1982). Th is d i f f e r e n c e i s most l i k e l y due t o food avai 1 ab i 1 i t y , sa l twa te r to1 erance, o r stream f lows (Johnston 1982). Throughout t h e i r range, sea- run c u t t h r o a t t r o u t spawn i n small t r i b u t a r i e s o f l a rge o r small streams w i t h a drainage area l ess than 13 km and may thereby avo id compet i t ion f o r r e a r i nq area w i t h stee'l head (sea-run rainbow t r o u t , Sal mo g a i rdner; ) and coho salmon (0-h nchus k i su tch ) (Cramer 1940; A Sumner 19 2; DeWitt 1954; Glova and Mason 1977; ~ o h n s t o n 1982). Cut th roat t r o u t p r e f e r spawning h a b i t a t w i t h smal l - t o - moderate-size gravel (Hunter 1973).

Spawning behavior i n c u t t h r o a t t r o u t i s t y p i c a l o f o the r stream-spawning salmonids such as steelhead and salmon (Smith 1941; Cope 1957; Scot t and Crossman 1973). The female d igs a redd i n t he gravel and deposi ts her eggs. Simultaneously, t he male covers t h e eggs w i t h m i l t . The female then bu r ies the eggs under a l a y e r o f g rave l . A1 though c u t t h r o a t t r o u t a re repeat spawners, post-spawni ng mor- t a l i t i e s are sometimes h igh due t o weight l oss and t h e r i g o r s o f spawning (Cramer 1940; Sumner 1952; Giger 1972; Sco t t and Crossman 1973). The f i s h t h a t su rv i ve migra te downstream i n e a r l y t o l a t e spr ing. Ke l t s (spent adu l t s ) en te r sa l twa te r e a r l i e r than smol t i n g j u v e n i l e s (Giger 1972; Jones 1975). Sumner (1952) s ta ted t h a t 39% o f t h e c u t t h r o a t surv ived the f i r s t spawning i n Oregon, 17% the second, and 12% t h e t h i r d . These data are representa t ive o f cond i t i ons where a ta rge ted c u t t h r o a t f i s h e r y does not

e x i s t . S p o r t f i s h i n g pressure reduces t h e s u r v i v a l o f s ~ a w n i n a adu l t s f o l l o w i n g t h e f i r s t m' igrat i& (Giger 1972).

Eggs and Fecundity

The spher ica l eggs o f c u t t h r o a t t r o u t range i n s i z e from 4.3 t o 5 .1 mm i n d i ameter. Fecundity depends on t h e s i z e and age o f t h e female. I n Alaska, f i s h rang ing i n s i z e from 34 t o 46 cm produced 486 t o 2,286 eggs pe r female (Jones 1975). I n Washington, females rang ing from 20 t o 43 cm produced 226 t o 4,420 eggs (Johnston and Mercer 1976). Average number o f eggs was between 1,100 and 1,700 f o r females o f a l l s izes pooled (Scot t and Crossman 1973). Mercer (1982) showed a s t rong l i n e a r cor- r e l a t i o n between increased l eng th and 1 ncreased number o f eggs, w i t h an "r" value o f .97. Eggs normal ly hatch i n 28 t o 40 days, b u t may r e q u i r e 50 days o r more (Merriman 1935; Cope 1957; Sco t t and Crossman 1973). Hatching i s temperature-dependent (Merriman 1935).

A lev ins and Fry

Newly hatched yo1 k-sac 1 arvae, c a l l e d a lev ins , remain i n t he gravel i n t h e redd f o r 1 t o 2 weeks before they emerge as fry. The f ry are l ess than 3 cm long and commonly 1 i v e i n t he shal low, l ow-ve loc i t y stream margi ns (Johnston and Mercer 1976). However, t h e i r d i s t r i b u t i o n i s o f t e n governed by t h e presence o f o the r sa l - monid species (see Eco log ica l Role sect ion) . The f i r s t scales are formed when t h e f i s h are 3.5 cm i n f o r k l eng th (FL)--a l eng th normal ly a t t a i n e d du r ing the f i r s t summer o f l i f e (Cooper 1970; Giger 1972).

The f ry are s e n s i t i v e t o many k inds o f environmental changes. Logging (Mori ng and Lantz 1974), increased temperatures (Go1 den 1975), 1 oss o f cover (Lowery 1965), reduct ions i n food supply, and s i 1 t a t i o n (Bustard and Narver 1975) can a l l increase

l a r v a l morta l i ty. Johnston and Mercer (1976) l i s t e d a number o f na tu ra l sources o f m o r t a l i t y , such as i n t e r - s p e c i f i c compet i t ion w i t h o the r salmonids, i n t r a s p e c i f i c compet i t ion, and crowding induced by low summer f lows, b u t they i nd i ca ted t h a t h a b i t a t a l t e r a t i o n was probably t he g rea tes t t h r e a t t o c u t t h r o a t t r o u t stocks.

