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[pq] US Army Corps of Engineers Portland District

5 >, Rogue Basin Dam t Fisheries Evaluation

Effects of Lost Creek Dam on the Distribution and Time of Chinook Salmon Spawning in the Rogue River Upstream of Gold Ray Dam

May 1991

: EFFECTS OF LOST CREEK DAM ON THE DISTRIBUTION AND TIME OF CHINOOK

SALMON SPAWNING I N THE ROGUE RIVER UPSTREAM OF GOLD RAY DAM

Rogue Basin F i she r ies Eva lua t ion P r o j e c t Research and Development Sect i on

Oregon Department o f F i s h and Wild1 i f e

2501 SW F i r s t S t r e e t P.O. Box 59 Port land, OR 97207

May 1990

The Un i ted S ta tes Army Corps o f Engineers funded t h i s p r o j e c t under c o n t r a c t OACW57-77-C-0033.

CONTENTS

Paqe

............................................................... FOREWORD ii

................................................................ SUMMARY 1

............................................. Spawnivg D i s t r i b u t i o n 1

Spawning Time ..................................................... 1

RECOMMENDATIONS ....................................................... 2

INTRODUCTION ........................................................... 3

METHODS ................................................................ 4

RESULTS ................................................................ 6

Spawning D i s t r i b u t i o n ............................................. 6

Spawning Time ..................................................... 10

DISCUSSION ............................................................. 17

ACKNOWLEDGEMENTS ....................................................... 20

REFERENCES ............................................................. 21

. APPENDIX A Tables o f Data R e l a t i n g t o Stud ies o f Chinook Salmon ...... 23

APPENDIX B . F igures Showing Annual Re1 a t i o n s h i p Between Loca t i on o f Carcass Recovery and Date o f Tagging ................................... 30

APPENDIX C . F igu res Showing Annual Re1 a t i o n s h i p Between Date o f Carcass Recovery and Date o f Tagging ................................... 34

APPENDIX D . R e l a t i o n between Gregor ian day. day -o f - yea r and week-of -year ........................................................... 38

FOREWORD

Th is r e p o r t i s based on 14 years o f research funded by t h e U.S. Army Corps o f Engineers. A s tudy o f t h i s d u r a t i o n has n e c e s s a r i l y i nvo l ved t h e c o l l e c t i v e e f f o r t o f many people s ince i t s i n c e p t i o n i n 1974. For t h i s reason, i t i s being presented as a s t a f f r e p o r t o f personnel on t h e Rogue Basin F i s h e r i e s Eva lua t i on P r o j e c t . The r e p o r t was d r a f t e d by Thomas S a t t e r t h w a i t e who was l a r g e l y respons ib le f o r t h e s tudy design and f o r t he analyses conta ined i n t h e r e p o r t . Barry McPherson superv ised t h e p r o j e c t and c r i t i c a l l y reviewed t h e analyses, concl usions, and recommendations i n t he f i n a l document.

Research on t h e d i s t r i b u t i o n and t ime o f chinook salmon spawning above Gold Ray Dam was i n response t o concerns by f i s h e r y managers on t h e increased r e t u r n o f f a l l chinook salmon t o spawning areas h i s t o r i c a l l y used by s p r i n g chinook salmon f o l l o w i n g t h e impoundment o f water by Los t Creek Dam. The research was p r i m a r i l y an outgrowth o f more i n t e n s i v e s tud ies o f ch inook salmon and s t e e l head popu la t ions t h a t began i n t h e Rogue R i v e r i n 1973. James L icha towich was respons ib le f o r t h e o r i g i n a l des ign and guidance o f research on anadromous salmonids a f f e c t e d by the ope ra t i on o f Los t Creek Dam. These d u t i e s were subsequent ly assumed by Steven Cramer who served as program leade r u n t i l 1985. T h e i r l eade rsh ip and i n s i g h t s on s tudy designs were l a r g e l y respons ib le f o r t h e 111 t i m a t e success o f research conducted by personnel i n t h e Rogue Basin F i she r i es Eva lua t i on P ro jec t .

The mainstem and t r i b u t a r i e s o f t h e Rogue R i v e r c o l l e c t i v e l y produce t h e l a r g e s t p o p u l a t i o n o f w i l d anadromous salmonids i n Oregon. The Rogue R i v e r suppor ts r e c r e a t i o n a l and commerci a1 f i s h e r i e s o f immense importance t o Oregon c i t i z e n s and i s n a t i o n a l l y renowned f o r i t s d i v e r s i t y and p r o d u c t i v i t y . A u t h o r i z i n g documents f o r Los t Creek Dam s t i p u l a t e t h a t f i s h e r i e s enhancement i s t o be an impor tan t b e n e f i t o f t h e dam, mai f i ly through improved temperature and f l ow . We hope our s tud ies w i l l ensure t h a t these bene f i t s a re achieved f o r present and f u t u r e genera t ions o f Oregon c i t i z e n s .

Alan McGie L i f e H i s t o r y S tud ies Program Leader Research and Devel opment Sec t ion Oregon Department o f F i s h and W i 1 d l i f e C o r v a l l i s , Oregon

14 March 1990

SUMMARY

In t h i s r e p o r t , we e v a l u a t e t h e e f f e c t of t h e o p e r a t i o n o f Lost Creek Dam on t h e spawning d i s t r i b u t i o n and t h e spawning time o f chinook salmon Oncorhynchus tshawytscha i n t h e Rogue River upstream of Gold Ray Dam. The Oregon Department of Fi sh and Wi l d l i f e conducted t h i s s tudy because managers became concerned about an i nc reased run of fa1 1 chinook salmon t o spawning a r e a s h i s t o r i c a l l y used by s p r i n g chinook salmon. Th i s change was no t ev iden t u n t i l j u v e n i l e s produced du r ing postimpoundment y e a r s matured and r e tu rned t o spawn ( S a t t e r t h w a i t e 1987). A summary o f our f i n d i n g s fo l l ows .

Spawning D i s t r i b u t i o n

1. Adul t s t h a t migrated e a r l i e s t spawned f a r t h e s t upstream.

2. Spawning of f a l l chinook salmon and sp r ing chinook salmon overlapped i n t h e a r e a between T r a i l Creek and t h e pool behind Gold Ray Dam. Few f a l l chinook salmon, bu t many s p r i n g chTnook salmon, spawned upstream o f T r a i l Creek.

3 . We d i d no t d e t e c t any change i n t h e spawning d i s t r i b u t i o n o f f a l l chinook salmon, pos s ib ly because we sampled few a d u l t s t h a t o r i g i n a t e d from preimpoundn~ent broods.

4 . Spring chinook salmon broods produced a f t e r f u l l ope ra t i on began a t Lost Creek Dam spawned f a r t h e r downstream compared with preimpoundment broods.

5. A dec rease i n t h e r e l a t i v e abundance of e a r l y mig ra t i ng a d u l t s , compared with 1 a t e migra t ing a d u l t s , was r e s p o n s i b l e f o r t h e downstream s h i f t i n t h e spawning d i s t r i b u t i o n o f s p r i n g chinook salmon.

6. Increased water t empera ture dur ing t h e per iod eggs and a1 ev i ns i ncubated i n t h e g r a v e l , o r i nc reased ha rves t r a t e w i th in t h e s p o r t f i s h e r y upstream of Gold Ray Dam, may have decreased t h e r e l a t i v e abundance o f e a r l y migran ts among wild s p r i n g chinook salmon t h a t r e t u r n e d t o t h e Rogue River.

Spawni ng Time

1. Adul t s t h a t mi g r a t e d e a r l i est spawned e a r l i es t . 2. Fa l l chinook salmon excavated few redds o f s p r i n g chinook salmon, bu t

probably i n t e r b r e d with t h e s p r i n g r ace . In t h e a r e a where spawning o f f a l l and s p r i n g r a c e s overlapped, spawning t ime d i f f e r e d 1 i t t l e between r a c e s .

