REFF2,QJCY CO'Dv 3 a -t .. ;

Do Not Remove from the Librsr,! U. S. Fish and Wildlife Service

Biological Report 82 ( 1 1.49) National Wetlands Research C e n k , TR EL-82-4 Apr i l 1988 700 Cajun Dome Boulevard

Lafcryette, Louisiana 70506

Species Profiles: Lit e Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Pacific Southwest)

CHINOOK SALMON

Coastal Ecology Group Fish and Wildlife Service Waterways Experiment Station U.S. Department of the Interior U.S. Army Corps of Engineers

B i o l o g i c a l Report 82( 11.49) TR EL-84-4 A p r i l 1986

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 Coastal F ishes and I n v e r t e b r a t e s ( P a c i f i c Southwest)

CHINOOK SALMON

Mark A. A l l e n and Thomas J. Hass ler C a l i f o r n i a Cooperat ive F i s h e r y Research U n i t

Humboldt S ta te U n i v e r s i t y Arca ta , CA 95521

P r o j e c t O f f i ce r John Parsons

Na t i ona l Coastal Ecosystems Team U.S. F i s h and W i l d l i f e Serv ice

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

Per f ormed For Coastal Ecology Group

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

Vicksburg, MS 39180

and

Na t i ona l Coasta l Ecosystems Team D i v i s i o n o f B i o l o g i c a l Serv ices

Research and Devel opment F i s h and W i l d l i f e Serv ice

U.S. Department o f t h e I n t e r i o r Washington, DC 20240

Th is s e r i e s shou ld be r e f e renced as f o l l o w s :

U.S. F i s h and W i l d l i f e Serv ice . 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 env i ronmenta l requ i rements o f coas ta l f i s h e s and i n v e r t e b r a t e s . U.S. F i s h W i l d 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 should be c i t e d as f o l l o w s :

A l len , M.A., and T.J. Hass le r . 1986. Species p r o f i l e s : l i f e h i s t o r i e s and env i ronmenta l requi rements o f coas ta l f i s h e s and i n v e r t e b r a t e s ( P a c i f i c Southwest ) - -ch inook salmon. U. S. F i s h W i l d l . Serv. B i o l . Rep. 82(11.49). U.S. Army Corps o f Engineers, TR EL-82-4. 26 pp.

PREFACE

Th i s spec ies p r o f i l e i s one o f a s e r i e s on coas ta l a q u a t i c organisms, p r i n c i p a l l y f i s h , o f spo r t , commercial , o r e c o l o g i c a l importance. The p r o f i l e s a r e designed t o p r o v i d e coas ta l managers, eng ineers , and b i o l o g i s t s w i t h a b r i e f comprehensive ske tch 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 env i ronmenta l requ i rements o f t h e spec ies and t o desc r i be how popu la t i ons o f t h e spec ies may be expected t o r e a c t t o env i ronmenta l changes caused by coas ta l development. Each p r o f i l e has sec t i ons on taxonomy, 1 i f e h i s t o r y , e c o l o g i c a l r o l e , env i ronmenta l requi rements, and economic impor tance, i f app l i cab l e . A t h r e e - r i ng b i n d e r i s used f o r t h i s s e r i e s so t h a t new p r o f i l e s can be added as t hey a r e prepared. Th i s p r o j e c t i s j o i n t l y p lanned and f i nanced by t h e U.S. Army Corps o f Engineers and t h e U.S. F i s h and W i l d l i f e Serv ice .

Suggest ions o r ques t ions r e g a r d i n g 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 h e f o l l o w i n g addresses.

I n f o r m a t i o n T r a n s f e r S p e c i a l i s t Na t i ona l Coasta l Ecosystems Team U.S. F i s h and W i l d l i f e Se rv i ce NASA-Sl idel 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 t e n t i o n : WESER-C Post O f f i c e Box 631 Vicksburg, MS 39180

CONVERSION TABLE

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

Mu1 t i p l y !Y To Obtain

m i l 1 lmeters (mn) cent imeters (cm) meters (m) k i 1 m e t e r s ( km)

2 square meters (m ) 10.76 square k i 1 m e t e r s (km2) 0.3861 hectares (ha) 2.471

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

lnches lnches f e e t mi1 es

square f e e t square m i l es acres

gal 1 on s cubic f e e t acre- f e e t

m i l l igrams (mg ) 0.00003527 ounces grams ( g ) 0.03527 ounces k i lograms ( k ) 2.205 pounds me t r i c tans q t ) 2205.0 pounds me t r i c tons 1.102 sho r t tons k i 1 ocal o r i e s (kca l ) 3.968 B r i t i s h thermal u n i t s

Cels ius degrees 1.8(OC) + 32 Fahrenhei t degrees

U.S. Customary t o Me t r i c

inches 25.40 inches 2.54 f ee t ( f t ) 0.3048 fathoms 1.829 m i l e s (m i ) 1.609 nau t i ca l m i les ( m i ) 1.852

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

ga l 1 ons (ga l ) cubic f e e t ( f t 3 ) acre- fee t

cunces (02) 28.35 pounds ( 1 b) 0.4536 sho r t tons ( t o n ) 0.9072 B r i t i s h thermal u n i t s (B tu ) 0.2520

m i l 1 irneters cent imeters meters meters k i lometers k i 1 m e t e r s

square meters hectares square k i lometers

1 i t e r s cubic meters cubic meters

grams k i 1 ograms me t r i c tons k i 1 ocal o r i es

Fahrenheit degrees 0.5556(OF - 32) Cels ius degrees

CONTENTS

Page

PREFACE ................................................................... iii CONVERSION TABLE .......................................................... i v ACKNOWLEDGMENTS ........................................................... v i

NOMENCLATURE/TAXONOMY/RANGE ............................................... 1 MORPHOLOGY/IDENTIFICATION AIDS ........................................ 1 REASON FOR INCLUSION IN SERIES ........................................ 3 L IFE HISTORY .............................................................. 3

Upst ream M i g r a t i o n ...................................................... 3 Spawning ................................................................ 4 Eggs and A l e v i n s ........................................................ 5 F r y and Smo l t s .......................................................... 6 Downstream M i g r a t i o n .................................................... 7 E s t u a r i n e Res idence ..................................................... 7 Oceanic Res idence ....................................................... 8

GROWTH .................................................................... 9 THE FISHERY ............................................................... 10 ECOLOGICAL ROLE ........................................................... 11

C o m p e t i t i o n ............................................................. 11 P r e d a t i o n ............................................................... 13 Food .................................................................... 13

ENVIRONMENTAL REQUIREMENTS ................................................ 13 Temperature ............................................................. 13 S a l i n i t y ................................................................ 14 ........................................................ D i s s o l v e d Oxygen 14 S u b s t r a t e ............................................................... 16 Depth ................................................................... 17 .......................................................... Water Movement 17 T u r b i d i t y ............................................................... 17 Heavy M e t a l s ............................................................ 18

LITERATURE CITED .......................................................... 19

ACKNOWLEDGMENTS

We are g r a t e f u l f o r reviews by Richard J. Hal lock and Kenneth A. Hashagen, Jr., C a l i f o r n i a Department o f F i s h and Game.

F i g u r e 1. Chinook salmon.

CH 1 NOOK SALMON

S c i e n t i f i c name . . . . . O n c o r h y n c h ~ tshawytscha (Wal baum) (F i gu re 1 ) .

P re fe r red common name . . . . Chinook salmon

Other common names . . . . King, k i n g salmon, t yee , qu inna t , s p r i n g salmon.

Class . . . . . . . . . . Oste ich thyes Order . . . . . . . . . . Salmoni formes Fami ly . . . . . . . . . . .Salmonidae

Geographic range: Spawning popu- l a t i o n s o f chinook salmon i n Nor th America are d i s t r i b u t e d f rom the Sacramento-San Joaquin R iver system i n c e n t r a l C a l i f o r n i a n o r t h t o Po in t Hope, Alaska. As ian popu la t i ons are d i s t r i b u t e d from Japan n o r t h t o t he Anadyr R i yer, USSR. I n t r o d u c t i o n s of young chinook salmon have es tab l i shed spawning popu la t i ons and f i s h e r i e s i n r i v e r s t r i b u t a r y t o South Is land , New Zealand, and t h e

U.S. Lau ren t i an Grea t Lakes. The major r i v e r s i n C a l i f o r n i a t h a t suppor t spawning runs of c h i nook salmon are shown i n F i gu re 2.

The f o l l o w i n g d e s c r i p t i o n s were taken from McConnell and Snyder (19721, Har t (19731, and Moyle (1976). F i n r ays : Dorsal 10-14, anal 13-19, p e l v i c 10-11, and pec to ra l 14-19. The caudal f i n i s moderate ly forked; ad ipose i s s t o u t and prominent; a f r ee - t i pped f l e s h appendage i n s e r t s j u s t above t h e p e l v i c . Cyc lo i d scales, 130-165 pored scales on l a t e r a l l i n e , 131-158 i n rows above. Number of b ranch ios tega l r ays each s i d e o f jaw, 13-19; g i l l r ake rs rough and w i d e l y spaced, 6-10 on lower h a l f o f f i r s t g i l l arch; p y l o r i c caeca, 120-185.

kd Coastal Distribution

P A C I F I C O C E A N

Figure 2. The major r i v e r s i n the P a c i f i c Southwest t h a t support spawning runs o f chinook salmon.

The a d u l t has prominent i r r e g u l a r b lack spots on back, upper s ides, dorsal f i n , and bo th lobes o f caudal f i n . Spawni ng ma1 es develop moderately hooked jaws and dark 01 i v e t o red sk in. Lower jaw gum-line i s s o l i d b lack. Juven i les are c loses t i n appearance t o coho salmon (g. ,k isu tch) , b u t a re d i s t i ngu i shed by 6 t o 12 p a r r marks t h a t are wider than t h e i n t e r s t i c e s ; t he anal f i n i s unpigmented between rays and the a n t e r i o r t i p i s no t d i s t i n c t l y elongated; the adipose i s pigmented on upper sur face, c l e a r below; and t h e p y l o r i c caeca count i s d iagnos t i c (>120, bu t (90 i n coho salmon. )

REASON FOR INCLUSION I N SERIES

The ch i nook salmon supports valuable commercial and spor t f i s h e r i e s i n the P a c i f i c Southwest. This species accounted f o r over 69% of the salmon caught along the C a l i f o r n i a coast from 1971 through 1983, according t o t he P a c i f i c F ishery Management Counci 1 (PFMC 1984). Chinook f r y and smolts spend a p o r t i o n o f t h e i r e a r l y 1 i f e i n es tua r ies where growth i s rap id .