Juveni 1 es and Smol ti ng

P r i o r t o smol t ing and e n t e r i n g s a l t - water, juven i 1 es (par r ) may migra te up- and downstream several t imes (Sumner 1953; Moring and Lantz 1975). Th is m ig ra t i on can r e s u l t i n confusion f o r someone t r y i n g t o count o r e s t i - mate t h e number o f smol t i n g c u t t h r o a t t r o u t m ig ra t i ng downstream and ou t i n t o the marine environment. The age a t which smol t ing f i r s t occurs i s extremely va r i ab le , be ing somewhat size-dependent and occu r r i ng between Age I and Age I V (Moring and Lantz 1975) o r even l a t e r (Johnston and Mercer 1976; Jones 1977; Fuss 1978). A good working average i s between Ages I11 and I V . Fuss (1978, 1982) noted t h a t most i n i t i a l migrants are Aged I11 o r I V and o u t l i n e d several rea- sons why i n i t i a l m ig ra t i on occurs a t d i f f e r e n t ages. F i sh i n these age groups average 20-25 cm FL. I n Wash- i ng ton and Oregon, downstream movement o f smolts takes p lace from March t o June, b u t peaks i n mid-May (Johnston and Mercer 1976).

A d i v i s i o n o f m ig ra t i on types seems t o e x i s t between c u t t h r o a t t r o u t en te r i ng the p ro tec ted water o f areas such as Puget Sound and those en te r i ng areas o f surf-pounded coast. Cut- t h r o a t t r o u t en te r i ng p ro tec ted waters are, on average, younger and smal le r (Age 11, 16 cm FL) (Michael 1983; Johnston 1980), whi 1 e those en te r i ng s u r f zones are, on average, Age I V and 2 1 cm (Fuss 1982). Regardless o f age o r h a b i t a t , c u t t h r o a t t r o u t school be fore e n t e r i n g t h e marine environment and remain schooled throughout t h e i r sa l twa te r migra t ions (Giger 1972)--a

behavior which probably has s u r v i v a l value.

Sal twater L i f e

Although the re have been few s tud ies o f c u t t h r o a t t r o u t movements a t sea, i t appears t h a t they overwinter i n t he marine environment and s tay c lose t o shore. A1 though c u t t h r o a t remain a t sea vary ing lengths o f t ime, they re- t u r n t o f reshwater i n t he same year i n which they migrated ou t t o sea (Giger 1972; Anderson and Narver 1975; Jones 1976; Johnston and Mercer 1976).

I n Puget Sound, Washington, t he anadromous c u t t h r o a t t r o u t feed and migrate along t h e beaches, most ly i n water l ess than 3-m deep (Johnston 1980). I n general, t h e i r movement along the coast i s be l ieved t o be cor- r e l a t e d w i t h onshore ocean cur ren ts , w i t h the f i s h s tay ing c lose t o t h e coast1 i ne (Giger 1972; Johnston and Mercer 1976). Regardless o f age, anad- romous c u t t h r o a t t r o u t a re be l i eved t o begin school ing j u s t be fore they enter i n t o the marine h a b i t a t (Johnston 1980). I n Alaska, c u t t h r o a t t r o u t were r e l u c t a n t t o cross bodies o f water 3 t o 8 km wide, and p r e f e r r e d t o f o l l o w t h e shore1 i n e (Jones 1976).

Many c u t t h r o a t t r o u t have been captured w i t h scars from predator a t t a c k w h i l e a t sea, and t h a t p redat ion i s be l ieved t o represent a major source o f marine m o r t a l i t y (Giger 1972). Estimates from Oregon s tud ies i n d i c a t e 20%-40% s u r v i v a l o f i n i t i a l migrant f i s h i n the marine environment (Giger 1972). T ipp ing (1986) noted t h a t s u r v i v a l was considerably h igher f o r hatchery sea- r u n c u t t h r o a t t r o u t t h a t were re leased as smolts >21 cm FL (12.8% re tu rns ) than f o r f i s h less than t h a t l eng th (2.3% re turns) .

AGE AND GROWTH CHARACTERISTICS

Growth i n c u t t h r o a t t r o u t va r i es according t o t he type o f f reshwater

and sa l twa te r environments they i nhab i t . Johnston and Mercer (1976) summarized growth o f a d u l t c u t t h r o a t t r o u t i n t h e P a c i f i c Northwest (Oregon, B r i t i s h Columbia, and Alaska) and s ta ted t h a t f i s h t h a t l i v e i n t he lower stream grow more r a p i d l y than f i s h t h a t res ide upstream and t h a t bas i c stream p r o d u c t i v i t y a l so in f luences growth. Nickelson and Larson (1974) i nd i ca ted t h a t coas ta l c u t t h r o a t t r o u t no t on l y l o s t weight when food i n streams was scarce, b u t t h a t they a l so decreased i n length. It i s no t known how f requen t l y t h i s occurs.