3 . Spr ing chinook salmon broods produced a f t e r f u l l ope ra t i on began a t Lost Creek Dam spawned 1 a t e r tompared wS t h preimpoundment broods. Time o f spawning d i d not change among cohor t s o f ha tchery o r i g i n .

4 . The change t o l a t e r spawning was most pronounced f o r e a r l y migra t ing s p r i n g ch i nook salmon. Late migra t ing a d u l t s were 1 ess a f f e c t e d .

5. Spawning t ime c o r r e l a t e d w i t h water temperature when eggs and a l e v i n s incubated i n t h e grave l . Adu l ts spawned l a t e r when broods were exposed t o increased incuba t ion temperatures. Spawning t ime was n o t c o r r e l a t e d w i t h r i v e r phys i ca l parameters du r ing spawning.

6. La te r spawning of w41d sp r ing chinook salmon t h a t o r i g i n a t e d f rom pos t impoundment broods was probably t h e r e s u l t o f decreased s u r v i v a l r a t e among progeny o f e a r l y Spawnfng adul ts . Increased harves t r a t e w i t h i n t h e spo r t f i s h e r y upstream o f Gold Ray Dam may have a1 so decreased the re1 a t i v e abundance o f e a r l y spawning adu l ts .

RECOMMENDATIONS

1. The eva luat ion o f mod i f ied s t r a t e g i e s o f water temperature re leased from Lost Creek Dam should be completed. Decreased out f low temperature du r ing autumn may increase the abundance o f w51d sp r ing chinook salmon t h a t migra te (and spawn) e a r l y i n t h e season. Decreased o u t f l o w temperature may a1 so decrease t h e p ropor t i on o f fa1 1 chinook salmon among w i l d chinook salmon t h a t spawn upstream o f Gold Ray Dam.

2. Spawned carcasses should be surveyed annual ly i n t h e mainstem between Cole M, Rivers Hatchery and Shady Cove, and i n B i g Bu t te Creek, as p a r t o f a long- term management program f o r sp r ing chinook salmon i n t h e Rogue River basin. Any s i g n i f i c a n t changes i n spawning t ime should be f u r t h e r evaluated by rep1 i c a t f n g t h e study described i n t h f s r e p o r t .

Also, data from these surveys can be used t o es t imate t h e spawning escapement o f w i l d s p r i n g chinook salmon. The est imated r u n o f a d u l t s a t Gold Ray Dam i s n o t a re1 i a b l e est imate o f spawning escapement o f w i l d f i s h because (1) unmarked hatchery f i s h compose a l a r g e p o r t i o n o f t h e r u n and (2) harvest and prespawning m o r t a l i t y o f w i l d f i s h above Gold Ray Dam i s n o t accura te ly est imated.

3 . The m ig ra t i on t ime o f wSld and hatchery sp r ing chinook salmon should be est imated annual ly a t Gold Ray Dam as p a r t o f a long- term management program f o r spr ing chinook salmon i n t h e Rogue R i v e r basin. Est imates o f m ig ra t i on t i m i n g can be developed by scale ana lys i s 6 r by an expanded program o f marking j u v e n i l e s a t Cole M. R ivers Hatchery. Analys is o f scales would probably r e q u i r e extensive sampl i n g a t Gold Ray Dam, possl b l y as many as 200 adu l t s every 2 weeks.

A b e t t e r o p t i o n might be t o mark a constant proportion o f t h e re lease groups w i t h f i n c l i p s . Based on t h e f i n d i n g s o f Hankin (1982), we recommend a minimum mark r a t e of 25%. 'The markjng r a t e should be constant between years and between re lease groups. Also, t h e se lec ted mark should be v i s i b l e as adu l t s pass t h e count ing s t a t i o n a t Gold Ray Dam.

4 . E f f o r t s t o enhance t h e product ion o f sp r ing chinook salmon should concentrate on t h e r e s t o r a t i o n o f t h e e a r l y mfg ra t i ng component o f t h e w i l d stock. E a r l y migrants c o n t r i b u t e t o t h e r l v e r f i s h e r i e s a t a h ighe r r a t e than l a t e migrants. Wi ld f i s h a l so c o n t r i b u t e a t a h ighe r r a t e than hatchery f i s h t o t h e f i s h e r y upstream o f Gold Ray Dam because w i l d f i s h remain i n t h e r i v e r r a t h e r than enter Cole M. R ivers Hatchery.

INTRODUCTION

The Rogue R i v e r i s t h e l a r g e s t producer o f s p r i n g chinook salmon Oncorhynchus tshawytscha among r i v e r basins south o f t h e Col umbi a R iver . The s tock c o n t r i b u t e s t o commercial f i s h e r i e s o f f t h e coast o f no r the rn C a l i f o r n i a and Oregon (Jones 1988). Sa t te r thwa i t e (1987) est imated t h a t ocean 1 andings o f t h e 1971-76 brood years averaged about 60,000 w i l d f i s h annual ly . The s tock a1 so supports impor tan t r e c r e a t i o n a l f i s h e r i e s i n t h e Rogue R iver . Cramer e t a l . (1985) es t imated t h a t f reshwater h a r v e s t averaged about 7,000 a d u l t s annua l l y d u r i n g 1964-81. 'rhi s es t imate d i d n o t i nc lude j acks smal l e r than 60 cm (24 inches) .

I n recent years, f i s h e r y managers have expressed concern about t h e w i l d component o f t h e run . Product ion (ocean ca tch p l us f reshwater escapement) o f broods produced a f t e r t h e f i r s t 4 years o f f u l l ope ra t i on o f Lost Creek Dam a t r i v e r k i l ome te r (RK) 253 averaged 53% o f t h e produc t ion f rom preimpoundment broods (Sat te r thwa i t e 1987). A1 so, t h e re1 a t i v e abundance o f f a 1 1 ch inook salmon increased among w i l d a d u l t s t h a t entered areas upstream o f t h e count ing s t a t i o n a t Gold Ray Dam (RK 202) (Sat te r thwa i te 1987).

The s h i f t i n race composi t ion concerned f i s h e r y managers because t h e ea r l i e r - spawn ing s p r i n g race spawns i n o n l y a smal l p o r t i o n o f t h e basin, whereas t h e la te r -spawning f a l l race spawns i n a l a r g e p o r t i o n o f t h e bas in (Cramer e t a l . 1985). Some replacement of t h e s p r i n g race would occur i f f a l l ch inook salmon d i s turbed redds excavated by s p r i n g c h i nook salmon (McNeil 1964).

Surveys o f spawned carcasses i n t h e area upstream o f t h e mouth o f E l k Creek (RK 245) suggested t h a t w i l d females t h a t o r i g i n a t e d from post impoundment broods spawned 1 a t e r than w i l d females t h a t o r i g i n a t e d f rom preimpoundment broods ( S a t t e r t h w a i t e 1987). P r i o r t o t h e s t a r t o f f u l l ope ra t i on a t Los t Creek Dam, sp r i ng chinook salmon spawned most i n t e n s i v e l y i n t h i s area (Cramer e t a l . 1985). The l a t e r t ime o f spawning inay be t h e r e s u l t o f (1) f a l l chinook salmon spawning i n t h e area o r (2) l a t e r spawning by sp r i ng ch inook salmon. Seemingly, t h e r e should be l e s s concern i f t h e s p r i n g race was spawni ng 1 a t e r .