LIFE HISTORY

Upstream M ig ra t i on -

Chinook salmon spawning runs i n the Sacramento-San Joaquin River system produce over 50% of the annual ocean harvest o f chinook salmon i n C a l i f o r n i a (PFMC 1984). Runs i n the Sacramento R iver above the Red B lu f f D i ve rs ion Dam are composed o f f o u r popu la t ions , d i v i d e d as fo l l ows (1971-81 means): f a l l 54%, l a t e fa1 1 14%, w i n t e r 2l%, and sp r i ng 11% (Reavi s 1983).

The separat ion o f ch i nook salmon spawning populat ions i s based on the t imes o f the upstream m ig ra t i on o f adu l ts , spawning, and the downstream

m ig ra t i on o f j uven i l es (F igure 3 ) . External physical appearance, t ime o f gonadal development, and l o c a t i o n o f spawning grounds are add i t i ona l factors. Chinook salmon runs i n the f a l l and l a t e f a l l spawn i n the mainstem or t r i b u t a r i e s s h o r t l y a f t e r they reach t h e i r spawning grounds. Those i n the w in ter and spr ing runs may remain i n deep pools near t h e i r spawning grounds fo r as long as 5 months before t h e i r eggs r i p e n and spawning begins (Hal lock and Fry 1967).

Terminal dams i n the Sacramento- San Joaquin River system (F igure 2) , which lack fish-passage f a c i l i t i e s , have a l t e red the r e l a t i v e composit ion of the f o u r spawning populat ions of chinook salmon. U n t i l t he construc- t i o n o f Shasta Dam i n 1942, t h e w i n t e r r u n o f chinook salmon spawned i n upper Sacramento R iver t r i b u t a r i e s and was be l ieved t o be o f minor importance. A f t e r 1942, water re leased from the dam created favorab le spawning tem- peratures i n t he mai nstem Sacramento R iver f o r wi n te r - run chinook salmon and t h e i r numbers increased (Sl a t e r 1963). Spring-run chinook salmon,

Figure 3. Adul t migra t ion , spawning, and j u v e n i l e downstream m ig ra t i on o f chinook slamon i n the Sacramento R ive r a t Red B l u f f D ivers ion Dam, C a l i f o r - n ia ; c i r c l e s i n d i c a t e peak a c t i v i t y (Hal l ock 1983).

- - - 5 LL

- - - z 2 2 E I- 5 < d a ; 2 z = 2 _

b

a (0

- - ........................................................................................... - .......................................................................................... P = = a m m = - - ..........................................................................................

<mJm s o m e yearlnngs

.c ' A ' M ' J J A S O N O J F M A M J J A S O N D

I

MONTH - ~ d u l l m # g r a t i o n

-4Ib= J u v e n i l e

- Spawning

d o w n s t r e a m mngretlon

however, were unable t o adapt t o t he 1 oss o f t h e i r headwater spawning grounds and t h e i r numbers decreased.

The cons t ruc t i on o f F r i a n t Dam on the San Joaquin River i n 1939 blocked the spr ing-run o f chinook salmon from t h e i r spawning grounds and they have a1 1 bu t disappeared (Hal l ock e t a1 . 1970; C a l i f o r n i a Department o f F i s h and Game 1971). Now (1971-84) o n l y a f a l l - r u n popu la t i on remains and averages o n l y 10% o f t h e f a l l - r u n o f chinook salmon i n t h e Sacramento R i ve r (F igure 4).

Spr i ng-run ch i nook salmon a1 so ascend the Eel and Klamath River systems t o spawn but have con t r i bu ted less than 5% o f a l l chinook salmon produced i n Cal i f o r n i a. Chi nook salmon spawning runs have decreased i n a1 1 C a l i f o r n i a r i v e r s , especia l1 v i n t h e Sacramento and San Joaquin Rivers (F igure 4).

The re lease o f gonadal o r thy - r o i d hormones i n a d u l t salmon may s t imu la te upstream m ig ra t i on by mod i fy ing f i s h behavior i n response t o ex te rna l va r i ab les t h a t i n f 1 uence m i g r a t i o n (Hoar 1953). An i ncrease i n t he volume o f stream f l o w i s the

- < 5004 Sacramenlo River syslem

most f r e q u e n t l y c i t e d environmental s t imu lus t o upstream migra t ion , b u t t h i s r e l a t i o n i s most ev iden t i n small r i v e r s (Banks 1969). Changes i n atmospheric pressure, water t u r b i d i t y , water temperature, and d i sso l ved oxygen are a l s o known t o i n f l u e n c e upstream migra t ion .

Low d i sso l ved oxygen and h igh water temperatures i n h i b i t e d upstream movement o f f a l l - r u n chinook salmon i n the San Joaquin River (Hal lock e t a l . 1970). Most a d u l t chinook salmon migra te upstream dur ing the day (Needham e t a1 . 1940; Banks 1969). Fa1 1 -run chinook t y p i c a l l y migra te upstream a t a r a t e o f 5 t o 14.5 kmlday (Gray and Haynes 1979; H e i f e t z 1982).

The homing o f salmon t o t h e i r parent stream a f t e r en te r i ng f reshwater i s we l l documented and i s a t t r i b u t a b l e t o o l f a c t o r y cues t h a t are s p e c i f i c f o r each l o c a t i o n and are " learned" by the j u v e n i l e salmon s h o r t l y before they migra te t o the sea (Hasler and Wisby 1951; Hasler and Scholz 1983). Genetic h i s t o r y may a1 so i n f 1 uence homing success (Barns 1976 1.

Salmon do not u s u a l l y feed a f t e r en te r i ng f reshwater and severe atrophy o f the d i g e s t i v e system se ts i n before spawning begins .

-.. 5 4 1111111 San Joaauin River svstem

Spawning --

F igure 4. The est imated number o f fa1 1-run chinook salmon (may i nc lude some spr ing-run f i s h ) t h a t returned y e a r l y t o the Sacramento and San Joaquin Rivers t o spawn i n 1953-83 (da ta from Tay lo r 1974; Reavis 1983; PFMC 1984).

The female chinook salmon usu- a l l y chooses a nes t i ng s i t e i n gravel deposi ts a t the lower l i p o f a pool j u s t above a r i f f l e (Burner 1951; Br iggs 1953). The female makes a redd (an area conta in ing several i n d i v i d u a l nes ts ) by t u r n i n g on her s i de and repeated ly f l e x i n g her body and t a i l t o force gravel and f i n e sediment i n t o t he water column; these sediments are deposi ted a sho r t d is tance downstream. The completed nest forms an oval de- pression w i t h a mound o f grmrel 1 ocated immedi ate1 y downstream.

Dur i ng spawning, a dominant male salmon accompanies t h e female and agg ress i ve l y chases away o t h e r males a t t e m p t i n g t o e n t e r t h e redd area. The eggs and sperm a r e re leased i n t o t h e nes t by t h e female and male s imu l taneous ly . U s u a l l y one o r more males w i 11 p o s i t i o n themselves a l ongs ide t h e female oppos i t e t h e dominant male and re l ease sperm. By t h e end o f t h e spawning, as many as 10 t o 12 male salmon may have at tempted t o spawn w i t h a s i n g l e female (B r i ggs 1953; Vronsk iy 1972).

A f t e r t he eggs a re re leased, t h e female u s u a l l y moves j u s t upstream and repeats the nest b u i l d i n g and the spawning a c t . The f e r t i l i z e d eggs are b u r i e d 20 t o 60 cm below t h e g rave l sur face w i t h t he excava t ion mater i a1 f rom t h e new nest (Br igas 1953; Vronsk iy 1972). The female w i l l repea t t he process severa l t imes before spawning i s completed. Each completed redd may con ta i n severa l nes ts ; t h e o v e r a l l s i z e o f t he redd i s d i r e c t l y r e l a t e d t o t h e s i z e o f f i s h and i n v e r s e l y r e l a t e d t o t h e s i z e of t h e s u b s t r a t e p a r t i c l e s , water v e l o c i t y , and d e n s i t y o f spawners (Burner 1951; Vrons k i y 1972). Female ch inook salmon sometimes d i g f a l s e redds (bu t do n o t d e p o s i t eggs t he re ) be fo re and a f t e r t hey b u i l d t r u e redds (Br iggs 1953).

Each female may spawn over a p e r i o d o f 5 t o 14 days. U n l i k e females o f o t h e r salmon species, female ch inook salmon may defend t h e redd f rom i n t r u d i n g females f o r 5 t o 9 days a f t e r spawning (B r i ggs 1953; Vrons k i y 1972).

A f t e r spawning, the salmon d e t e r i o r a t e r a p i d l y , e x h i b i t i n o l a r g e open wounds and heavy funga l i n f e c t i o n . L i f e e x ~ e c t a n c v a f t e r spawning i s 2 t o 4 weeks (B r i ggs 1953).

Eaas and A lev i ns

Fecund i ty v a r i e s g r e a t l y among c h i nook salmon of d i f f e r e n t popu la t ions . For example, f e c u n d i t y o f f a 1 1 - run c h i nook salmon averages 3,634 eggs pe r female i n t h e Klamath R i ve r b u t 7,295 eggs i n Sacramento R i ve r f i s h . D i f f e r e n c e i n female s i z e a lone cannot account f o r t h e v a r i a t i o n i n f e c u n d i t y (Healey and Heard 1984).

Chinook salmon eggs a r e la rge : 6.3 t o 7.9 mm i n d iameter (Rounse fe l l 1957) and 0.35 t o 0.40 grams i n we igh t ( L e i t r i t z and Lewis 1980).