Giger (1972) c i t e d problems t h a t were inherent i n determining c u t t h r o a t t r o u t age and growth due t o v a r i a b l e 1 i f e cyc les and d i f f e r e n t m ig ra t i on s t ra teg ies . An unusual p a t t e r n o f age-length d i s t r i b u t i o n s e x i s t s f o r i n i t i a l outmigrants because t h e f i s h which spend more t ime i n streams p r i o r t o ou tmigra t ion grow slower. This slower growth may be a r e s u l t o f t h e greater compet i t ion f o r food i n streams than occurs i n t h e marine environment. The r e s u l t i s t h a t f i s h from t h e same system en te r i ng sa l twater f o r t he f i r s t t ime a t Age I V a re on l y s l i g h t l y l a r g e r than i n i t i a l outmigrants o f Age 11, and are much smal ler than Age I V f i s h t h a t have spent one o r more summers a t sea. Fuss (1978) i nd i ca ted t h a t back- ca l cu la ted lengths f o r young f i s h ( l ess than 2 years o ld ) may be i n e r r o r , bu t t he c a l c u l a t i o n s f o r f i s h 2 years o l d o r o lde r a re probably accurate because o f the near l i n e a r r e l a t i o n s h i p between f i s h l eng th and scale rad ius f o r t h e o lde r f i s h . According t o Fuss (1978), Age I + c u t t h r o a t ranged from 69 t o 121 mm and Age 11+ c u t t h r o a t from 140 t o 180 mm. These f i g u r e s may be mis leading because o f t h e a d d i t i o n a l (+) growth. I n a subsequent paper, Fuss (1982) i nd i ca ted more accura te ly t h a t Age I f i s h were 70-77 mm and Age I 1 f i s h were 100-113 mm. The l a t e r work invo lved more data and b e t t e r techniques. The growth r a t e i n more

nor thern streams i s slower than i n t he more southern streams (Johnston and Mercer 1976).

Cut th roat t r o u t can l i v e a maximum o f 10 years (Jones 1976), b u t most a d u l t f i s h runs are made up o f i n d i v i d u a l s between 3 and 6 years o f age (Johnston and Mercer 1976; Fuss 1982). Repeat spawners r e t u r n i n g f o r a f o u r t h o r f i f t h spawning a t t a i n lengths o f 17 t o 19 inches (Giger 1972; Johnston and Mercer 1976).

ECOLOGICAL ROLE

The use o f i s o l a t e d headwater streams by c u t t h r o a t t r o u t f o r spawning and the f i r s t years o f r e a r i n g serves t o reduce h y b r i d i z a t i o n i n t e r a c t i o n s w i t h o ther salmonids, p r i m a r i l y steelhead t r o u t and coho salmon, which t y p i c a l l y spawn and r e a r f u r t h e r downstream from nurs ing zones o f young-of-the-year and Age I c u t t h r o a t t r o u t (Johnston 1982). Hyb r id i za t i on between c u t t h r o a t t r o u t and hatchery rainbow t r o u t does no t occur i n t he few areas o f over lap (Sumner 1972; Campton 1980; Campton and U t t e r 1985). Sympatric and a1 l o - p a t r i c populat ions o f res iden t and anadromous c u t t h r o a t t r o u t may a1 so l i v e w i t h i n a watershed (DeWitt 1954; Royal 1972; Sco t t and Crossman 1973; Moring and Lantz 1975; Jones 1979; Johnston 1982). Another s e l e c t i v e advantage f o r i s o l a t i o n o f coasta l c u t t h r o a t t r o u t , according t o Johnston (1982), i s i n t he outcome o f soc ia l i n t e r a c t i o n s w i t h anadromous steelhead t r o u t and coho salmon. Competi t ive i n t e r a c t i o n s f o r food and space be- tween anadromous c u t t h r o a t t r o u t and steelhead t r o u t o r coho salmon juven i l es are most f requen t l y decided i n f avo r o f t h e steelhead t r o u t o r t he coho salmon (Glova and Mason 1976, 1977; Johnston 1982; Glova 1984). Coastal c u t t h r o a t t r o u t i n B r i t i s h Columbia a l so have evolved both a s p a t i a l and feeding segregation where they cohab i t w i t h t he predacious D o l l y Varden (Sa lve l inus malma) (Andrusak

and Northcote 1971; Schul tz and Northcote 1972).

Hab i ta t s e l e c t i o n by j u v e n i l e cu t - t h r o a t t r o u t appears t o be governed by the presence o f o ther salmonid species. I n t he absence o f competing species, c u t t h r o a t t r o u t have been found t o p r e f e r poo ls (Glova and Mason 1976; Johnston and Mercer 1976; Glova 1984). When sympatr ic w i t h coho salmon, soc ia l dominance i s asserted by the coho salmon due t o t h e i r e a r l i e r emergence and l a r g e r body s i z e (Glova and Mason 1976; Johnston 1982).