A l a t e r spawning t ime among sp r i ng chinook salmon has management i m p l i c a t i o n s . La te spawners do no t c o n t r i b u t e as w e l l as e a r l y spawners t o t he r i v e r f i s h e r i e s . Sa t te r thwa i t e (1987) repo r ted a c o r r e l a t i o n between m i g r a t i o n t ime and spawning t ime among chinook salmon produced be fore f u l l ope ra t i on began a t Los t Creek Dam. The r e l a t i o n s h i p i n d i c a t e d t h a t l a t e spawners migra ted i n t o t h e Rogue R ive r l a t e r than e a r l y spawners. Consequently, l a t e r spawning by s p r i n g chinook salmon may i n d i c a t e a l a t e r t i m e o f m ig ra t i on . L a t e r m i g r a t i o n would p robab ly decrease f reshwater harves t . Cramer e t a l . (1985) concluded t h a t e a r l y m i g r a t i n g a d u l t s c o n t r i b u t e d t o t h e r i v e r f i s h e r i e s a t a h ighe r r a t e than l a t e m i g r a t i n g a d u l t s .

To eva lua te these concerns, t h e Oregon Department o f F i sh and Wi ld1 i f e (ODFW) developed and conducted a study funded by t h e Un i ted Sta tes Army Corps o f Engineers (USACE). The study was designed t o (1) compare t h e spawning

d i s t r i b u t i o n and spawning t ime o f sp r i ng chinook and f a l l chinook salmon and (2) assess the e f f e c t o f Lost Creek Dam on t h e spawning d i s t r i b u t i o n and t h e spawning t ime o f chinook salmon.

Los t Creek Dam was completed i n 1976, bu t t h e r e s e r v o i r o n l y p a r t i a l l y f i l l e d d u r i n g 1977 because o f drought. Storage capac i t y o f t h e r e s e r v o i r i s 465,000 ac re - fee t , o f which about 180,000 a c r e - f e e t i s re leased d u r i n g the summer and fa1 1. A water i n t a k e s t r u c t u r e a1 lows f o r withdrawal f rom 5 l e v e l s when t h e r e s e r v o i r i s f u l l . S e l e c t i v e withdrawal permi ts some manipu la t ion o f water temperature h t re lease, p a r t i c u l a r l y when the r e s e r v o i r i s s t r a t i f i e d t

(USACE 1983). F l e x i b i 1 i t y i n re lease f l o w and water temperature prov ides t h e oppor tun i t y t o use re1 ease s t r a t e g i e s designed t o op t im ize product i o n and harvest of salmon and steelhead 0. mykiss i n downstream areas.

a

METHODS

We tagged chinook salmon t h a t passed Gold Ray Dam w i t h i n d i v i d u a l l y numbered tags, Dur ing 1974-78 and 1987 we used F loy t - b a r tags and i n 1986 we used aluminum jaw tags. We a l s o tagged adu l t s d u r i n g 1979-81, b u t we chose n o t t o analyze these data because t h e tags were n o t i n d i v i d u a l l y numbered and were color-coded by 2-week i n t e r v a l s . Chinook salmon t h a t passed Gold Ray Dam p r i o r t o 16 August were c l a s s i f i e d as sp r ing chinook salmon. L a t e r migrants were c l a s s i f i e d as f a l l chinook salmon based on tagg ing s tud ies a t t he t ime o f r i v e r e n t r y (Oregon Department o f F ish and WildlSfe, unpubl ished data) .

We recovered tags du r ing weekly surveys f o r spawned carcasses i n areas upstream o f Gold Ray Dam (Table 1). Upon recovery o f a tag, surveyors recorded t h e da te and t h e r i v e r k i l ome te r o f t h e recovery s i t e . We assumed t h a t tagged f i s h spawned i n c lose p r o x i m i t y t o t h e recovery s i t e .

Each week, surveyors walked 2 km up B i g Bu t te Creek from i t s conf luence w i t h t h e Rogue R ive r a t RK 250. Few chinook salmon spawn f a r t h e r upstream because o f a w a t e r f a l l t h a t u s u a l l y b locks f i s h m i g r a t i o n d u r i n g t h e e a r l y

Table 1. Areas surveyed f o r spawned carcasses o f chinook salmon t h a t migrated upstream o f Gold Ray Dam, 1974-87.

Area R iver

k i 1 ometer Survey* pe r iod

Gold Ray Dam pool - Tou Vel l e Park 205-212 Tou V e l l e Park - Dodge Br idge 212-223 Dodge Br ldge - Shady Cove 223-235 Shady Cove - Rogue-Elk Park 235-245 Rogue-El k Park - Hatchery 245-252

B i g B u t t e creeka 0 - 2

Years

1974-81, 1986-87 1974-81, 1986-87 1974-81, 1986-87 1974-81, 1986-87 1974-87

1974-81, 1986-87

a Enters the Rogue R iver a t RK 250.

f a l l . We used d r i f t b o a t s t o survey salmon carcasses i n t h e Rogue R iver . We surveyed a l t e r n a t e banks o f t h e channel on a l t e r n a t e weeks, except we surveyed every week i n areas where carcasses tended t o concentrate. We c u t a l l r e t r i e v e d carcasses i n h a l f t o (1 ) v e r i f y t h e sex o f t h e f i s h , and (2) prevent them from being counted du r ing succeeding surveys. Surveyors a l s o checked each carcass f o r tags o r c l i p p e d f i n s .

We est imated t h e spawning t ime o f w i l d female s p r i n g chinook salmon from weekly counts o f carcasses w i thou t f i n c l i p s . We assumed t h a t unmarked females o f hatchery o r i g i n d i d n o t b ias t h e data. Th i s assumption appeared reasonable because hatchery f i s h u s u a l l y accounted f o r l e s s than 10% o f t h e carcasses recovered d u r i n g surveys o f spawned carcasses (Appendix Tab1 es A- 1 and A-2).

We a l s o assumed t h a t carcasses were counted 2 weeks a f t e r spawning occurred. Th is assumption was based on a postspawning l o n g e v i t y o f 9 days (van den Berghe and Gross 1986) and a postmortem p e r i o d o f 5 days u n t i l d iscovery by a surveyor. A postmortem per iod o f 3.5 days would have been appropr ia te i f a l l areas were surveyed weekly. However, because some areas were surveyed on a1 t e r n a t e weeks, we selected 5 days as an approximation of t h e postmortem per iod .

We grouped da ta from unmarked carcasses o f spawned females i n t o preimpoundment and pos t impoundment broods. Because almost a1 1 w i l d femal es mature a t age 4 o r age 5 (Oregon Department o f F i sh and W i l d l i f e , unpubl ished data) , females counted du r ing 1974-79 were designated as preimpoundment broods and females counted d u r i n g 1981-87 were designated as postimpoundment broods. We grouped data f rom females t h a t spawned du r ing 1980 w i t h preimpoundment broods because age 5 a d u l t s were tw ice as abundant as age 4 a d u l t s (Cramer e t a l . 1985).

We used t h e spawning t ime o f females t h a t entered Cole M. R ivers Hatchery (RK 252) j u s t below Los t Creek Dam as a s t a t i s t i c a l c o n t r o l . Most of t h e females t h a t entered t h e hatchery du r ing 1975-77 were w i l d f i s h . By 1979, r e t u r n i o g females were most ly o f hatchery o r i g i n . Dur ing a l l years, hatchery personnel randomly se lec ted a d u l t s t o spawn. Consequently, spawning t ime a t t h e hatchery should accu ra te l y r e f l e c t spawning t ime had t h e a d u l t s been a l lowed t o spawn n a t u r a l l y ( telephone conversat ion on 20 February 1990 w i t h Michael Evenson, ODFW, Cole M. R ivers Hatchery, T r a i 1 , Oregon).

We made no at tempt t o es t imate the q u a n t i t y o r qua1 i t y o f phys i ca l h a b i t a t a v a i l a b l e t o e i t h e r j u v e n i l e o r a d u l t s p r i n g chinook salmon. We assumed t h a t temporal v a r i a t i o n s 5n channel morphology and phys ica l c h a r a c t e r i s t i c s o f t h e subs t ra te had no i n f l uence on e i t h e r spawning t ime o r spawning d i s t r i b u t i o n d u r i n g t h e t ime pe r iod o f t h e study. We recognize t h a t t h e h a b i t a t o f sp r i ng chinook salmon i s a dynamic, r a t h e r than s t a t i c , v a r i a b l e . However, o t h e r than water q u a l i t y , we lacked t h e data necessary t o eva lua te temporal changes i n h a b i t a t .