The l enq th o f t i m e r e a u i r e d f o r ha t ch ing i s i n v e r s e l y r e l a t e d t o water temperature. Chinook salmon eggs have been s u c c e s s f u l l y incubated and hatched a t water temperatures of 4' t o 16' C; however, lower temperatures can be t o l e r a t e d i n t h e l a t e r stages o f embryonic development (Combs and Burrows 1957; Combs 1965; P iper e t a l . 1982).

Chinook salmon eggs a re p a r t i c u l a r l y vu l ne rab le t o shock i n j u r y . I n j u r y can r e s u l t f rom g rave l movement caused by bottom scou r i ng, mechanical impact ion, o r superimposed spawning a c t i v i t y . Other causes of egg m o r t a l i t y a re low d i sso l ved oxygen, h igh concent ra t ions of t o x i c chemicals, excess i ve l y h i gh water temperatures, i n f e s t a t i o n s w i t h fung i or 01 i gochaetes, p reda t i on by i n s e c t s o r f i s h , and heavy sedimentat ion. Under poor c o n d i t i o n s t he m o r t a l i t y o f eggs may be as h i gh as 95% (Wales and Coots 1954; Gangmark and Bakkala 1960). Under i d e a l c o n d i t i o n s t h e m o r t a l i t y o f t he eggs may be as low as 10% (Br iggs 1953).

A f t e r ha tch ing , a l e v i n s (yo1 k- sac l a r v a e ) remain i n t h e g rave l i n t e r s t i c e s f o r a month o r longer , d u r i n g which t ime t hey e x h i b i t t h e f o l l o w i n g t h r e e major d i s t r i b u t i o n a l phases : a deeper submergence, a r e s t i n g per iod, and an upward emergence (D i 11 1969 1. Sal moni d

a l e v i n s a re n e g a t i v e l y p h o t o t a c t i c and p o s i t i v e l y g e o t a c t i c and t h i g m o t a c t i c ; these c h a r a c t e r i s t i c s serve t o encourage f u r t h e r submergence i n t o t h e g rave l and p reven t premature emergence (Godi n 1981). A f t e r deeper submer- gence, a l e v i n s remain r e l a t i v e l y i n a c t i v e un less f o r c e d t o d i spe rse i n response t o excess ive l e v e l s o f carbon d i o x i d e o r me tabo l i c waste ( D i l l 1969), o r t o a v o i d d e s i c c a t i o n d u r i n g low f l o w (Fas t e t a l . 1981).

As t h e yo1 k sac i s absorbed, a1 ev i ns develop p o s i t i v e r h e o t a c t i c and p h o t o t a c t i c responses and begin an upward m i g r a t i o n i n t h e g rave l ( D i l l 1969 1. I n t r a - g r a v e l movement o f a l e v i n s i s governed by g rave l s ize, i n t e r s t i t i a l spacing, r a t e o f water f low, d i sso l ved gases, and water temperature (D i 11 1969; Godin 1981 1.

F r y and Smolts .- .--- -

Chi nook salmon f r y usual 1 y emerge from the g rave l a t n i gh t , probably as an a n t i p r e d a t i o n measure (Bams 1969 1, and spend 1 t o 18 months i n f reshwater . A f t e r emerging, most chinook salmon f ry immediate ly d isperse downstream, p o s s i b l y because o f t h e i r new nondemersal h a b i t s and l o s s o f v i s u a l con tac t w i t h t h e stream s u b s t r a t e (Reimers 1973). D iu rna l d i s p e r s i o n has been observed d u r i n g increases i n water t u r b i d i t y and temperature ( R u t t e r 1904; Thomas 1975). A f t e r emergence, t h e f r y develop n e u t r a l buoyancy, begin exogenous feeding, and develop s o c i a l behavior (Bams 1969 1.

Chinook salmon f r y i n streams change h a b i t a t s as t hey grow o lde r . L i s t e r and Genoe (1970) genera l i zed changes i n o rder as fo l lows : " i n i t i a l h i d i ng , p o s s i b l y i n t h e gravel ; assoc ia t i on w i t h bank cover; appearance a long open shore1 i nes; and f i n a l l y , movement i n t o h iqher v e l o c i t y l o c a t i o n s a long t h e s t ream margin o r f a r t h e r ou t f rom shore." A f t e r t h e i n i t i a l h i d i n g per iod, chinook salmon f r y seek f i n e subs t ra tes and low water

v e l o c i t i e s , p r o g r e s s i v e l y moving i n t o deeper, f a s t e r , and r o c k i e r h a b i t a t s ( L i s t e r and Genoe 1970; Everest and Chapman 1972). Overw in te r ing sp r i ng - r u n chinook j u v e n i l e s h i d e under l a r g e rocks and debr is , a h a b i t a t s h i f t apparen t l y t r i g g e r e d by low water temperature (Chapman and B jo rnn 1969).

As t h e f ry beg in t o smoltl, t hey become s i l v e r y and sl immer and change t h e i r behav io r ; t h e i r t e r r i t o r i a l i n s t i n c t s break down, and t hey u s u a l l y emigra te i n schools downstream t o t h e ocean.

The osmoregulatory changes t h a t a l l o w t o l e r a n c e o f s a l t w a t e r a r e somewhat more complex i n chinook salmon than i n coho salmon o r s t e e l - head t r o u t (Salmo a i r d n e r i ) (Na t i ona l Mar ine F i s h ~ S b 9 7 9 - Zaugg 1981). U n l i k e t h e f r y o f o t h e r salmonids, those o f chinook salmon t o l e r a t e h i gh l e v e l s o f serum c h l o r i d e s and a re ab le t o r a p i d l y acc l imate t o h i gh s a l i n i t i e s . As t h e f r y age i n f reshwater , t h e i r t o l e r a n c e t o s a l i n i t y gradual l y i ncreases , and some e n t e r e s t u a r i e s w i t h o u t f i r s t deve lop ing t h e morphologica l char- a c t e r i s t i c s o f a smo l t (Hoar 1976). The degree o f s a l i n i t y t o l e rance depends somewhat on p r i o r acc l ima t i on , b u t f i s h s i z e and growth r a t e have been i d e n t i f i e d i n severa l s t u d i e s as f a c t o r s a f f e c t i n g s a l i n i t y t o1 erance. The s a l t w a t e r t o l e r a n c e o f l a r g e r f i s h o f a g i ven age i s known t o exceed t h a t o f sma l le r ones. Ewing e t a l . (1980), who moni tored g i 11 (~a+-K ' ) - ATPase a c t i v i t y as an i n d i c a t o r o f seawater readiness, found a c t i v i t y t o be lower among s lower-growing f i s h ; f a s t e r - growing f i s h had e i t h e r a more f u l l y f unc t i ona l osmoregul a t o r y system o r

lSmol t i s a s i l v e r y j u v e n i l e , t o l e r a n t o f seawater, m ig ra t i ng toward t h e ocean; f ry may l i v e i n e s t u a r i e s w i t h moderate s a l i n i t i e s , b u t genera l l y do n o t e n t e r t h e ocean. A p a r r i s a p re -smo l t s tage w i t h v e r t i c a l ba rs ( p a r r marks) on t h e s ides.

one t h a t was capable o f f a s t e r a c c l i m a t i o n t o h i ghe r s a l i n i t i e s (Wagner e t a l . 1969). Most i n v e s t i - g a t o r s agree t h a t t h e parr -smol t t r a n s f o r m a t i o n i n v o l v e s an endogenous rhy thm a f f e c t e d by f i s h s i z e and growth r a t e and env i ronmenta l cues t h a t i n c l u d e temperature, photoper iod, and l u n a r c y c l e (Ewing e t a l . 1979; Grau 1981 1.

Downstream M i g r a t i o n

J u v e n i l e ch inook salmon fo rm two ma jo r groups ( G i l b e r t 1913): those t h a t m i g r a t e t o t h e ocean e a r l y i n t h e i r f i r s t yea r o f l i f e (ocean- type) and those t h a t ove rw in te r i n f r e s h - water before e n t e r i n g t h e ocean (s t ream- type) . Fa1 1 - run ch inook s a l - mon a re t y p i c a l l y ocean-type and emig ra te downstream t o e s t u a r i e s as f r y s h o r t l y a f t e r t h e y emerge o r as smol ts (Reimers 1973; K j e l s o n e t a l . 1982). J u v e n i l e ch inook salmon o f t h e sp r i ng - run c h a r a c t e r i s t i c a l l y a re s t ream-type and emig ra te as year1 i ngs i n e a r l y s p r i n g ( S c h a f f t e r 1980). Win te r - run ch inook salmon f r y emerge i n t h e summer and emig ra te d u r i n g f a 1 1, when t h e y a re 4 t o 7 months o l d ( S l a t e r 1963). The pe r i ods of peak abundance o f m i g r a t i n g j u v e n i l e c h i - nook salmon i n t h e Sacramento R i ve r a re shown i n F i g u r e 3.

Chinook salmon j u v e n i l e s usual l y emig ra te i n t h e upper 2 m o f water i n d a y l i g h t , bu t swim deeper and d i s p e r s e a f t e r dark (CDFG 1975; Scha f f t e r 1980). The l a r g e r m ig ran t s t end t o concen t ra te i n midst ream where c u r r e n t v e l o c i t i e s a re g r e a t e s t (Scha f f t e r 1980). As s p r i n p progresses, t h e v e r t i c a l d i s t r i b u t i o n o f emigrants i s inc reased as t h e y d i s p e r s e and i n h a b i t deeper water (Wickmi r e and Stevens 1971). Increases i n s t reamf low and t u r b i d i t y a l s o have been observed t o i n c rease t h e v e r t i c a l and h o r i zon ta l d i s t r i b u t i o n o f m ig ran t s (Ha l l ock and Van Woert 1959). F r y m i g r a t e s lower than smol ts , a c h a r a c t e r i s t i c a t t r i b - u t a b l e t o t h e i r p re fe rence o f s lower v e l o c i t y streambank areas o r t h e i r

o r i e n t a t i o n ; t hey f ace upstream, whereas smol t s swim downstream ( S c h a f f t e r 1980). Es t imates of t h e m i g r a t i o n r a t e s o f f r y and smo l ts average 1.6 kmlday i n t h e mainstream ( R u t t e r 1904; Wickmire and Stevens 1971; K j e l s o n e t a l . 1982). The t ime o f year, water temperature, stream- f l ow , and f i s h s i z e a re a l l f a c t o r s i n f l u e n c i n g t h e t ime and speed of downstream m i g r a t i o n .