Cut th roat and rainbow t r o u t c o e x i s t i n t he same reaches o f many streams (Moring and Youker 1979; Nicholas 1978), and occasional l y they hyb r id i ze (Campton and U t t e r 1985). The upper reaches o f t he stream are usua l l y dominated by c u t t h r o a t t r o u t , whi 1 e rainbow t r o u t dominate t h e lower sec t ions (Hartman and G i l l 1968; Nicholas 1978). I n areas where anadromous rainbow t r o u t (steelhead) e x i s t , t h i s arrangement does no t always occur because the steelhead j uven i l es emigrate a t Age I and Age I 1 i n t h e spr ing , which leaves a v a i l a b l e the poo ls t h a t t h e o l d e r c u t t h r o a t t r o u t seem t o p r e f e r i n a l l sect ions o f t he streams (Johnston and Mercer 1976). It has been po in ted ou t t h a t t he re are th ree d i s t i n c t 1 i f e h i s t o r y types o f coasta l c u t t h r o a t t r o u t : on l y one o f these i s anadromous, wh i l e t he o ther two types spend t h e i r e n t i r e l i v e s i n f reshwater (Thomasson 1978; Michael 1983; Fuss 1982, 1984).

The r e s u l t o f i n t e r a c t i o n w i t h e i t h e r coho salmon o r rainbow t r o u t tends t o be the displacement o f t he juven i 1 e young-of- the-year c u t t h r o a t t r o u t from the p r e f e r r e d poo ls t o t he r i f f l e s . The c u t t h r o a t t r o u t gene ra l l y r e t u r n t o t he pools a f t e r fa1 1 i ng water temperatures reduce aggressive i n t e r a c t i o n w i t h these o ther species and t h e heavier w in te r f lows th reaten displacement from the r i f f l e s (Bustard and Narver 1975; Glova and Mason 1976).

Cut th roa t t r o u t a re o p p o r t u n i s t i c feeders (Behnke and Zarn 1976; Wydoski and Whi t ney 1978). Aquat ic i n s e c t s , g e n e r a l l y t he most a v a i l a b l e food i n streams, a re t he dominant i t em i n most c u t t h r o a t t r o u t d i e t s (Dimick and Mote 1934; Lowery 1966; A l l e n 1969; Carlander 1969; Baxter and Simon 1970; Sco t t and Crossman 1973; Hunter 1973; G r i f f i t h 1975; Glova 1984). Other foods, such as zooplankton (McAfee 1966; Carlander 1969; T ro jna r and Behnke 1974 ; Hi c kman 1977), t e r r e s t r i a l i nsec t s (Lowry 1966; Glova 1984; M a r t i n 1984), and f i s h (Car l ander 1969; Hunter 1973; M a r t i n 1984) a re impor tan t l o c a l l y o r seasonal ly . Many o f t h e coas ta l c u t t h r o a t s tocks t ime t h e i r runs t o co inc ide w i t h t h e a v a i l a b i l i t y o f salmon eggs i n t h e streams (Johnston 1982).

Cu t t h roa t t r o u t become more p i sc i vo rous as they increase i n s i z e ( I d y l l 1942; McAfee 1966; Carlander 1969; Baxter and Simon 1970; Wydoski and Whitney 1978). I n f reshwater , c u t t h r o a t t r o u t p rey on th reesp ine s t i c k l e b a c k (~astero; teus acul eatus) , sockeye salmon (Oncorhynchus nerka) , and coho salmon (Lowery 1966; Armstrong 1971). There is- consider- ab le s i m i l a r i t y and over lap i n t h e d i e t of young c u t t h r o a t t r o u t and young coho salmon, b u t d i r e c t c o n f l i c t may be avoided by h a b i t a t p a r t i t i o n i n g ( G l ova 1984). W i 1 zbach (1985) i n d i - cated t h a t food a v a i l a b i l i t y i s r a t h e r impor tan t i n de te rmin ing abundance and m i c r o h a b i t a t d i s t r i b u t i o n o f a d u l t c u t t h r o a t t r o u t w i t h i n a stream.

Freshwater p redators o f c u t t h r o a t f r y i nc l ude rainbow t r o u t , brook t r o u t ( ~ i - l v e l i n u s f o n t i n a l i s ) , Do1 l y Varden, and shorthead scu lp i ns (Cot tus confusus), as we1 1 as a d u l t c u t t h r o a t t r o u t (Horner and B io rnn 1976). Other poss ib l e predators- a re g r e a t b l u e herons ( ~ r d e a herodias) , be1 t e d k i ng f i shers (Cery l e a1 cyon) , and m i n k (Mustela v ison) accord ing t o Horner and B jornn(1976).

I n t h e marine environment, c u t t h r o a t t r o u t feed on gammarid amphipods, sphaeromid isopods, c a l l i a n a s s i d shrimp, immature crabs, and var ious f i s h , i n c l ud i ng chum salmon (Oncorhynchus keta) , p i n k salmon (Oncorhynchus gorbuscha), and P a c i f i c sand lance (Ammodytes hexapterus) (Armstronq 1971; Simenstad and Kinney 1978) ; h e r r i n g and scul p i ns a re a1 so eaten.