Flow and water temperature o f t he Rogue R i v e r was est imated f rom da ta recorded a t t h e automated gage near McLeod (RK 248) t h a t was operated by t h e Un i ted Sta tes Geological Survey. We used data on maximum water temperature i n analyses because mean water temperature was n o t est imated p r i o r t o 1979.

We chose P < 0.05 as a c r i t e r i a f o r s i g n i f i c a n c e . We used ana lys i s o f var iance t o tes t - fo r d i f f e r e n c e s between means. To i d e n t i f y re1 a t i onshi ps between v a r i abl es, we used c o r r e l a t i on ana lys i s and assumed da ta were random p a i r s o f observat ions from a b i v a r i a t e normal d i s t r i b u t i o n . To q u a n t i f y re1 a t i onships between var iab les , we used regress ion ana lys is . Independent v a r i a b l e s were assumed t o be measured w i thou t e r r o r . We used ana lys i s o f cova r i ance t o compare slopes and e l evat i ons o f regressions. E leva t i ons o f regress ions were n o t compared when the re were s i g n i f i c a n t d i f f e r e n c e s between reg ress ion slopes. Chi -square s t a t i s t i c s , w i t h c o r r e c t i o n s f o r c o n t i n u i t y where needed, were c a l c u l a t e d t o t e s t f o r d i f f e r e n c e s between d i s t r i bu t ions . We r e f e r r e d t o Snedecor and Cochran (1967) and Zar (1984) f o r a n a l y t i c a l procedures.

RESULTS

We recovered 561 tags from chinook salmon t h a t spawned upstream o f Gold Ray Dam. Annual recover ies o f tags ranged from a low o f 11 i n 1977 t o a h i g h o f 171 i n 1987. We recovered 260 tags from sp r ing chinook salmon t h a t o r i g i n a t e d from broods produced p r i o r t o t h e s t a r t o f L o s t Creek Dam operat ion. We a1 so recovered 213 tags from sp r ing c h i nook salmon produced du r ing t h e pos t i mpoundment years. However, t a g recove r ies from fa1 1 c h i nook salmon t o t a l e d o n l y 19 from broods reared i n preimpoundment years and 69 from broods reared i n postimpoundment years. A summary o f t a g recover ies i s presented i n Appendix Tables A-3 and A-4.

Spawning D is t r ibu t ion

The spawning d i s t r i b u t i o n o f fa1 1 chinook salmon overlapped t h e spawning d i s t r i b u t i o n o f sp r i ng chinook salmon i n the Rogue R ive r upstream o f Gold Ray Dam. Tag recover ies i n d i c a t e d t h a t t he over lap was g rea tes t i n t h e area downstream o f T r a i l Creek (RK 230). Few fa1 1 chinook salmon spawned i n areas f a r t h e r upstream (F igure 1). However, over lap i n spawning d i s t r i b u t i o n between sp r ing and t h e f a l l races increased when a d u l t s t h a t o r i g i n a t e d from post impoundment broods re tu rned t o spawn.

Tag recover ies from sp r ing chinook salmon i n d i c a t e d t h a t postimpoundment broods spawned f a r t h e r downstream than preimpoundment broods. Dur ing 1974-78, 48% o f t h e t a g recover ies came from the area c l o s e s t t o Los t Creek Dam (RK 241-252). During 1986-87, o n l y 31% o f t h e t a g recove r ies came from t h i s area. The d i f f e r e n c e i n d i s t r i b u t i o n o f t ag recover ies was s i g n i f i c a n t (P c 0.001). However, t h e r e was no s i g n i f i c a n t change i n t h e percentage o f f i s h t h a t spawned i n B i g B u t t e Creek (F igure 1) .

We d i d n o t de tec t a s i g n i f i c a n t change i n t h e spawning , d i s t r i b u t i o n o f f a l l chinook salmon. Adu l t s o f preimpoundment o r i g i n and a d u l t s o f pos t impoundment o r i g i n spawned i n t h e mainstem p r i m a r i l y between RK 205 and RK 217 (F igure 1). I n t h i s area, we found 68% o f t h e t o t a l tags recovered du r ing 1974-78 and 55% du r ing 1986-87. The d i f f e r e n c e between t h e samples was no t s i g n i f i c a n t (P = 0.58). Small samples s i zes (19 i n 1974-78 and 69 i n 1986-87) decreased t h e s e n s i t i v i t y o f t h i s ana lys is .

IN0 CHINOOK W O N

[tl PRUUPOUNDUENT BROODS POSllMPOUNDUEKT BROODS

FAU CHINOOK SALMON

Zi PREIMPOUNDMENT BROODS POSTIMPOUNDMENT BROODS

205-21 7 21 7-229 229-241 241 -253

RIVER KILOMETER ON ROGUE RIVER

BIG BUTTE CREEK

Figure 1. D i s t r i b u t i o n o f tags recovered from spawned carcasses o f chinook salmon. Preimpoundment broods were represented by f i s h tagged and recovered du r ing 1974-78. Post impoundment broods were represented by f i s h tagged and recovered du r ing 1986-87. Data were grouped so t h a t areas were o f s i m i l a r d is tance.

We found t h a t t h e l o c a t i o n o f spawning was r e l a t e d t o t h e t ime o f m i g r a t i o n a t Gold Ray Dam. Ear l y migrants tended t o spawn f a r t h e r upstream than l a t e migrants (APPENDIX B ) . The negat ive r e l a t i o n s h i p between t h e two v a r i a b l e s was s i g n i f i c a n t f o r each year except 1974 (Table 2 ) . Dur ing 1974, we were unable t o recover any tags from l a t e migrants t h a t passed Gold Ray Dam. C o r r e l a t i o n c o e f f i c i e n t s ranged between -0.47 and -0.53 f o r those years when we recovered a t l e a s t 10 tags from spawners t h a t passed Gold Ray Dam a f t e r 15 August (APPENDIX B) .

Table 2. Regressions o f r i v e r k i l ome te r o f t a g recovery (Y) on day o f tagg ing (X) f o r ch inook salmon tagged a t Gold Ray Dam and recovered as spawned carcasses. Day-of -year calendar i s i n APPENDIX D.

Year Regression SE o f s lope N r P

Regressions o f spawning l o c a t i o n on m ig ra t i on t i m i n g d i d no t d i f f e r s i g n i f i c a n t l y (P = 0.22 f o r slopes; P = 0.16 f o r e leva t i ons ) among brood years produced p r i o r t o t h e s t a r t o f Lost Creek Dam operat ion. Also, regressions o f spawning l o c a t i b n on migration t i m i n g d i d n o t d i f f e r s i g n i f i c a n t l y (P = 0.90 f o r slopes; P = 0.59 f o r e leva t i ons ) among postimpbundment broods. Consequently, we used pooled data from 1974-78 t o represent preimpoundment broods and used pooled da ta from 1986-87 t o represent postimpoundment broods.

We found t h a t t h e re1 a t i onsh i p between spawning l o c a t i o n and m i g r a t i o n t ime d i d n o t change a f t e r Lost Creek Dam began f u l l operat ion. E levat ions and slopes o f pooled regressions d i d n o t d i f f e r between preimpoundment and postimpoundment broods (Tab1 e 3 ) . We a1 so examined t h e mean k i l ome te r o f spawning o f f i s h tagged i n May and found no s i g n i f i c a n t d i f f e t e n c e (P = 0 . 7 3 ) between preimpoundment and postimpoundment broods, Because the re was no change i n the spawning l o c a t i o n o f e a r l y m ig ra t i ng adu l ts , we concluded t h a t a decrease i n r e l a t i v e abundance o f e a r l y m ig ra t i ng ad l l l t s was respons ib le f o r t he downstream s h i f t i n spawning d i s t r i b u t i o n among a l l sp r i ng chinook salmon.