Es tua r i ne Residence

Severa l e a r l y l i f e h i s t o r y p a t - t e r n s o f f a l l - r u n ch inook salmon i n a c o a s t a l Oregon r i v e r were r e p o r t e d by Reimers (1973). Most f i s h emig ra ted i n t o t h e e s t u a r y i n t h e s p r i n g as f r y 2 t o 3 months o l d (50-69 mm l o n g ) . Some f r y en te red t h e ocean i n mid- summer, b u t o t he r s remained i n t h e es tua r y an a d d i t i o n a l 2 t o 4 months and en te red t h e ocean i n t h e f a 1 1 (90 t o 119 mm long) . From sca le a n a l y s i s o f r e t u r n i n g a d u l t s , Reimers (1973) conc luded t h a t t h e s u r v i v a l o f f i s h t h a t remained i n t h e e s t u a r y u n t i l f a l l was g r e a t e r t han t h a t o f m ig ran t s t h a t l e f t t h e e s t u a r y i n mid-summer.

O ther j u v e n i l e ch inook salmon m i g r a t i o n p a t t e r n s , acco rd i ng t o Reimers (1973), i n c l u d e f i s h t h a t go d i r e c t l y i n t o t h e ocean f rom f r esh - wa te r . Newly emerged f ry may d i r e c t l y e n t e r t h e ocean; j u v e n i l e s (70-85 mm l ong ) someti~nes pass d i r e c t l y i n t o t h e sea du r i ng f a l l f r e s h e t s ; and year - l i n g s (100-130 nm l ong ) may e n t e r i n t h e sp r ing .

Two p r i n c i p a l movements o f j u v e n i l e f a 1 1 - run ch inook salmon i n t o t h e Sacramento-San Joaquin Es tuary ( t h e D e l t a and Suisun, San Pablo, and San Franc isco Bays) have been i d e n t i f i e d ( K j e l s o n e t a l . 1982). F r y (40-50 mm l ong ) began e n t e r i n g t h e e s t u a r y i n January and peaked i n abun- dance i n February and March; most s tayed i n t h e upper e s t u a r y ' s f r e s h - water channels ( t h e D e l t a ) . A l a t e r em ig ra t i on of ch inook smo l ts (80-90 mm long) occur red from A p r i 1 t o June; t h e

f i s h moved q u i c k l y through the D e l t a and Suisun and San Pablo Bays. Chinook salmon srnol t s t y p i c a l l y use es tua r i es o n l y as m ig ra t i ona l c o r r i d o r s t o t h e ocean (Reimers 1973; K je lson e t a l . 1982; Simenstad 1983), whereas f r y remain i n t he es tuary u n t i 1 they become l a r g e r and envi ron- mental cond i t i ons s t imu la te them t o move i n t o t h e ocean.

Est imates o f chinook f r y r e s i - dence t ime i n nor thwestern U.S. and Canadian es tua r i es ranged f rom 10 days t o 2 months (Shepard 1981). Probable f a c t o r s t h a t a f fec ted t h e i r l e n g t h o f s tay i n es tua r i es were f i s h size, popu la t ion dens i ty , prey abundance, h a b i t a t s u i t a b i l i t y , f reshwater i n f l o w ( p a r t i c u l a r l y abrupt increases) , and water temperature (Reimers 1973; Shepard 1981; K je l son e t a l . 1982; Simenstad 1983).

Chinook salmon f r y (30-50 rnm l ong) i n es tua r i es c h a r a c t e r i s t i c a l l y feed i n schools i n l i t t o r a l o r shal low sub1 i t t o r a l h a b i t a t s such as s a l t - marshes, mudf l a t s , and o the r i n t e r - t i d a l areas. The feed ing hab i t s o f chinook salmon f r y are regu la ted l a r g e l y by t he t i d a l cyc le. For exam- p le , du r i ng f l o o d t i d e , f r y move f rom smal l t i d a l channels i n t o near-shore marshes (Healey 1980, 1982). Noctur- na l onshore movements f o r feed ing have a l so been described f o r chinook salmon f r y (Myers 1980; Cannon 1982). Larger f r y and smolts congregate i n sur face waters o f main and subs id ia ry channels and move i n t o shal low s u b l i t t o r a l zones t o feed. Occasional l y they en ter b l i n d t i d a l channels, but t h e i r s tay appears t o be t r a n s i t o r y (Shepard 1981; Simenstad 1983). The composi- t i o n o f t he subs t ra te i n es tua r i es inhab i ted by salmon i s commonly mud, s i l t , and sand, and l e s s f r equen t l y , coarser r ~ ~ a t e r i a l s (Forsberg e t a1 . 1977; Healey 1980).

The d i s t r i b u t i o n o f chinook salmon f r y i n t h e Sacramento-San Joaquin Estuary seemed t o be regu la ted by f reshwater i n f l ow dur ing the

downstream m ig ra t i on (K je lson and Raquel 1981). I n years o f h igh f reshwater in f low, t he f r y inhab i ted both upper freshwater channels ( t he De l ta ) and the brack ish waters o f Suisun Bay and San Pablo Bay. I n years of low flow, most of the f r y were r e s t r i c t e d t o t he upper De l ta . Spr ing discharge a l so a f f e c t s s u r v i v a l o f f r y i n es tua r i es . High f reshwater i n f l ow may reduce the m o r t a l i t y o f chinook salmon f r y and smolts caused *

by h igh water temperatures, water d i ve rs ion , and predat ion.

Sand s i l l s f r equen t l y form a t the mouths of small coasta l streams i n no r the rn C a l i f o r n i a ; these cause lower t i d a l movement and s a l i n i t i e s than those found i n l a r g e r open es tuar ies . I n such a stream, f u r t h e r emigra t ion i s prevented by t h e s i l l and t h e growth and m o r t a l i t y o f j u v e n i l e s a re a f f e c t e d by t h e s i z e o f the es tua ry and t h e popu la t i on dens i t y o f chinook and t h e i r p redators (Reimers 1973). A s t rong re1 a t i o n between ch i nook salmon abundance and avai l a b i 1 i t y o f s u i t a b l e h a b i t a t suggests t h a t es tuar ine land " rec lamat ion" may s u b s t a n t i a l l y reduce t h e b i o l o g i c a l c a r r y i n g capac i ty of t he es tuary (Levy and Northcote 1982). Also, land management p rac t i ces ( levees, stream channel i ng and breaking sand s i 11 s) t h a t reduce es tuar ine t rapp ing o f incoming a1 lochthonous ma te r i a l s may reduce t h e d e t r i tus-based food web be l ieved t o be necessary t o ma in ta in an abundance o f j u v e n i l e salmon ( S i b e r t e t a l . 1978; Healey 1982).

Oceanic _Residence

Upon en te r i ng t h e ocean, most o f t he chinook salmon smolts from the Sacramento-San Joaquin Estuary migrate northward, bu t a sp r i ng f i s h e r y f o r chinook salmon south o f San Francisco Bay a t Monterey i s evidence t h a t t he re i s some southward m ig ra t i on (Snyder 1931 1. The ex ten t o f northward movement f l u c t u a t e s considerably, depending on ocean e n v i r o n m q t a l cond i t ions , food a v a i l a b i l i t y , and

race. For example, i n a mark and recovery study, over 50% o f t h e 1949 yea r - c l ass of f a 1 1 - run chinook salmon from t h e Sacramento R ive r were caught n o r t h o f t h e Oregon border , b u t i n a f o l l ow ing s t udy 90% were caught south of t h e r e (Jensen 1971). Analyses o f P a c i f i c coas t ca t ch da ta ( s p o r t and commercial) suggest t h a t f a l l - r u n ch inook salmon spend most, i f n o t a l l , o f t h e i r oceanic l i f e near shore, r e l a t i v e l y c l o s e t o t h e i r home r i v e r . Sp r i ng - run ch inook salmon o f t e n l eave nearshore waters i n t h e i r f i r s t year o f l i f e and seek o u t more n o r t h e r l y h i gh seas areas ( H a r t t 1980; ~ e a l e y 1983 1.

Male and female chinook salmon u s u a l l y spawn when t hey a re 3 t o 4 years 01 d . Two-year-01 d ma1 e spawners (commonly c a l l e d " j a c k s " ) usual l y make up 10% t o 25% o f t h e spawning r u n i n C a l i f o r n i a waters . Yea r l i ng male chinook salmon may mature be fo re t hey emig ra te t o t h e ocean ( R u t t e r 1904; Rich 1920).

Fac to r s t h a t account f o r t h e r e t u r n o f a d u l t salmonids t o t h e i r n a t a l streams are among t h e most p e r p l e x i n g and l e a s t understood f ace t s of salmon b i o l o g y . The consensus o f salmon b i o l o g i s t s i s t h a t h i gh seas n a v i g a t i o n i s i n n a t e l y c o n t r o l led, and t h a t t h e r o l e o f e x t r i n s i c env i ron- mental f a c t o r s inc reases i n importance as t h e salmon approach t h e i r home es tua r y (Brannon 1981 1. O r i e n t a t i o n i n mar ine waters i s be l i e ved t o i n v o l v e magnet ic and c e l e s t i a l i n f o r - mat ion, i n t e r p r e t e d by t h e i n n a t e l a t i t u d i n a l and ca lendar senses o f t h e f i s h e s (Brannon 1981; Qu inn 1981 1. The l e n g t h of day, r a t e o f change o f day leng th , sun p o s i t i o n , and l i g h t p o l a r i z a t i o n are suggested cues. Nearshore m i g r a t i o n may be enhanced by onshore winds t h a t concen t ra te r i v e r water c l o s e t o shore where o l f a c t o r y cues f u r t h e r gu ide t h e salmon (Bankc 1969 1.