Predators o f sea-run c u t t h r o a t t r o u t i n t he marine environment i nc l ude P a c i f i c hake (Merl ucc i us productus) , sp iny dog f i sh (Squal us acanth ias) , harbor seal (Phoca v i t a l i n a ) , and a d u l t salmon ( ~ i T 1 9 7 7

ENVIRONMENTAL REQUIREMENTS

Temperature

Unusual stream temperatures can lead t o disease outbreaks i n m i g r a t i n g f i s h , a l t e r e d t i m i n g o f m ig ra t i on , and acce le ra ted o r re ta rded matura t ion (Reiser and B jo rnn 1979). Most s tocks o f anadromous salmonids have evolved t o t ake advantage o f temperature pa t t e rns i n t h e i r home streams, and s i g n i f i c a n t abrup t dev ia t i ons from t h e normal p a t t e r n can adverse ly a f f e c t t h e i r s u r v i v a l .

Cu t t h roa t t r o u t a re n o t usual 1 y found i n waters where t h e maximum temperature c o n s i s t e n t l y exceeds 22 O C , a l though they t o l e r a t e b r i e f per iods o f dayt ime water temperatures as h igh as 26 O C i f cons iderab le c o o l i n g takes p lace a t n i g h t (Behnke and Zarn 1976). B e l l (1973) repo r ted p r e f e r r e d temperatures o f 9 t o 12 O C

f o r c u t t h r o a t t r o u t , w i t h spawning temperatures f o r c u t t h r o a t t r o u t t h a t range from 6 t o 17 O C (Hunter 1973).

The d u r a t i o n o f egg i ncuba t i on v a r i e s and i s dependent upon tempera- t u r e (Merriman 1935); t h e optimum temperature f o r i ncuba t i on i s approx- ima te l y 10 t o 11 O C (Merriman 1935; Snyder and Tanner 1960). Egg s u r v i v a l

POPULATION * CONSUMPTION

TOTALSTOCK BIOMASS

0 WATER TEMPERATURE

FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DATE

Figure 4. Sea-run c u t t h r o a t t r o u t popu la t ion consumption and t o t a l s tock biomass (wet weight) versus temperature i n a 500-m long sec t i on o f Bear Creek, Washington (modi f i ed from M a r t i n 1984).

i s a l s o dependent upon temperature (Smith e t a1 . 1983).

Metabol i c r a t e s o f j u v e n i l e cu t - t h r o a t t r o u t a re h ighest between 11 and 2 1 O C (Dwyer and Kramer 1975). According t o M a r t i n (1984), s tock biomass remained nea r l y constant i n a g iven sec t i on of a small stream i n t h e P a c i f i c Northwest from J u l y t o September, b u t t he water temperature rose and food consumption increased para1 l e l t o t h i s r i s e (Figure 4). The opt imal temperature f o r j u v e n i l e s i s 15 O C , and e q u i l i b r i u m and ab i 1 i t y t o swim i s l o s t between 28 and 30 O C

(Heath 1963).

I n a study i n southeast Alaska, out- m ig ra t i on o f c u t t h r o a t t r o u t peaked a t water temperatures between 4 t o 6 O C

and i n m i g r a t i o n began a t 10 t o 12 O C

and peaked a t 9 t o 10 O C (Jones 1977).

Substrate and Cover

There i s considerable v a r i a t i o n i n s u i t a b l e subst ra te s i z e (gravel diameter) f o r c u t t h r o a t t r o u t ; they have been observed spawning i n gravel o f 2 t o 5 cm (June 1981), 0.6 t o 10.2 cm (Hunter 1973), and 0.16 t o 0.64 cm (Hooper 1973). Hanson (1977) found 1- t o 4-year-o ld c u t t h r o a t t r o u t i n streams associated w i t h subst ra tes o f

5 t o 30 cm. I r v i n g and B jo rnn (1984) found t h a t s u r v i v a l o f c u t t h r o a t embryos increased as t h e percentage o f f i n e sediments decreased. The s i z e o f a d u l t c u t t h r o a t t r o u t a f f e c t s g rave l - s i z e s e l e c t i o n and t h e t a i l s o f poo ls i n smal l t r i b u t a r y streams a re u s u a l l y chosen f o r spawning (Johnston and Mercer 1976).

Cover f o r f i s h can be p rov ided by overhanging vegeta t ion , undercut banks, and submerged ob jec t s such as l ogs and rocks, as we1 1 as by water depth and tu rbu lence (Giger 1972; Bus ta rd and Narver 1975; Reiser and B jo rnn 1979). Cover p r o t e c t s t h e f i s h from d is tu rbance and p r e d a t i o n and a l s o p rov ides shade. The biomass o f c u t t h r o a t t r o u t i n streams increases w i t h t h e amount o f cover p resen t (Wesche 1974; Lantz 1976; N icke lson and Re isenb ich le r 1977).

D isso lved Oxygen

Doudorof f and Shumway (1970) repo r ted t h a t salmonids t h a t hatched a t 1 ow d i sso l ved-oxygen 1 eve l s tended t o be weak and smal l , t o develop s low ly , and t o show increased abnor- mal i t i e s . Cu t t h roa t t r o u t general l y avo id water w i t h l e s s than 5 mg/l o f d i sso l ved oxygen i n t h e summer (T ro jna r 1972; Sekul i ch 1974). Doudorof f and Shumway (1970) a1 so demonstrated t h a t b o t h swimming speed and growth r a t e s o f salmonids dec l i ned as d i sso l ved-oxygen 1 eve l s decreased.