Analys is o f t h e spawning d i s t r i b u t i o n o f w i l d female chinook salmon a l s o i n d i c a t e d t h a t t h e spawning d i s t r i b u t i o n o f sp r i ng chinook salmon s h i f t e d downstream a f t e r t h e j u v e n i l e s produced a f t e r f u l l ope ra t i on began a t Los t Creek Dam re turned t o spawn. Among w i l d females t h a t o r i g i n a t e d from preimpoundment broods, an average o f 54% spawned upstream o f E l k Creek. Among counterpar ts t h a t o r i g i n a t e d from postimpoundment broods, an average o f 40%

spawned upstream o f E l k Creek. The d i f f e r e n c e i n means was s i g n i f i c a n t (P = 0.015) and agreed w i t h r e s u l t s o f ana l ys i s o f tagged f i s h .

Table 3. Regressions o f r i v e r k i l ome te r o f carcass recovery (Y) on day of passage a t Gold Ray Dam (X) f o r chinook salmon, preimpoundment broods (1974-78 r e t u r n s ) compared w i t h postimpoundment broods (1986-87 r e t u r n s ) . Day-of -year ca lendar i s i n APPENDIX D.

P f o r d i f f e r e n c e e Years N Regression SE o f s lope r Elevat ions Slopes

Resu l ts from c o r r e l a t i o n analyses o f f a c t o r s t h a t cou ld have i n f l uenced the spawning d i s t r i b u t i o n o f w i l d females were i nconc lus i ve . Annual est imates o f t h e percentage o f females t h a t spawned upstream o f E l k Creek c o r r e l a t e d s i g n i f i c a n t l y w i t h (1) f l o w d u r i n g m ig ra t i on , (2 ) f l o w d u r i n g spawning, and (3) water temperature d u r i n g spawning (Table 4 ) . S i g n i f i c a n t c o r r e l a t i o n s among most o f t he v a r i a b l e s made i t d i f f i c u l t t o i d e n t i f y f a c t o r s t h a t i n f l uenced t h e spawning d i s t r i b u t i o n o f w i l d ch inook salmon t h a t spawned upstream o f Gold Ray Dam.

Table 4. C o r r e l a t i o n m a t r i x o f va r i ab les used i n analyses o f spawning d i s t r i b u t i o n o f w i l d female chinook salmon, 1974-87.

Spawn i ng F,1 ow Water temperature d i s t r i bu t i ona M ig ra t i onU SpawningL SpawningU incubatione

Spawning d i s t r i b u t i o n 1. OOf M i g r a t i o n f l o w -0.87f 1. 0Of Spawning f 1 ow -0. 67f 0.63f 1. OOf Spawning temperature 0.80 -0.81 -0.80 1 .OO Incubat ion temperature -0.49 0.53 0.35 -0.44 1 .OO

t

a Percent o f w i l d females t h a t spawned upstream o f E l k Creek. Mean f low ( c f s ) near dcLeod dur ing August. . dean f l o w ( c f s ) near McLeod dur ing Septefiber-October. Mean maximum water temperature ("C) near McLeod dur ing September-October. Mean maximum water temperature ("C) near McLeod dur ing October-January i n year i - 4 (per iod t h a t eggs and a lev ins incubated i n redds) . P 0 . 0 5 i n t w o - t a i l e d t e s t .

Water temperature f o u r years e a r l i e r when f i s h incubated i n t h e gravel as eggs and a l e v i n s was n o t c o r r e l a t e d w i t h spawning d i s t r i b u t i o n o f w i l d females (Table 4) . This f i n d i n g suggested t h a t r i v e r phys ica l f a c t o r s t o which a d u l t s were exposed p r i o r t o and du r ing spawning had a g r e a t e r i n f l u e n c e on spawning d i s t r i b u t i o n compared w i t h environmental f a c t o r s t o which t h e broods were exposed d u r i n g the incubat ion per iod . Data inc luded i n these analyses are presented i n Appendix Table A-5.

Spawning d i s t r i b u t i o n o f chinook salmon was l e s s r e l a t e d t o spawning t ime than t o m i g r a t i o n t ime. A ~ n n g tagged f i s h , spawning l o c a t i o n c o r r e l a t e d s i g n i f i c a n t l y w i t h spawning t ime i n th ree o f t he seven years t h a t we sampled (Table 5). I n con t ras t , spawning l o c a t i o n c o r r e l a t e d s i g n i f i c a n t l y w i t h m ig ra t i on t i m i n g i n s i x o f seven years (Table 2 ) . Comparisons o f c o r r e l a t i o n c o e f f i c i e n t s i nd i ca ted t h a t spawning d i s t r i b u t i o n was more h i g h l y r e l a t e d t o m i g r a t i c n t inie than spawning t ime f o r tagged f i s h recovered from preimpoundment broods ( Z = 3.05) and postimpoundment broods ( Z = 4.46) .

Table 5. Co r re la t i ons o f r i v e r k i lometer o f t a g recovery and day o f t a g recovery f o r chinook salmon tagged a t Gold Ray Dam and recovered as spawned carcasses,

! Year N r P

Spawni ng Time

Analys is o f t a g recover ies i nd i ca ted t h a t t h e spawning t ime o f f a l l chinook salmon overlapped t h e spawning t ime o f sp r i ng chinook salmon f o r postimpoundment broods t h a t spawned i n t h e area between t h e pool behind Gold Ray Dam and T r a i l Creek (RK 205-240). I n t h i s area, bo th races o f chinook salmon spawned p r i m a r i l y between l a t e September and t h e end o f October (F igure 2) , and peaked du r ing the second week o f October. Tag recover ies i n d i c a t e d t h a t f a l l chinook salmon spawned an average o f 5 days l a t e r than sp r ing chinook salmon. We d i d n o t est imate t h e spawning t ime o f f a l l chinook salmon i n t h e area f a r t h e r upstream because few spawned upstream o f T r a i l Creek. Also, we d i d no t est imate t h e spawning t ime o f f a l l chinook salmon t h a t o r i g i n a t e d from preimpoundment broods because few spawned upstream o f Gold Ray Dam (Sat ter thwai t e 1987).

Combined t a g recover ies from a l l areas i n d i c a t e d t h a t among sp r ing chinook salmon, a d u l t s t h a t o r i g i n a t e d from post impoundment broods spawned

GZi SPRING CHINOOK W O N FALL CHINOOK W O N

I SEPTEMBER I

OCTOBER I

F igu re 2. Estimated spawning t ime o f chinook salmon t h a t o r i g i n a t e d f rom post impoundment broods. Data were from tagged carcasses recovered downstream o f T r a i l Creek, 1986-87.

l a t e r than adu l t s t h a t o r i g i n a t e d from preimpoundment broods (F igure 3 ) . Among preimpoundment broods, spawning peaked du r ing 1 a te September. Spawning by postimpoundment broods peaked 2 weeks l a t e r . From these t a g recover ies , we est imated t h a t 70% o f t h e preimpoundment broods spawned du r ing September, compared w i t h o n l y 38% o f t h e postjmpoundment broods.

Counts o f unmarked carcasses a l so i nd i ca ted t h a t spr ing chinook salmon o r i g i n a t i n g from postimpoundment broods spawned l a t e r than preimpoundment broods (F igure 4) . I n t h e area c l o s e s t t o Lost Creek Dam (RK 245-252), spawning by preimpoundment broods peaked dur ing the midd le o r l a t e r p o r t i o n o f September, whi 1 e spawning by postimpoundment broods peaked d u r i n g e a r l y October. Time o f spawning i n t h e RK 235-245 area a l so peaked l a t e r , bu t t he change was 1 week r a t h e r than 2 weeks (F igure 4 ) . Because tagg ing s tud ies showed t h a t few f a l l chinook salmon spawned i n these areas, l a t e r spawning by sp r ing chinook salmon must be respons ib le f o r t h e change i n spawning t ime.