GROWTH

Chinook salmon f r y newly emerged f rom t h e redd a re 35 t o 44 mm l ong and weigh as much as 0 . 5 g (R ich 1920). F r y grew 0.26 t o 0.40 mmlday (mean 0.33 mnlday) i n t h e upper Sacramento R i ve r , b u t d u r i n g t h e same pe r i od , 0.40 t o 0 .69 mm/day (mean = 0.53 mm/day) i n t h e es tua r y ( K j e l s o n e t a l . 1982). Growth r a t e s g e n e r a l l y inc rease i n e s t u a r i e s (R ich 1920; Reimers 1973). I n more n o r t h e r n e s t u a r i e s , g rowth ranged f rom 0.37 t o 1.32 mm/day (Shepard 1981). The r a t e o f growth o f ch inook salmon f u r t h e r acce le ra tes when t hey e n t e r t h e ocean. Fa1 1 - run ch inook salmon smol t s average 8 cm t o t a l l e n g t h (TL) when t hey leave t h e Sacramento-San Joaquin Es tuary and a r e as l o n g as 30 cm by t h e end o f t h e i r f i r s t yea r (Jensen 1971). The average l eng ths o f ch inook salmon o f d i f f e r e n t aqes a r e shown i n Table 1.

The averaae weights o f salmon a re g rea tes t j u s t before t hey m ig ra te i n t o t h e r i v e r t o spawn. They l o s e 15% t o 20% o f t h e i r body we igh t d u r i n g upstream m i g r a t i o n i n l a r g e r i v e r systems and an a d d i t i o n a l 10% t o 15% d u r i n g spawning ( R u t t e r 1904).

Table 1. Mean t o t a l l eng th (cm) and ( i n parentheses percen t compos i t i on a t each age of fa1 1 - run chinook salmon i n t h e C a l i f o r n i a commercial t r o l l f i s h e r y , 1970-72 ( f r om Denega 1973).

Age i n yearsa Year 1 2 3 4 5

1970 34.0 45.7 68.6 83.8 (32) (50) (17)

1971 32.3 48.3 68.6 83.8 ( 11 ) (60) ( 28 )

1972 - 43.2 68.6 81.3 ( 21 ) ( 46 ) (32)

a ~ e n g t h s a t age 1 were de r i ved back c a l c u l a t i o n o f sca le .

99.9 ( 1 ) 99.1 ( 1 96.5 ( 1 )

f rom

THE FISHERY

The Cal i f o r n i a commerci a1 salmon f i s h e r y began a1 ong t h e Sacramento R i v e r i n t h e m id -1800 ' s . By 1881, 20 c a n n e r i e s were p r o c e s s i n g ove r 10 m i l l i o n pounds o f ch inook salmon f r o m t h e Sacramento and San J o a q u i n R i v e r s . Two y e a r s l a t e r t h e f i s h e r y c o l l a p s e d , presumably as a r e s u l t o f o v e r - f i s h i n g and t h e l o s s o f spawning h a b i t a t from g o l d m i n i n g o p e r a t i o n s ( F r e y 1971; Jensen 1971 ). G i l l n e t s , were t h e most e f f i c i e n t means o f c a t c h i n g salmon i n t h e r i v e r s , b u t as c a t c h e s d e c l i n e d i n t h e l a t e 1 8 0 0 ' s , some f i s h e r m e n began t r o l l i n g i n o f f - sho re wa te rs . The Cal i f o r n i a ocean t r o l l f i s h e r y began near Monterey i n t h e 1 8 8 0 ' s and near Eureka and Crescent C i t y i n 1916 ( F r e y 1971) . Chinook salmon caugh t i n t h e ocean c o n s t i t u t e d an i n c r e a s i n g p r o p o r t i o n o f t h e commerc ia l salmon c a t c h because t h e m a j o r n o r t h e r n Cal i f o r n i a r i v e r s were c l o s e d t o commerc ia l salmon f i s h i n g f r o m 1919 t o 1933. The commercial salmon f i s h e r i e s i n t h e Sacramento and San J o a q u i n R i v e r s c l o s e d i n 1957. Annual c h i n o o k salmon c a t c h e s i n C a l i f o r n i a were h i g h e s t i n 1918-19 and 1945-46 ( o v e r 1 3 m i l l i o n pounds each y e a r ) ; r e c o r d l ow l a n d i n g s o f l e s s t h a n 4 m i l l i o n pounds were r e p o r t e d f o r 1938-39, 1941, 1958 and 1983. A summary o f t h e annual C a l i f o r n i a ocean s p o r t and commerc ia l t r o l l c a t c h e s f o r s e l e c t e d y e a r s f rom 1940 t o 1983 i s shown i n T a b l e 2.

A l l o f t h e commercial salmon now landed i n C a l i f o r n i a wa te rs a r e caught by ocean t r o l l i n g . Annual l y , an average o f 4,800 salmon t r o l l i n g boa ts expended 75,000 f i s h i n g days f r o m 1978 t o 1983 (PFMC 1984) . S p o r t - f i s h i r g i n t h e ocean has f l o u r i s h e d s i n c e Wor ld War I 1 and now c o n t r i b u t e s abou t 21% o f t h e C a l i f o r n i a c a t c h . The ocean s p o r t f i s h e r y i n C a l i f o r n i a suppor ted an average o f 193,000 a n g l e r t r i p s a n n u a l l y between 1971 and 1983 (PFMC 1984 1.

Tab le 2. The number o f ch inook salmon i n t h e s p o r t f i s h e r y and t h e w e i g h t and v a l u e ( a l l i n thousands) o f ch inook salmon i n t h e commercial f i s h e r i e s o f C a l i f o r n i a , 1940-83 ( d a t a f r o m N a t i o n a l M a r i n e F i s h e r i e s S e r v i c e 1940-75 and P a c i f i c F i s h e r y Management C o u n c i l 1984).

S p o r t f i s h e r y Commercial Year Numbers Pounds Do1 1 a r s

a ~ a y i n c l u d e some coho salmon.

The Sacramento R i v e r and s e v e r a l o t h e r n o r t h e r n c o a s t a l r i v e r s i n C a l i f o r n i a s u p p o r t a s u b s t a n t i a l s p o r t f i s h e r y f o r ch inook salmon. From 1977 t o 1981, t h e average s p o r t c a t c h o f f a 1 1 - run ch inook salmon i n t h e Sacramento R i v e r was 1.8% o f t h e t o t a l e s t i m a t e d r u n (Hoopaugh and Knu tson 1979; Knutson 1980; Reav is 1981a, 1981b, 1983) . The s p o r t c a t c h o f t h e r e m a i n i n g t h r e e s t o c k s averaged 1.8% o f t h e l a t e f a l l r u n , 1.7% of t h e w i n t e r r u n , and 2.5% o f t h e s p r i n g run . The salmon s p o r t f i s h e r y i n t h e K lamath R i v e r i s e s t i m a t e d t o compose up t o 13% o f t h e t o t a l ch inook salmon r u n and 7% o f t h e t o t a l ocean s p o r t and commercial c a t c h e s o f K lamath R i v e r f i s h (U.S. F i s h and W i l d l i f e S e r v i c e 1980, 1981, 1982, 1983, 1984).

The economic v a l u e o f t h e P a c i f i c c o a s t salmon f i s h e r y i s o f g r e a t impor tance , r a n k i n g second i n q u a n t i t y and v a l u e i n t h e e n t i r e 1983

U.S. mar ine ca t ch (NMFS 1984). The es t imated va lue o f Cal i f o r n i a l s commercial chinook salmon f i s h e r y i s shown i n Table 2. The d o l l a r va lue o f commercial salmon depends on f i s h s i z e and docks ide ex-vessel p r i c e (Wahle e t a l . 1974). I n 1983, ex-vessel p r i c e s p e r pound ranged f rom $1.40 f o r smal l salmon l e s s than 8 1b t o $2.25 f o r f i s h l a r g e r than 12 l b (PFMC 1984). The exac t va lue o f t h e ocean s p o r t salmon f i s h e r y i s d i f f i c u l t t o ascer ta in , b u t an es t ima te o f t h e n e t economic s p o r t va lue o f a chinook salmon i s $63.00 per f i s h . Chinook salmon caught i n r i v e r s a re es t imated t o be wor th $28.00 pe r f i s h (Mathews and Brown 1970).

According t o Wr ight (1981), t h e salmon f i s h e r y needs t o be regu la ted f o r optimum y i e l d . He suggested t h a t optimum y i e l d may be reached by us i ng area and season c losures , minimum s i z e l i m i t s , and gear r e s t r i c t i o n s . A more d i r e c t method would be through t he es tab l i shment o f l i m i t e d e n t r y o r ca t ch quotas. Catch quotas have been i n s t i t u t e d i n Oregon and Washington, and r e c e n t l y t h e Cal i f o r n i a l e g i s l a - t u r e has j o i n e d Oregon and Washington i n an a t t emp t t o l i m i t t h e e n t r y o f new f i s h i n g boa ts i n t o t h e e x i s t i n g f 1 e e t (PFMC 1984).

The magnitude o f t h e chinook salmon f i s h e r y has p robab ly c o n t r i b u t e d t o t he d e c l i n e i n abundance o f t h e species. R icker (1980, 1981 a t t r i b u t e d t h e apparent decrease i n s i z e and ,age a t m a t u r i t y o f chinook salmon s tocks t o t h e huge salmon ca t ch i n t h e commercial t r o l l f i s h e r y a long t he P a c i f i c coast. S ince t h e 19201s, t h e average weight o f t r o l l - c a u g h t chinook has decreased s i g n i f i c a n t l y (some 2.5 kg i n B r i t i s h Columbia waters f rom 1951 t o 1975), and mean age a t m a t u r i t y f o r r e t u r n i n g a d u l t s has decreased f rom 4 years t o 3 years. R i cke r (1980) s t a t e d t h a t t rends i n ocean temperatures a re no t known t o be respons ib l e f o r t he age and s i ze decreases, bu t o f f e r s severa l o the r p o s s i b l e exp lana t ions :

1. The increased i n t e n s i t y o f t he t r o l l f i s h e r y has r e s u l t e d i n more salmon be ing caught e a r l y i n t he season and a t a sma l le r s i ze .

2. The ocean ca tch has been so l a r g e t h a t fewer salmon su rv i ve t o o l d e r ages and young f i s h make up a bu lk o f t he ca tch ( i .e. , t h e " f i s h i n g - u p e f f e c t " ) .