T u r b i d i t y

According t o Reiser and B jo rnn (1979), salmonid f i s h e s cease movement o r m i g r a t i o n i n streams w i t h very h i gh s i l t loads (>4,000 mg/l). Because more r a d i a t i o n i s absorbed by t u r b i d water t han by c l e a r water, a thermal b a r r i e r t o movement and m i g r a t i o n may develop (Reiser and B jo rnn 1979). Bachman (1958) repo r ted t h a t c u t t h r o a t t r o u t a d u l t s stopped feed ing and moved t o cover a t t u r b i d i t i e s above 35 ppm.

Suspended sediment l e v e l s exceeding 103 ppm, combined w i t h d i sso l ved oxygen concent ra t ions l e s s t han 6.9 mg/l and v e l o c i t i e s i n t h e redd o f l e s s than 55 cm/h, can reduce egg s u r v i v a l t o below 10% (Bianchi 1963).

F r y emergence from t h e g rave l may be h indered by excessive sand and s i l t (Reiser and B jo rnn 1979). These cond i t i ons may a l s o l i m i t t h e p roduc t i on o f ben th i c i n v e r t e b r a t e s necessary f o r optimum r e a r i n g of j u v e n i l e f i s h (Reiser and B jo rnn 1979).

Water V e l o c i t y

F ry i n stream environments p r e f e r shal lower water and s lower v e l o c i t i e s than o the r c u t t h r o a t t r o u t l i f e stages ( M i l l e r 1957; Horner and B jo rnn 1976). V e l o c i t i e s o f l e s s than 0.30 m/s a r e p r e f e r r e d and t h e optimum i s l e s s than 0.08 m/s (Horner and B jo rnn 1976). Juveni 1 e c u t t h r o a t t r o u t i n streams a re most o f t e n found i n v e l o c i t i e s o f 0.25 t o 0.50 m/s (T.E. Nickelson, unpubl. data). Thompson (1972) found young-of-the-year and 1-year-01 d cu t - t h r o a t t r o u t i n water v e l o c i t i e s o f 0.5 t o 0.6 m/s. Hanson (1977) found 1-year -o ld f i s h i n v e l o c i t i e s aver- aging 0.10 m/s. Hanson (1977) a l s o found 2-, 3-, and 4-year -o ld c u t t h r o a t t r o u t a t mean v e l o c i t i e s o f 0.14, 0.20, and 0.14 m/s, r e s p e c t i v e l y .

Cu t t h roa t t r o u t have been found spawning i n smal l streams w i t h f l o w r a t e s as low as 0.01-0.03 m3/s (Dimick and M a r r y f i e l d 1945; Wyatt 1959; Moring and Youker 1979). Spawning may occur i n se lec ted areas o f l a r g e streams (Moring and Youker 1979). Cu t t h roa t t r o u t spawning occurs i n water v e l o c i t i e s rang ing from 0 .11 t o 0.56 m/s i n Washington (Hunter 1973) and 0.30 t o 0.90 m/s i n no r the rn Cal i f o r n i a (Hooper 1973).

Coastal c u t t h r o a t t r o u t p r e f e r t o spawn i n t he headwater t r i b u t a r i e s o f l a r g e r streams. Summer water f l o w r a t e s i n these n a t a l creeks seldom

exceed 0.28 m3/s du r ing low f l o w and r e a r i n g h a b i t a t (Moring and Lantz most average 0.12 m3/s (Johnston 1974; Moring 1975). 1982).

Water Depth

Cut th roat t r o u t spawn a t the t a i l ends o f pools a t depths as shal low as 10-15 cm (June 1981) o r as deep as 1 m (Johnston and Mercer 1976). Hunter (1973) found c u t t h r o a t spawning i n water 6-40 cm deep. June (1981) found some redds i n r i f f l e areas.

I n streams, a d u l t c u t t h r o a t t r o u t a re found i n the deeper poo ls and slower v e l o c i t y water, wh i l e t he f r y are found i n shal lower, f a s t e r areas ( G r i f f i t h 1972; June 1981).

Timber Harvest

Logging p rac t i ces can d i r e c t l y and i n d i r e c t l y change the phys ica l environments i n t he small headwater streams t h a t are the important spawning and r e a r i n g areas f o r coas ta l c u t t h r o a t t r o u t . Such changes can s i g n i f i c a n t l y a l t e r c u t t h r o a t t r o u t populat ions (Ha l l and Lantz 1969; Moring 1975; Lantz 1976). Poor logg ing p r a c t i c e s i n t he v i c i n i t y o f small streams can cause a v a r i e t y o f changes t h a t are de t r imenta l t o t h e c u t t h r o a t t r o u t . These i nc lude (1) an increase i n both the maximum and the d iu rna l f l u c t u a t i o n o f t h e water temperature (Hal 1 and Lantz 1969; Moring 1975; R ing le r and Hal 1 1975; Chamberlin 1982); (2) decreases i n d isso lved oxygen i n bo th sur face and i n t r a g r a v e l water (Ha l l and Lantz 1969; Moring 1975; R ing ler and Hal 1 1975; Chamberl i n 1982) ; (3) increased sedi- ments i n t he stream ana changes i n t he amount o f f i n e s present i n t he gravel (Ha l l and Lantz 1969; Moring 1975; Chamberlin 1982); (4) increased stream f l o w r e s u l t i n g i n v e l o c i t y and depth changes (Moring 1975; Chamberl i n 1982); (5) a l t e r a t i o n o f t h e amount o f woody debr is i n t h e stream causing pH changes (Chamberlin 1982); and (6) l oss o f t e r r e s t r i a l and aquat ic vegeta t ion used as food sources and