Among sp r ing chinook salmon spawning i n B i g Bu t te Creek, postimpoundment broods a l so spawned l a t e r than preimpoundment broods (F igure 4 ) . We es t imated t h a t an average o f 52% o f t h e postimpoundment broods spawned d u r i n g September, compared w i t h an average o f 34% o f t h e preimpoundment broods. Spawning of postimpoundment broods peaked 1 week l a t e r than preimpoundment broods (F igure 4) . Data i nc luded i n analyses o f data from unmarked carcasses i n a l l areas are presented i n Appendix Tables A-6 through A-8.

I SPRING CHINOOK SALMON PREIMPOUNDMENT 8ROODS I POSTlUPOUNDMENt BROODS

1 SEPTEMBER 1

OCTOBER I

F igu re 3. Estimated spawning t ime o f sp r i ng chinook salmon based on tagged carcasses recovered i n a l l areas. Preimpoundment broods were represented by f i s h tagged and recovered d u r i n g 1974-78. Postimpoundment broods were represented by f i sh tagged and recovered du r ing 1986-87.

Annual est imates o f t h e mean t ime of spawning f o r unmarked sp r ing chjnook salmon ranged between l a t e September and e a r l y October 5n 859 B u t t e Cree'k and i n t h e two areas o f t h e Rogue R i v e r (F igure 5) . These data a l s o showed t h a t postimpoundment broods spawned l a t e r than preimpoundment broods. Mean tSme o f spawning was s i g n i f i c a n t l y 1 a t e r f o r postimpoundment broods spawning in t h e mainstem (P = 0.004 f o r RK 235-245 and P < 0.001 f o r RK 245-252).

We d i d no t de tec t a s i g n i f i c a n t d i f f e r e n c e (P = 0.113 Sn t h e mean t i m e o f spawning between preimpoundment and postimpoundment broods t h a t spawned i n B?g B u t t e Creek (F igure 5) . F a i l u r e t o d e t e c t a d i f f e r e n c e may have been r e l a t e d t o smal l sample sizes. A s e n s i t i v i t y ana lys i s suggested t h a t we would have detec ted a change had we sampled 2 more years when postimpoundment broods spawned i n B i g B u t t e Creek, p rov ided t h a t t ime o f spawning was s i m i l a r t o t h e o t h e r 3 years we sampled. Data inc luded i n these analyses a r e presented i n Appendix Tab1 e A-9.

We a l so found no s i g n i f i c a n t change i n t h e ,median da te o f spawning by females t h a t re tu rned annua l ly t o Co le M. R ivers Hatchery (P = 9.185). The median date o f spawning averaged 5 October f o r females t h a t r e t u r n e d d u r i n g 1975-80. Dur ing 1901-87, t h e median d a t e o f spawnCng by females t h a t en tered t h e hatchery averaged 3 October. Based on these r e s u l t s , v e conclude t h a t a decreased su rv i va l crate among progeny o f e a r l y spawning a d u l t s was t h e f a c t o r t h a t caused l a t e r spawning among w i l d a d u l t s produced f rom ,postimpoundment broods. Data used i n t h i s ana lys i s are presented i n Appendix Table A-10.

I

not sampled - I I SEPTEMBER OCTOBER

f i g u r e 4 . Estimated spawning t ime o f spring chinook salmon based on counts o f unmarked carcasses o f spawned females. F i s h recovered dur ing 1974-80 composed preimpoundment broods. F i s h recovered dur ing 1981-87 composed postimpbundment broods.

- -

- P i

P Q P -

4 0 not sampled - r-

Figure 5. Estimated mean date of spawning for spring chinook salmon based on the count of unmarked carcasses. Open circles represent preimpoundment broods and closed circles represent postimpoundment broods. Brackets represent 95% confidence intervals associated with the means.

-

-

-

-

10/10 -

10/05 -

09/30 -

09/25 -

BIG BUTTE CREEK

P I I !I

P i! not sampled

I I I I I I I I I I 1 I I I

We found a s i g n i f i c a n t r e l a t i o n s h i p (r = 0.89, P < 0.001) between water temperature du r ing t h e p e r i o d eggs and a lev ins incubate i n t h e grave l and t h e mean date o f spawning by w i l d female spr ing chinook salmon i n t h e Rogue R ive r upstream o f E l k Creek. The p o s i t i v e r e l a t i o n s h i p i n d i c a t e d t h a t a d u l t s spawned l a t e r when cohor ts were exposed t o increased water temperature f o u r years e a r l i e r du r ing i ncuba t i on . Physical parameters o f t h e r i v e r , i n c l u d i n g f low d u r i n g t h e p e r i o d o f a d u l t m igra t ion , and f l o w and water temperature d u r i n g spawning, were n o t s i g n i f i c a n t l y c o r r e l a ted w i t h spawning t ime. Data used i n these analyses are presented i n Appendix Tables A-5 and A-9.

Ana lys is o f t a g recover ies showed t h a t spawning t ime c o r r e l a t e d p o s i t i v e l y w i t h m i g r a t i o n t ime a t Gold Ray Dam. E a r l y migrants tended t o spawn ea r l y , w h i l e l a t e migrants tended t o spawn l a t e r (APPENDIX C) . Regressions of spawning t ime on m i g r a t i o n t ime were s i g n i f i c a n t f o r each o f t h e 7 years o f tagg ing (Tab1 e 6).

Table 6. Regressions o f day o f t a g recovery (Y) on day o f tagg ing (X) f o r chinook salmon tagged a t Gold Ray Dam and recovered as spawned carcasses. Day-of-year ca lendar i s i n APPENDIX D.

Year Regression SE o f s lope N r P

Regressions of spawning t ime on m ig ra t i on t ime d i d n o t d i f f e r (P = 0.08 f o r slopes and 0.12 f o r e leva t i ons ) among preimpoundment broods. A1 so, regressions o f spawning t ime on m ig ra t i on t ime d i d n o t d i f f e r (P = 0.57 f o r slopes and 0.17 f o r e l e v a t i ons) among post impoundment broods. Consequently, we pooled da ta from 1974-78 t o represent preimpoundment broods and pooled data from 1986-87 t o represent pos t impoundment broods.

We found t h a t t h e r e l a t i o n s h i p between spawning t ime and m i g r a t i o n t ime changed a f t e r Lost Creek Dam became opera t iona l . Slopes o f pooled preimpoundment and pos t impoundment regressions d i f f e r e d s i g n i f i cant1 y (Table 7) . To make these f i n d i n g s eas ie r t o i n t e r p r e t , we used preimpoundment and postimpoundment regress ions t o p r e d i c t t h e mean date o f carcass recovery f o r sp r i ng chinook salmon t h a t passed Gold Ray Dam on f o u r dates rep resen ta t i ve o f m i g r a t i o n t im ing .

Resu l ts Sndicated t h a t spawning t ime changed f o r sp r i ng chinook salmon t h a t passed Gold Ray Dam from May through e a r l y J u l y (F igure 6). Spawning t ime d i d n o t change f o r a d u l t s t h a t migrated du r ing l a t e J u l y and August. The

Table 7. Regressions o f day o f carcass recovery (K) and day o f passage a t Gold Ray Dam ( X ) f o r chinook salmon, preimpoundment broods (1974-78 r e t u r n s ) compared w i t h pos t i mpoundment broods (1986-87 re tu rns ) . Day-of -year c a l endar i s i n APPENDIX D.