3. The excess ive removal o f l a t e - ma tu r i ng salmon f avo rs reproduc- t i o n o f smal l e r , ea r l y -ma tu r i ng f i s h .

The increased p r o p o r t i o n of younger f i s h i n t he spawning p o p u l a t i o n had been recognized e a r l i e r by Warner e t a1 . (1961) f o r t h e Sacramento R iver and by Junge and Phinney (1963) f o r t he Columbia R i ve r .

Current C a l i f o r n i a s tocks o f c h i nook salmon are h e a v i l y supplemented by ha tchery f i s h t h a t are re leased as f r y o r f i n g e r l i n g s ( l a r g e f r y t o y e a r l i n g s ) . Now be ing eva lu - a ted a r e t h e s u r v i v a l o f hatchery- r ea red salmon and t h e i r c o n t r i b u t i o n t o t h e of fshore f i s h e r y , r e t u r n s t o t h e ha tchery i n r e l a t i o n t o f i s h s i z e a t t h e t i m e o f r e l ease and t h e d i s t ance f rom t h e p o i n t o f r e l ease t o t h e ocean (Sholes and H a l l o c k 1979; K j e l s o n e t a l . 1982). P roduc t i on o f ch inook salmon (S ta te and Federa l ha t che r i es ) i n C a l i f o r n i a f rom 1971 t o 1981 i s shown i n Table 3.

ECOLOGICAL ROLE

Compet i t ion

Compet i t ion f o r spawning g rave l s between chinook salmon and o the r anadromous species i s l i m i t e d because o f t he chinook salmon1 s p re fe rence f o r spawning grounds i n mainstem o r l a r g e t r i b u t a r y streams and t h e i r e a r l y p e r i o d o f upstream m i g r a t i o n and spawning . Downstream d isperson o f newly emerged salmonid f r y i s a d e n s i t y adjustment mechanism and may

ÿ able 3. The numbers (thousands) and weight (thousands o f pounds) o f j u v e n i l e fa1 l - r u n chinook salmon ra i sed i n S ta te and Federal ha tcher ies and re leased i n C a l i f o r n i a r i v e r s from 1971 t o 1981 (data from C a l i f o r n i a Department of F i s h and Game 1972-84 and U.S. F i sh and W i l d l i f e Serv ice 1970-81).

S ta te Federal Year Number Weight Number Weiglht

1971 37,845 413 8,186 118 1972 28,793 446 12,360 115 1973 23,384 452 10,971 114 1974 15,115 371 12,518 113 1975 27,039 443 7,205 27 1976 24,947 456 8,544 104 1977 24,723 535 10,129 116 1978 14,598 335 8,719, 84 1979 16,187 555 7,411 1 1 7 ~ 1980 20,133 677 16,951 229 1981 34,850 650 16,060 138

a ~ n c l udes some wi n te r - run c h i nook salmon.

r e s u l t i n cohab i t a t i on o f chinook salmon f r y w i t h j u v e n i l e steelhead t r o u t or coho salmon (Reimers 1973 1. Juven i le chinook salmon, 1 i ke o ther stream-dwell i n g salmonids. arg. t e r r i t o r i a l , and competi t i o n f o r food and space may r e s u l t when they l i v e i n t he same waters w i t h o ther salmonids. F r y o f chinook salmon and coho salmon se lec t s i m i l a r h a b i t a t , and coho salmon are t h e more aggressive o f t he two species ( L i s t e r and Genoe 1970; S te in e t a1 . 1972). The aggression and t e r r i t o r i a l i t y o f salmon f r y appear t o be i n f l uenced by c u r r e n t v e l o c i t y , and a re subdued i n l a r g e pool s and es tua r i es where school i ng i s common (Reimers 1968). I n t r a - s p e c i f i c dominance i s 1 a rge l y governed by f i s h s i z e (Chapman 1962; Reimers 1968).

The e a r l y downstream m ig ra t i on o f ocean-type c h i nook salmon f r y

reduces contac t w i t h o ther species, but l a rge i n t roduc t i ons o f hatchery- reared coho salmon may encourage premature emigra t ion o f c h i nook salmon f r y from f reshwater i n t o es tua r i ne o r oceanic waters and cou ld reduce growth and s u r v i v a l o f t he chinook salmon migrants ( S t e i n e t a l . 1972). Myers (1980) repor ted a l a rge degree o f feed ing over lap i n es tua r i es between w i l d chinook j uven i l es and hatchery- re leased coho salmon and hypothesized a h igh p o t e n t i a l f o r compet i t ion. Stream-type chinook salmon l i v e i n f reshwater f o r up t o a year and f r e q u e n t l y occur w i t h j u v e n i l e steelhead t r o u t . The s e l e c t i o n o f d i f f e r e n t h a b i t a t s by t h e two species reduces compet i t ion f o r space o r food (Everest and Chapman 1972).

Upon e n t e r i n g t h e estuary, chinook salmon f r y and smolts a re conf ron ted w i t h a s i z a b l e assemblage o f p o t e n t i a l competi t o r s . High popu la t i on d e n s i t i e s o f chinook salmon w i t h i n es tuar ies increase i n t r a - s p e c i f i c compet i t ion and may r e s u l t i n reduced summer growth and e a r l y ocean e n t r y (Reimers 1973). Shepherd (1981) repor ted t h a t f i shes i n es tua r i es known t o e a t t he same food as t h a t p re fe r red by chinook salmon are coho salmon, chum salmon (0. m), p ink salmon (g. orbuscha ) s tee1 head t r o u t , c u t t h r 0 a ~ ~ ~ 1 mo c l a r k l ) , Do1 l y Varden (Sal v i 1 l nus ma1 ma), th reesp ine s t i ck leback (Gasterosteus aculeatus) , sh iner perch ( C mato a s t e r

s t a r r y f lounder * P l a t i c h - p r i c k l y m n

f i c staghorn scu l - p i n t o c o t t u s armatus), and P a c i f i c h e r r i n g +-- Clupea harengus). Other p o t e n t i a1 compet i tors i n t he Sacramen- to-San Joaquin De l ta a re j u v e n i l e Sacramento squawfish ( P t chochei lus g r a n d i s ) and De l ta s m e k $ i ~ ~ ~ ~ t r a n s p a c i f i c u s ) ( S c h a f f t e r 19-

The grea tes t competi t o r s o f chinook salmon i n the ocean are probably o ther P a c i f i c salmon, p a r t i c u l a r l y d u r i ng peak abundance i n nearshore waters. Evidence o f mari ne

densi ty-dependent s u r v i v a l was noted by Peterman (1978) f o r no r t he rn P a c i f i c salmon stocks, bu t t he ocean proper p robab ly does not s e r i o u s l y l i m i t salmon p roduc t i on (Wal t e r s e t a1 . 1978). Ana lys is of food resources of t h e no r t he rn P a c i f i c Ocean suggests t h a t t he supply o f food f o r salmon i s n o n l i m i t i n g (Ro thsch i l d 1972).

Preda t ion

Preda t ion on salmon eggs u s u a l l y i s no t a major cause o f m o r t a l i t y because t h e eggs a re i n t he subs t ra te . Preda t ion on chinook salmon f r y may be h igh when they beg in t h e i r downstream m ig ra t i on . When salmon are concen- t r a t e d above o r below dams o r water d i v e r s i o n s t r u c t u r e s , some are easy p rey t o p i sc i vo rous b i r d s such as be1 t e d k i n g f i s h e r s (Cery le a1 cyon), herons (Ardeidae) , and mergansers (Mergus spp. ) , and l a r g e r salmonids, scu lp i ns , Sacramento squawfish, and s t r i p e d bass (Morone s a x a t i l i s ) . Hatchery-re leased f i n g e r l i n g ch inook salmon and s tee lhead t r o u t i n Sacramento R i v e r t r i b u t a r i e s p r e y h e a v i l y on t h e sma l l e r w i l d ch inook salmon f ry (Sholes and Hal l o c k 1979; Menchen 1981).

Preda t ion by l a r g e r salmonids on chinook salmon f r y and smol ts may be s u b s t a n t i a l i n es tua r i es . Coho salmon smolts a re known t o be h i g h l y p i sc i vo rous d u r i n g ou tm ig ra t i on (Parker 19681, and p reda t i on by coho salmon and o ther p reda to rs may s i g n i f i c a n t l y reduce s u r v i v a l o f hatchery-re leased salmon f r y o r smol t s (Peterman and Gat to 1978). Other es tua r i ne p reda to rs i n c l ude mergan- sers, cormorants (Phal acrocorax spp. 1, grebes (Podic ipedidae) , loons (Gavia SPP. ), and ospreys (Pandion ha1 i ae tus ) .

The ex ten t o f h i gh seas p reda t i on i s unknown, b u t l oss o f salmon t o no r t he rn f u r seals ( ~ a l l o r h i n ~ s spp.) may range from 2 m i l l i o n t o 60 m i l l i o n salmon annua l l y (Peterman 1978). The salmon shark

(Lamna d i t r o p i s ) i s another h i gh-seas p reda to r . Nearshore p reda to rs a re cormorants, ospreys, sea 1 ions (Eumetopias juba tus and Zal ophus c a l i f o r n i a n u s b , harbor sea ls (Phoca v i t u l i na), b l u e sharks (Pr ionace j laucaa) , and lampreys (Lampetra spp. 1.

Chinook salmon tend t o be more o p p o r t u n i s t i c feeders than o the r salmonids (Healey 1982). F r y i n streams feed e x t e n s i v e l y on d r i f t i n sec t s (Ru t t e r 1904 1, bu t zooplankton a r e more h e a v i l y eaten i n main r i v e r systems and es tua r i es . Adu l t and j u v e n i l e d i p t e r a n i nsec t s and crustacean zooplankters -- e s p e c i a l l y Cladocera and Copepoda -- are p r i n c i - pa l food i tems o f chinook f r y i n t h e Sacramento R iver and t he Sacramento- San Joaquin Es tuary (F i gu re 5 ) . Smolts feed on gammarid amphi pods and l a r v a l f i s h i n b rack i sh waters; l a r g e r and o l d e r smol ts s e l e c t l a r g e r crustaceans (Corophi um and Neomysis and f i s h as food (Cannon 1982). The s h i f t from sha l low ep iben th i c p rey t o l a r g e r , o f t en pe lag i c species r e f l e c t s the movement of j u v e n i l e s f rom sha l low l i t t o r a l h a b i t a t s i n t o deeper r i v e r and t i d a l channels as they inc rease i n s i ze . Food consumed by marine d w e l l i n g j u v e n i l e s c o n s i s t s p r i m a r i l y o f f i s h , crustaceans, and i nsec t s (Snyder 1924 1. Marine p rey o f a d u l t chinook salmon are pe lag i c crustaceans such as k r i l l (euphaus i ids ) , l a r v a l crabs, and f i s h (F i gu re 5 ) .