THE FISHERY

Angl ing f o r sea-run c u t t h r o a t t r o u t occurs i n bo th the marine and f resh- water environments (Hisata 1973; Johnston and Mercer 1976; Washington 1977; Mercer 1982). Although on l y 1 i m i t e d data are a v a i l a b l e on t o t a l annual harvest and f i s h i n g pressure, t he sea-run c u t t h r o a t t r o u t f i s h e r y represents an important component o f t he spo r t f i s h e r i e s o f t he P a c i f i c Northwest.

Angler surveys conducted by the U.S. Nat ional Marine F i she r ies Serv ice i n 1974 i n the marine area o f Puget Sound, Washington, i nd i ca ted t h a t c u t t h r o a t t r o u t were second on ly t o salmon i n p o p u l a r i t y among sa l twater anglers (Johnston and Mercer 1976). An e a r l i e r Washington Department o f Game survey i n 1964 showed a t o t a l o f 43,700 anglers f i shed f o r anadromous c u t t h r o a t i n marine areas o f Washington State (Johnston and Mercer 1976). The average per c a p i t a expenditure was $25 per day i n 1974, w i t h t he t o t a l value t o t he S t a t e ' s economy est imated a t $8,850,000 per year. Although t h i s data may have been biased, t he re i s no reason t o be l i eve a dec l i ne i n p a r t i c i p a t i o n has occurred i n t h e marine f i s h e r y . The t o t a l p a r t i c i p a t i o n i n and value o f t he f reshwater f i s h e r y f o r anadromous c u t t h r o a t i n Washington has never been eval uated. However, over 1,800 man-days were expended i n 1970 pursuing c u t t h r o a t t r o u t i n sa l twater on southern Hood Canal (Johnston and Mercer 1976).

I n Oregon i n 1972, anglers caught an est imated 126,000 a d u l t c u t t h r o a t , 86% from coasta l streams and 14% from the Columbia R iver and i t s t r i b u t a r i e s (Johnston and Mercer 1976). They est imated t h e annual value o f t he stream c u t t h r o a t t r o u t f i s h e r y t o Oregon's economy was $3,750,000, based

on an average p e r c a p i t a expend i t u re es t ima ted a t $30 pe r day i n Washington S t a t e by Ql i v e r e t a l . (1975). The p r o j e c t e d c a t c h i n Washington and i t s impact on t h e S t a t e ' s economy has been assumed t o be g r e a t e r t han i n Oregon due t o g r e a t e r numbers o f streams i n Washington S t a t e t h a t c o n t a i n c u t - t h r o a t t r o u t and a l a r g e r human p o p u l a t i o n c l o s e t o these streams (Johnston and Mercer 1976).

T i p p i n g (1981) i n d i c a t e d t h a t 84% o f a l l sea-run c u t t h r o a t t r o u t were caught by ang le r s t a r g e t i n g on them, w h i l e 16% were caught i n c i d e n t a l t o salmon and s t e e l head. Most angl i ng e f f o r t was by p l unke rs , w i t h boa te r s second, and d r i f t f ishermen t h i r d (T i pp i ng and Sp r i nge r 1980; T i p p i n g 1981). Q v e r a l l c u t t h r o a t t r o u t a n g l i n g e f f o r t i s h i g h e s t i n August (T i pp i ng and Sp r i nge r 1980), b u t t h e h i g h e s t c a t c h was i n t h e f i r s t 2 weeks o f September (T i pp i ng 1981). Most ang le r s caught one f i s h o r l e s s p e r t r i p (T i pp i ng and Sp r i nge r 1980; T i p p i n g 1981). The m a j o r i t y o f f i s h caught were s e x u a l l y mature (T i pp i ng 1981).

The amount o f a n g l e r p a r t i c i p a t i o n w i l l 1 i k e l y double between 1972 and 1990 i n Oregon and a s i m i l a r t r e n d may occur i n Washington (Johnston and