Years N P f b r d i f f e r e n c e

Regression SE o f slope r Eleva t i ons Slopes

1 0/31 -*

0 PREIMPOUNDMENT BROODS POSTlMPOUNbMENT BROODS

DATE OF MIGRATION AT GOLD RAY DAM

F igu re 6. Predic ted mean date o f carcass recovery f o r spr ing chinook salmon passing Gold Ray Dam on f o u r dates encompassing t h e per iod o f migra t ion . Preimpbundment broods (p red i c ted from 1974-78 data) are compared w i t h postimpoundment broods (p red i c ted from 1986-87 da ta ) . Brackets represent 95% conf idence i n t e r v a l s associated w i t h t h e pred ic ted values.

change i n spawning t ime was most ev ident among e a r l y migrants. We est imated t h a t among adu l t s t h a t passed Gold Ray Dam on 1 May, postimpoundment broods spawned an average o f 12 days l a t e r compared w i t h preimpaundment broods. I n con t ras t , along adu l t s t h a t migrated on 1 Ju ly , t h e regressions p red i c ted t h a t post i mpoundment broods spawned an average of 5 days 1 a t e r than p r e i mpoundment

broods. These changes caused t h e temporal d i s p a r i t y i n spawning t ime between e a r l y and l a t e m ig ra t i ng a d u l t s t o be l e s s among postimpoundment broods than preimpoundment broods (F igure 6) .

DISCUSSION

We found t h a t t h e spawning d i s t r i b u t i o n of s p r i n g chinook salmon and f a l l ch inook salmon overlapped i n the Rogue R iver upstream o f Gold Ray Dani. Both races spawned i n t h e area between t h e r e s e r v o i r behind Gold Ray Dam and T r a i l Creek. Many sp r ing chinook salmon, bu t few f a l l chinook salmon, spawned upstream o f T r a i l Creek. Overlap i n t h e spawning d i s t r i b u t i o n o f bo th races increased a f t e r Los t Creek Dam began f u l l ope ra t i on because sp r ing chinook salmon from post impoundment broods spawned f a r t h e r downstream than preimpoundment broods.

F a l l chinook salmon spawned i n areas used by la te-spawning sp r ing chinook salmon. Because t h e d i f f e r e n c e i n spawning t ime between t h e races averaged l e s s than 5 days, we b e l i e v e t h a t few redds o f s p r i n g chinook salmon were d i s tu rbed by f a l l chinook salmon. This b e l i e f i s based on t h e assumption t h a t female s p r i n g chinook salmon spent 14 days a t t h e s i t e o f t h e i r redd and prevented o the r females from spawning a t t h a t s i t e ( N e i l son and Banford 1983).

Fishery managers should be concerned about f a l l chinook salmon spawning i n con junc t i on w i t h s p r i n g chinook salmon. I n t h e Rogue R ive r basin, sp r i ng chinook salmon spawn o n l y i n t h e area upstream of Gold Ray Dam. I n con t ras t , f a l l chinook salmon spawn i n w ide l y d i s t r i b u t e d areas throughout t h e Rogue R ive r bas in (Cramer e t a1 . 1985). With increased spawning between races, r a c i a l d i f f e r e n c e s i n m i g r a t i o n t i m i n g a t Gold Ray Dam may become l e s s d i s t i n c t . A g rea te r p r o p o r t i o n o f w i l d sp r i ng chinook salmon may migra te du r ing July-August r a t h e r than du r ing May-June. Such a s h i f t i n m i g r a t i o n t i m i n g i s no t w i thou t precedence among chinook salmon ( S l a t e r 1963; Kwain and Thomas 1984).

Pro t rac ted i n t e r r a c i a l spawning would probably l e a d t o a d e c l i n e i n t h e f reshwater harvest o f sp r i ng chinook salmon i n t h e Rogue R iver . Late m i g r a t i n g a d u l t s c o n t r i b u t e a t lower r a t e s t o t h e r i v e r f i s h e r i e s compared w i t h e a r l y migrants. E a r l y migrants pass through the f i s h e r y i n t h e lower r i v e r (RK 5-43) a t a t ime o f opt imal f l o w f o r harves t (Cramer e t a l . 1985). E a r l y migrants a l s o c o n t r i b u t e b e t t e r than l a t e migrants t o the f i s h e r y upstream o f Gold Ray Dam because o f a longer p e r i o d o f res idence w i t h i n t h e area o f t h e f i s h e r y .

We fo~ lnd t h a t a d u l t s t h a t o r i g i n a t e d from post impoundment broods spawned f a r t h e r downstream i n t h e Rogue R iver than a d u l t s t h a t o r i g i n a t e d from preimpoundment broods. Hawever, a s im i 1 a r percentage o f p r e i mpoundment and pos t impoundment broods spawned i n B ig But te Creek. Th i s f i n d i n g suggested t h a t ope ra t i on o f Los t Creek Dam was respons ib le f o r t h e downstream s h i f t i n t h e spawning d i s t r i b u t i o n o f sp r i ng chinook salmon i n t h e Rogue River .

We a1 so found t h a t a d u l t s t h a t o r i g i n a t e d f rom postimpoundment broods spawned 1 a t e r than a d u l t s t h a t o r i g i n a t e d from preimpoundment broods. The change i n spawning t ime was g r e a t e s t i n t he area immediately downstream o f Los t Creek Dam and d imin ished w i t h d is tance downstream. Although n o t as

pronounced as i n t h e mainstem, we a l so noted a l a t e r spawning t i m e f o r a d u l t s i n B ig B u t t e Creek. The simultaneous change i n spawning t ime f o r a d u l t s i n t h e mainstem and i n B i g B u t t e Creek suggested t h a t ope ra t i on o f Los t Creek Dam may n o t have been respons ib le f o r t h e change i n t h e spawning t ime o f sp r i ng chinook salmon.

The p o s s i b i l i t y t h a t Lost Creek Dam d i d no t change t h e spawning t ime o f w i l d s p r i n g chinook salmon assumes t h a t few, i f any, o f t h e f r y produced i n t h e mainstem st rayed as a d u l t s and spawned i n B i g Bu t te Creek, Because some s t r a y i n g may have occurred, we 2 lso examined t h e spawning t ime o f female s p r i n g chinook salmon t h a t re tu rned t o Cole M. Rivers Hatchery. Because t h e spawning t ime o f w i l d a d u l t s charrged, w i thou t a simultaneous change i n t h e spawning t ime o f a d u l t s t h a t re tu rned t o t h e hatchery, we concluded t h a t environmental cond i t i ons d u r i n g t h e l a s t few months p r i o r t o spawning were n o t respcns ib le f o r t h e change i n spawning t ime o f w i l d adu l ts .

Dur ing e a r l i e r work, we found t h a t t h e opera t ion o f t h e dam d i d n o t a f f e c t t h e spawning t ime o r spawning d i s t r i b u t i o n o f broods produced d u r i n g preimpoundment years t h a t re tu rned t o spawn i n post impoundment years (Cramer e t a1 . 1985). The change i n spawning t ime and spawning d i s t r i b u t i o n o f broods produced du r ing postimpoundment years l e d us t o conclude t h e r e was a change i n t h e gene t i c composit ion o f t he stock. Changes i n s u r v i v a l r a t e o f j u v e n i l e s o r a d u l t s a f f e c t e d t h e gene t i c composit ion o f t h e stock, and a l t e r e d l i f e h i s t o r y c h a r a c t e r i s t i c s . S e l e c t i v e breeding p r a c t i c e s among hatchery stocks i s a good example o f such a mechanism (La rk in 1981).

We b e l i e v e t h a t decreased s u r v i v a l among t h e progeny o f sprSng chinook salmon t h a t migrated e a r l y r e s u l t e d i n a downstream s h i f t i n spawning d i s t r i b u t i o n among cohor ts t h a t surv ived t o spawn. Thi s concl us ion was based on t h e f i n d i n g t h a t e a r l y migrants spawned f a r t h e r upstream than 1 a te migrants. The decrease i n t he r e l a t i v e abundance o f e a r l y migrants r e s u l t e d 5n an increase i n t h e r e l a t i v e abundance o f l a t e migrants t h a t spawn i n areas f a r t h e r downstream.