ENVIRONMENTAL REQUIREMENTS

Temper a m

Chi nook salmon are co1 dwater f i s h b u t they a re more t o l e r a n t of h igher water temperatures than o the r P a c i f i c salmon ( B r e t t 1952). Optimum, t o l e r a b l e , and l e t h a l water tempera- t u r e s f o r d i f f e r e n t l i f e stages of chinook salmon a re g i ven i n Table 4 . Excess ive ly abrup t water temperature changes may k i l l f i s h even w i t h i n

American R. n=245(25-104mm) %Number (Barnhart and Giebink 1983)

Sacramento-San Joa uln Delta n.540 (170mm) 8 ~ u m b e r

(Kjelso~et a1 1982)

CA Coast n= 1004 (3 3 1041mm) O h Volume (Merkel 97- 1957

t o l e r a t e d ranges. I n t h e De l ta , water temperatures t h a t exceed 23 C are l e t h a l t o most chinook smolts (K je l son e t a1 . 1982 1.

S a l i n i t y

Among t h e P a c i f i c salmons, juve- n i l e chinook salmon are most t o l e r a n t o f changing s a l i n i t i e s . S h o r t l y a f t e r hatching, t h e a lev ins t o l e r a t e moder- a te s a l i n i t i e s (15 pp t ) , and a t 100 davs o f aqe and a t a mean l eng th o f 65 mm, they t o l e r a t e f u l l - s t r e n g t h seawater (Wagner e t a1 . 1969 1. Sal i - n i t y t o l e rance can be broadened by acc l ima t i on and i s increased by t h e s i z e o f t h e f i s h and r a t e o f growth. Despi te a h igh t o l e rance f o r h igh s a l i n i t i e s , s tud ies i n t h e Sacramento- San Joaquin Estuary and i n southern Canadian es tua r i es suggested an appar- en t preference o f low sa l i n i t y water by chinook salmon f r y (Healey 1982; K je l son e t a1 . 1982). The s a l i n i t y requirements o f j u v e n i l e chinook s a l - mon are l i s t e d i n Table 4. Adu l t salmon t o l e r a t e r a p i d s a l i n i t y changes.

Dissolved Oxytien

F igu re 5. Stomach con ten ts o f

The d isso lved oxygen (DO) requirements o f chinook salmon embryos are unclear , bu t A lderd ice e t a l . (1958) observed an increase i n oxygen demand by chum salmon embryos as they neared hatching. The e f f e c t s o f DO concent ra t ions below t h e s a t u r a t i o n l e v e l on salmonids i nc l ude delayed o r premature ha tch ing (depending on t h e t i m i n g o f low DO i n t he egg devel~opment process) ; abnormal embryo development; reduced s i z e and s t reng th a t hatching; reduced growth, feeding, and swimming ab i 1 i ty; and increased s u s c e p t a b i l i t y t o disease, predat ion, and t o x i c contaminants (Ors i 1967;

chinook salmon o f d i f f e r e n t Davis 1975). The DO requirements o f l eng ths ( i n parentheses) and chinook salmon may change a t var ious hab i t a t s . l i f e stages (Table 4).

Table 4. Temperature, sa l i n i t y , and d i sso l ved oxygen requirements f o r several l i f e stages o f ch inook salmon.

Environmental L i m i t s f a c t o r L i f e stage Optimal Tolerance Le tha l Comments

Tgmperature Adu 1 t ( C) upstream

m i g r a t i o n

Sal i n i t y ( P P ~ )

Spawn i ng

Egg incubat i o n

Juven i le 12-13~ r e a r i n g

Juven i 1 e r e a r i n g

10.6-19.4: Fa1 1 - run chinook 3.3-13.3 Spring-run chinook

5.8-14.2' < 0.6' Eggs su rv i ve near f r eez ing a f t e r i n i t i a l develop- ment t o 128 c % l l stage a t 5OC.

< 0.8; Accl imated a t 1 0 : ~ >25.1 Accl imated a t 24 C

A t 10 days pos t - hatch

>30f A t yolk-sac ab- s o r p t i o n ( w i t h accl ima t i on ) or a t 100 days post hatch (w i thout acc l ima t i on )

Dissolved Adu 1 t >5.0 b

oxygen upstream (mg/ l ) m i g r a t i o n

E gg Sa tu ra t i on incubat i o n

Juveni 1 e rea r i ng

< 1 . 6 ~ As percent sa tu r - a t i o n decreases, growth decreases and abnormal i t ies and m o r t a l i t y increase.

>4.5 h Avoidance a t 16- 2 5 " ~ .

>3 .oh Avoidance a t 8- i aOc .

a ~ e l 1 (1973). b ~ e i s e r and B jornn (1979). 'combs and Burrows (1957). d l i p e r e t a l . (1982).

e ~ r e t t (1952). f ~ a g n e r e t a1 . ( i969) . g ~ i 1 ver e t a1 . (1963). h ~ h i t m o r e e t a1 . (1960).

Subs t ra te

Subs t ra te requi rements a re f a i r l y r i g i d f o r success fu l spawning and egg incubat ion . Chinook salmon spawn over a subs t ra te of unconsol i da ted ma te r i a1 s o f t h e app rop r i a te s i z e and adequate i n t r a g r a v e l water f low, w i t h proper stream depth, c u r r e n t v e l o c i t y , and bottom contour. The requi rements f o r spawning and r e a r i n g o f c h i nook salmon are descr ibed i n Table 5. Chinook salmon f r y tend t o p r e f e r s o f t subs t ra tes , p o s s i b l y because o f t h e p re fe r red low water v e l o c i t i e s there,

bu t f r y a l s o i n h a b i t areas o f gravel , cobble, o r bedrock i n e i t h e r streams or e s t u a r i e s (Everest and Chapman 1972; Healey 1980). Juveni l e spr ing- r u n salmon t h a t ove rw in te r i n streams are known t o seek coarse subs t ra tes (cobble o r bou lder ) f o r p r o t e c t i o n aga ins t heavy w i n t e r and s p r i n g f l ows (Chapman and B jo rnn 1969 1.

The g rea tes t t h r e a t t o t h e subs t ra te qua1 i t y i s t h e accumulat ion o f f i n e sediments on spawning g rave ls and food-producing areas (Cordone and K e l l e y 1961). Excess ive sed imenta t ion c logs g rave l i n t e r s t i c e s and reduces

Table 5. H a b i t a t requ i rements o f severa l 1 i f e s tages o f chinook salmon.

Environmental f a c t o r L i f e s tage

L i m i t s Optimal To1 erance Comments

Subs t ra te s i z e spawninga 1.3-10.2 (cm)

80% 1.3-5.1 cm, 20%>5.1 cm

Juven i 1 e s i l t r e a r i n g b

Depth (mlC Adu l t upstream m i g r a t i o n

Spawning

J u v e n i l e r e a r i n g

Water Adu l t upstream v e l o c i t y m i g r a t i o n (m/s 1

Juveni 1 F 0.06-0.24 r e a r i n g

s i l t - r u b b l e

< 2.4C - Susta ined c u r r e n t maximum

< 6.1 d - Obstac le c u r r e n t

maximum

90%-95% conf idence i n t e r v a l

a ~ e l 1 (1973). C~hompson (1972). b ~ v e r e s t and Chapman (1972). dneaver (1963).

16

i n t r a g r a v e l water f low, which i s e s s e n t i a l f o r t he t r a n s p o r t o f oxygen to , and me tabo l i c wastes from, incu- b a t i n g egg s u r f aces. Heavy sedimen- t a t i o n may a l s o t r a p a l e v i n s i n t h e gravel , caus ing s u f f o c a t i o n o r s t a r - va t i on . Sedimentat ion of r o c k y sub- s t r a t e s a l s o reduces t he avai l a b l e h a b i t a t f o r food organisms and reduces f i s h escape cover.

Minimum depths a re necessary t o assure successfu l upstream m i g r a t i o n of a d u l t salmon. Dur ing low f low, r i f f l e s may be t o o sha l low f o r a d u l t passage. Thompson (1972 1 developed methods by which c r i t i c a l areas a re i d e n t i f i e d and adequate passage f lows a re est imated. Depth i s impor tan t i n spawning s i t e s e l e c t i o n because i t a f fec ts t he h y d r a u l i c "head" and i n t r a g r a v e l f l ow. Chinook salmon a r e r e p o r t e d t o spawn a t depths up t o 10 m i n l a r g e r i v e r s (Chapman 1943), bu t g e n e r a l l y f a v o r depths l e s s than 3 m. Depth c r i t e r i a f o r m i g r a t i n g and spawning chinook are l i s t e d i n Table 5. Depth preference o f stream- dwe l l i n g j u v e n i l e chinook salmon i s about 1 m and may be i n f l uenced by water v e l o c i t y , ins t ream cover, f i s h s ize , and t h e abundance o f predat.ors and compet i tors . Chinook salmon f r y and smol ts i n e s t u a r i e s f a v o r su r f ace waters i n sha l l ow f l a t s o r deepwater channels.