Mercer 1976). The va l ue o f t h e c u t t h r o a t f i s h e r y t o b o t h Oregon and Washington economies i s expected t o i n c rease a long w i t h f i s h i n g p ressure ; however, i t i s a n t i c i p a t e d t h a t t h e n a t i v e s tocks o f sea-run c u t t h r o a t w i l l n o t i nc rease and may dec l Sne due t o h a b i t a t degrada t ion and p o s s i b l e o v e r f i s h i n g (Johnston and Mercer 1976). New r e s t r i c t i v e r e g u l a t i o n s (2 f i s h p e r day and 12 - i nch minimum s i z e ) w i t h i n B r i t i s h Columbia and Washington, which were des igned t o i n c rease spawner escapement, have s i g n i f i c a n t l y inc reased t h e abundance o f o l d e r , l a r g e r f i s h i n many watersheds (J. M. Johnston, unpubl . data) . Johnston (1980) i n d i c a t e d t h a t a t w o - f i s h 1 i m i t i n t h e S t i l laguamish R i v e r would reduce t h e t o t a l ha r ves t o f sea-run c u t t h r o a t t r o u t by about 20%. A 14 - i nch minimum s i z e l i m i t on sea-run c u t t h r o a t caught i n a1 1 mar ine wate rs and s e l e c t e d f r eshwa te r streams was p u t i n f o r c e i n Washington S t a t e i n 1987.

Concurrent w i t h h a b i t a t p r o t e c t i o n , agencies r espons ib l e f o r t h e manage- ment o f sea-run c u t t h r o a t popu la t i ons have a t tempted t o spread t h e harves t - a b l e p o r t i o n o f t h e s tocks t o more ang le r s by imposing r e s t r i c t i o n s on c a t c h and possess ion, s i z e , season, and gear.

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Moring, J. R. , and R. L. Lantz. 1975. The Alsea watershed study: P a r t I-- b i o l o g i c a l s tud ies . Oregon Dep. F i sh W i l d l . , F i s h Res. Rep. 9. 66 pp.

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iOZ72 -101

Washington Cooperative F ishery Research Un i t Un i ve r s i t y o f Washington Seat t le , WA 98195

REPORT DOCUMENTATION 1. 2.

PAGE l ~ i o l o g i c a l Report 82 (11.86)*( I

6. Title and Subtitle

Species P ro f i l e s : L i f e H i s t o r i es and Environmental Requirements o f Coastal Fishes and Inver tebrates (Pac i f i c Northwest)--Sea-run cu t t h roa t t r o u t

7. Authods)

i i l b e r t B. Pauley, Kevin Oshima, Karen L. Bowers, and Gary L. Thomas 9. perf om in^ Organlxation Heme and Address

-- 12. Smnsorina Orgenlratlon Name end Addnss

U.S. Department o f the I n t e r i o r U. S. Army Corps o f Engineers F ish and W i l d l i f e Service Watarways Experiment S ta t i on Research and Development P.O. Box 631 Nat ional Wetlands Research Center Vicksburg, MS 39180 Washington, DC 20240

3. Recipient's Accession NO.

5 RePOR Oat*

January 1989

8. Perfomins Orgeniratlon Red. N,

10. PmjeetlTeshlWorh Unit No.

I

15. Supplementeq Notes

*U.S. Army Corps o f Engineers Report No. TR EL-82-4

LL Abatraa (Limit: 200 words)

Species p r o f i l e s are l i t e r a t u r e summaries o f the taxonomy, morphology, range, l i f e h i s t o r y , and environmental requirements o f coastal aquat ic species. They are designed t o a s s i s t w i t h environmental impact assessments. The sea-run cu t t h roa t t r o u t (Salmo c l a r k i c l a r k i ) i s anadromous and i s found i n most coastal streams from Southeast Alaska t o Northern Ca l i f o rn i a . A t h r i v i n g spor t f i she r y e x i s t s both i n these freshwater streams and i n protected marine waters. Many o f the small streams conta in ing cu t t h roa t t r o u t can be adversely a l t e red by poor t imber operations. Optimum temperature f o r incubat ing i s 10 t o 11 O C and eggs hatch i n 28-40 days. Optimum temperature f o r juven i les i s 15 O C and a b i l i t y t o swim i s l o s t a t about 28 O C . Adults p re fe r f a i r l y slow-moving water w i t h p l en t y o f cover. Spawning occurs i n small diameter gravel . L i ke steelhead t r o u t , they may r e t u r n from sa l twa te r t o spawn several t imes.

17. Document Anmlyais m. Oeacripton

Temperature Feeding hab i t s Estuar ies Trout Animal migrat ions L i f e cyc les

b. 1dentIfienlOp.n.Ended Terms

Sea-run cu t t h roa t t r o u t Coastal cu t t h roa t t r o u t Salmo c l a r k i c l a r k i ---

Ecologica l r o l e Environmental requirements Timber harvest

la Avahlablllty Statement 1 19. Security Class (This Remrtl 1 21. NO. of penes

( ~ o n m r l y NTIS-35) o e p a r t m d commerce

Unl imi ted d i s t r i b u t i o n Unc lass i f i ed

1 Unc lass i f i ed

2 1 -- a. price

em ANSI-739.lEl OPTIONAL FORM 272 (4-71

TAKE A PRIDE 212 Amerzcd

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As the Nation's principal conservation agency, the Department of the Interior has respon- sibility for most of our .nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, preserving thsenvironmentai and cultural values of our national parks and hlstorical places, and providing for the enjoyment of life through outdoor recreation. The Department as- sesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also has a major responsibility for American Indian reservation communities and for people who live in island territories under U.S. administration.