Water Movement

Adequate c u r r e n t v e l o c i t i e s a re r e q u i r e d t o a s s i s t t h e female i n nes t excava t ion and f o r i n t r a - g r a v e l f l ow . Gangmark and Bakkala (1960) found s i g n i f i c a n t inc reases i n m o r t a l i t y o f chinook salmon eggs when i n t r a g r a v e l f l ow r a t e s dropped below 60 cm/h. Juven i l e chinook salmon i n streams and e s t u a r i e s .se lec t low v e l o c i t y h a b i t a t s , b u t i n streams t h e f ry wf 11 seek f a s t e r wa te rs as t hey grow l a r g e r and most s e l e c t l o c a t i o n s ad jacen t t o h i ghe r v e l o c i t i e s where p rey abundance

i s g rea te r (Everes t and Chapman 1972). Current v e l o c i t y preferences f o r spawners and j u v e n i l e s are g iven i n Table 5. The c r u i s i n g , susta ined, and d a r t i q g speeds of a d u l t chinook salmon are about 1.1, 3.3, and 6.8m/s, r e s p e c t i v e l y (Be1 1 1973). Maximum speeds depend on f i s h s ize, water temperature, d i sso l ved oxygen concen- t r a t i o n s , and s tage of m a t u r i t y .

The e s t i m a t i o n o f s t reamf low requi rements f o r j u v e n i l e salmonids i s ex t remely complex due t o t he i n t e r - a c t i o n of numerous phys i ca l , chemical , and b i o l o g i c a l f ac to r s . The Inst ream Flow Incrementa l Methodology ( IFIM) was developed by t he USFWS Cooperat ive Inst ream Flow Serv ice Group t o p r e d i c t the e f f e c t s o f a d e c l i n e i n f l o w and space on f reshwater f i s h popu la t i ons (Bovee 1982). Th i s procedure, a hydraul i c s i m u l a t i o n model t h a t i nco r - pora tes f i s h age and spec ies -spec i f i c h a b i t a t preference data, i s i n use throughout t he western Un i ted States. Flow requi rements f o r chinook salmon i n l a r g e r i v e r s are complex, b u t severa l s t u d i e s have assoc ia ted h i gh s u r v i v a l o f downstream migran ts w i t h h i gh d ischarges i n t h e s p r i n g (Wethera l l 1970; CDFG 1975; K je l son and Raquel 1981; K j e l s o n e t a l . 1982). Su rv i va l of chinook salmon smol t s i n t he Sacramento R iver was h i g h l y c o r r e l a t e d ( r = .94) w i t h f reshwater i n f l o w i n t he sp r i ng and es tua r i ne water temperatures ( K j e l s o n e t a l . 1982). Various da ta suppor t t he view t h a t years o f h i gh f reshwater i n f l o w i n t h e San Joaquin R iver r e s u l t i n g rea te r r e t u r n o f spawning a d u l t s 2.5 years l a t e r (CDFG 1975; K je l son and Raquel 1981).

T u r b i d i t y - Juven i l e salmonids a re capable

o f t o l e r a t i n g t u r b i d i t y as h i gh as 1,000 ppm, b u t r educ t i ons o f p r imary food p roduc t i on and f eed ing e f f i c i e n c y a re l i k e l y a t much lower t u r b i d i t i e s ( B e l l 1973). The migra- t i o n o f a d u l t salmon may be i n h i b i t e d a t t u r b i d i t i e s o f 4,000 ppm ( B e l l

1973), and chinook salmon a re repo r ted t o avoid t u r b i d waters i f given a choice (Cordone and Ke l l ey 1961). D i rec t harm t o f i s h by excessive suspended sediments i s probably r a r e i n nature and can be combatted i n p a r t by mucous secre t ions t h a t f l u s h g i 11 membranes. Abrasion and c logg ing of g i 11 lame1 l a e may r e s u l t under extreme t u r b i d i t i e s and are r e l a t e d t o the s i z e and hardness of the suspended ma te r i a l (Cordone and Kel l e y 1961 1. Prolonged exposure t o h i g h l y t u r b i d waters may cause th i cken ing o f g i l l lame1 lae , which reduces oxygen-carbon d iox ide exchange e f f i c i e n c y r e s u l t i n g i n an increase i n v u l n e r a b i l i t y t o disease (!el 1 1973). S i l t deposi ts are more damaging t o salmon than s i l t suspended i n the water column.

Heavy Metals

Acid-mi ne wastes from the Spr ing Creek drainage have caused numerous k i 11s o f chinook salmon, s tee l head

t r o u t , and other species i n the Sacramento River between Keswick Dam and Cottonwood Creek (a d is tance o f 33 r i v e r mi) (USFWS 1959; Prokopovich 1965; Nordstrom 1977). O f t he f o u r most abundant metals i n the mine waste, copper and z i n c are extremely t o x i c t o chinook salmon. Since 1963, the wastes have been c o l l e c t e d i n Spring Creek Reservoir and metered i n t o Keswick Reservoir a t l e v e l s thouqht t o be safe f o r anadromous f i s h (Fin layson and Ashuckian 1979). I n 1978, new i n t e r i m re lease schedules proposed by Wilson (1978) a l low f o r maximum d i s - solved copper and z inc concentrat ions of 5 pg/1 and 64 pg/ l , r espec t i ve l y (F in layson and Verrue 1980). Recently the water q u a l i t y program t o p a r t i a l l y con t ro l metal concentrat ions i n the Sacramento River (from acid-mine wastes from Spring Creek) has c u r t a i l e d the number of f i s h k i l l s (Wilson e t a l . 1981). The sub le tha l ef fects on chinook salmon and other f i s h species caused by chronic expo- sure t o the metals are not known.

LITERATURE

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Bams, R.A. 1969. Adaptat ions o f sockeye salmon associated w i t h i ncuba t i on i n stream grave ls . Pages 71-87 i n T.G. Nor thcote, ed. Symposi u r n on salmon and t r o u t i n streams. H.R. MacMil l a n Lectures i n F i she r i es , U n i v e r s i t y o f B r i t i s h Col umbia, Vancouver.

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salmo;~ (0. qo'rbuscha-1 . J. ~ i s h . Res. Board Can. 33 : 2716-2725.

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Be1 1, M.C. 1973. F i s h e r i e s handbook o f eng ineer ing requirements and b i o - l o g i c a l c r i t e r i a . U.S. Army Corps o f Engineers, Nor th P a c i f i c D i v i s i o n Contract No. DACW57-68-C-0086.

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Chapman, W.M. 1943. The spawning o f chinook salmon i n t he main Columbia River . Copeia 1943:168-170.

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Wr ight , S. 1981. Con temporary P a c i f i c salmon f i s h e r i e s management. N. Am. J. F i s h Manage. 1 ~ 2 9 - 4 0 .

Zaugg, W. S. 1981. Re1 a t i onsh ips between smol t i n d i c e s and m i g r a t i o n i n c o n t r o l l e d and n a t u r a l env i r on - ments. Pages 173-183 E.L. Brannon and E.O.Salo, eds. Salmon and t r o u t m i g r a t o r y behav io r sympo- sium. U n i v e r s i t y o f B r i t i s h Colum- b i a, Vancouver.

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PAGE : B i o l o g i c a l Report 82(11.49)*1 4. roll8 and Subldlm 5. O R o o r l ;*I.

Species P r o f i l e s : L i f e H i s t o r i e s and Environmental A p r i l 1986 Requirements o f Coastal Fishes and Inve r teb ra tes

C a l i f o r n i a Cooperative F ishery Research U n i t Humboldt S t a t e U n i v e r s i t y Arcata, CA 95521

12 Soonsony O~~anlaat len Name and A d d n l l (GI

Nat iona l Coastal Ecosystems Team U.S. Army Corps o f Engineers F ish and W i l d l i f e Serv ice Waterways Experiment S t a t i o n U.S. Department o f t h e I n t e r i o r P.O. Box 631 Washington, DC 20240 Vicksburg, MS 39180

*U.S. Army Corps o f Engineers Report No. TR EL-82-4 . I& A b a M N m r t 200 -ma)

Species p r o f i l e s are l i t e r a t u r e summaries o f t h e taxonomy, morphology, d i s t r i b u t i o n , abundance, 1 i f e h i s t o r y , and environmental requ i rements o f coasta l aqua t i c species. They a re prepared t o a s s i s t i n environmental impact assessment. The chinook salmon (Oncorhynchus tshawytscha) i s a va luab le s p o r t and commercial f i s h species and accounted f o r over 69% o f t he salmon caught o f f t he C a l i f o r n i a coast f rom 1971 through 1983. Chinook salmon spawning runs i n the Sacramento River , t h e major producer o f chinook salmon i n C a l i f o r n i a , a re d i v i d e d i n t o f a l l , l a t e f a l l , w in te r , and s p r i n g runs. 0kher. coasta l r i v e r s have f a l l and s p r i n g runs o f chinook o r o n l y a f a l l run. A f t e r hatching, t he sac - f r y l i v e i n the grave l f o r a month o r longer before they emerge as fry. Some f ry m ig ra te immediate1 y t o sa l twa te r , o the rs remain 2 t o 12 months i n f reshwater w o r e migra t ing . They remain i n the ocean from 1 t o 7 years; most females mature and r e t u r n t o f reshwater t o spawn a f t e r 2 t o 4 yea rs a t sea. Some males r e t u r n t o spawn a f t e r o n j y 1 year i n the ocean, bu t most r e t u r n a f t e r 2 t o 4 years. A l l chinook salmon d i e a f t e r they reen te r f reshwater, whether they spawn o r not.

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U.S.G.P.O. 1986/661-638

REGION 1 Regional Director U.S. Fish and Wildlife Service Lloyd Five Hundred Building, Suite 1692 500 N.E. Multnornah Street Portland, Oregon 97232

REGION 4 Regional Director U.S. Fish and Wildlife Service Richard B. Russell Building 75 Spring Street, S.W. Atlanta, Georgia 30303

REGION 2 REGION 3 Regional Director Regional Director U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service P.O. Box 1306 Federal Building, Fort Snelling Albuquerque, New Mexico 87 103 Twin Cities, Minnesota 55 1 1 1

REGION 5 REGION 6 Regional Director Regional Director U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service One Gateway Center P.O. Box 25486 Newton Corner, Massachusetts 02158 Denver Federal Center

Denver, Colorado 80225

REGION 7 Regional Director U.S. Fish and Wildlife Service 101 1 E. Tudor Road Anchorage, Alaska 99503

DEPARTMENT OF THE INTERIOR U.S. FISH A I D WILDLIFE SERVICE

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 theenvironmental and cultural values of our national parks and historical 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.