We a l s o be l i eve t h a t decreased s u r v i v a l among t h e progeny o f e a r l y migrants r e s u l t e d i n a l a t e r t ime o f spawning among cohor ts t h a t surv ived t o spawn. Th is conclus ion was based on the f i n d i n g t h a t e a r l y migrants spawned e a r l i e r than l a t e migrants. The decrease i n t he re1 a t i v e abundance o f e a r l y migrants r e s u l t e d i n an increase i n t h e r e l a t i v e abundance o f l a t e migrants t h a t spawn l a t e r .

The r e l a t i v e abundance o f e a r l y migrants cou ld have decreased because o f increased r a t e o f a d u l t m o r t a l i t y . Although t h e r a t e o f na tu ra l m o r t a l i t y i n t h e r i v e r d i d no t increase a f t e r Lost Creek Dam became opera t iona l (Cramer e t a1 . 1985), t h e r a t e o f f i s h i n g mor ta l i t y i n t h e r i v e r probably increased d u r i n g 1974-87. Angler e f f o r t increased g r e a t l y d u r i n g t h a t p e r i o d (telephone conversa t ion on 22 November 1989 w i t h Michael Jenni ngs, ODFW, Roseburg, Oregon). I n add i t i on , t h e c l o s i n g date f o r t h e f i s h e r y i n t h e area upstream o f Gold Ray Dam changed from 15 J u l y d u r i n g 1973-77 t o 31 J u l y d u r i n g 1978-87. Because e a r l y migrants res ided i n t h e area o f t h e f i s h e r y f o r a longer pe r iod o f t ime than l a t e migrants, increased f j s h i n g e f f o r t may have caused a d i sp ropo r t i ona te increase i n t he harvest o f e a r l y migrants compared w i t h l a t e migrants.

Cramer e t a7. (1985) est imated t h a t anglers harvested 33% o f the sp r ing chinook salmon t h a t passed Gold Ray Dam dur ing 1981. Ac tua l l y , harvest r a t e s cou ld have been 50% and 10% f o r adu l t s t h a t passed Gold Ray Dam dur ing May and Ju ly , respec t i ve l y . Unfor tunate ly , we do no t have t h e data needed t o assess t h e p o t e n t i a l f o r d i f f e r e n t i a l harvest ra tes . To determine t h e r e l a t i o n s h i p between m ig ra t i on t i m i n g and harvest ra te , an i n t e n s i v e study i n c l u d i n g tagging, prespawning m o r t a l i t y surveys, and angler surveys throughout the f i s h e r y upstream o f Gold Ray Dam would have t o be conducted.

D i f f e r e n t i a1 product ion of j u v e n i l e s from d i f f e r e n t groups o f spawners i s another fac to r t h a t might be respons ib le for t he change i n the spawning t ime and spawning d i s t r i b u t i o n o f sp r ing chinook salmon. A 1 ocal i z e d decrease i n juven i 1 e product ion could decrease t h e l o c a l i zed abundance o f cohorts t h a t re turned t o spawn because anadromous salmonids tend t o spawn i n n a t a l areas (Ricker 1972; H o r r a l l 1981). Factars pos tu la ted t h a t might have decreased j u v e n i l e product ion i n t h e l o c a l i zed area downstream from Lost Creek Dam inc luded (1) changes i n spawning hab i ta t , (2) redd dewatering, and (3) increased water temperature du r ing the autumn and e a r l y w in te r .

/

Q u a l i t y o f spawning h a b i t a t f o r spr ing chinook salmon might have decreased because o f increased r a t e s o f armoring o r sedimentat ion o f gravel . The q u a n t i t y o f spawning h a b i t a t may have decreased w i t h cessat ion o f g rave l recru i tment from areas upstream o f t h e dam. We be1 ieve such changes, i f they occurred, would develop gradua l ly . I n con t ras t , observed changes i n spawning t ime and spawning d i s t r i b u t i o n o f spr ing chinook salmon were abrupt, and exhi b i t ed minimal v a r i a t i o n among post impoundment broods.

We are more c e r t a i n t h a t redd dewatering was no t respons ib le f o r changes i n spawning t ime and spawning d i s t r i b u t i o n o f sp r ing chinook salmon. Flow augmentation du r ing spawning d i d no t begin u n t i l 1981, y e t changes i n spawning parameters were ev ident among the 1977-80 broods. Consequently, we be1 ieve t h a t increased water temperature i s the more l i k e l y f a c t o r respons ib le f o r t he r e l a t i v e decrease o f t he e a r l y spawning p o r t i o n o f t h e run.

Sa t te r thwa i te (1987) est imated t h a t t he opera t ion o f Lost Creek Dam decreased product ion o f sp r ing chinook salmon f r y by an average o f 33% annual l y dur ing 1977-85. Increased water temperature du r ing t h e t ime t h a t eggs and a lev ins incubated i n the gravel was i d e n t i f i e d as a poss ib le causal f a c t o r . Increased water temperature, which r e s u l t e d i n an accelerated r a t e o f development o f eggs and a lev ins , caused spr ing chinook salmon f r y t o emerge e a r l i e r than they would have under na tu ra l cond i t i ons (Cramer e t a1 . 1985). Studies o f coho salmon i n Oregon coasta l streams a l s o imp l i ca ted e a r l y emergence as a cause o f decreased product ion (N icke l son e t a1 . 1986).

If e a r l y emergence decreased t h e product ion o f sp r ing chinook salmon f r y i n t h e Rogue River, t h e e f f e c t would have been g rea tes t near Los t Creek Dam. Simulat ions o f water temperature by the USACE ind ica ted t h a t t h e opera t ion o f Los t Creek Dam increased water temperature du r ing the incubat ion pe r iod (November-January) by an average of 2.0°C a t RK 248 and by an average o f 1.3"C a t RK 202. Resul tant d i f f e r e n c e s i n j u v e n i l e product ion may have caused subsequent s p a t i a l and temporal d i f fe rences i n t h e number o f cohor ts t h a t surv ived t o spawn.

Also, i f e a r l y emergtince decreased f r y product ion, t h e e f f e c t would be g r e a t e s t on eggs deposi ted by e a r l y spawners. A lower r a t e o f s u r v i v a l among progeny o f e a r l y spawning parents would be r e f l e c t e d i n a l a t e r t5me o f spawning among adu l t s t h a t surv ived t o Spawn, as we observed. Tay lo r (1980) found s t rong h e r i t a b i l i t y i n t h e spawning t ime o f p i n k salmon. Progeny o f e a r l y spawning parents spawned e a r l i e r than t h e progeny o f l a t e r spawning parents. The t ime of matura t ion i s dependent p r i m a r i l y on a g e n e t i c a l l y based response t o t h e amount o f d a y l i g h t hours. A l t e r a t i o n o f t h e photoper iod changed t h e spawning t ime of sp r i ng chinook salmon h e l d i n a ha tchery (Zaugg e t a l . 1986).

Many researchers have hypothesized t h a t t he v a r i e d spawning t ime among stocks o f P a c i f i c salmon i s a g e n e t i c a l l y based adapta t ion t o l o c a l i z e d regimes o f water temperature d u r i n g t h e pe r iod t h a t eggs and a lev lns incubate i n t h e grave l (Bams 1969; R icker 1972; Godin 1981; M i l l e r and Brannon 1981). Assuming t h a t t h i s hypothesis i s t rue , then l a t e r spawnlng by sp r ing chinook salmon i n t h e Rogue R i v e r would compensate f o r t h e e a r l y emergence of f ry caused by increased water temperature du r ing t h e t ime t h a t eggs and a l e v i n s incubate i n t h e g rave l . Because t h e increase i n water temperature d imin ished w i t h d i s tance downstream, one would expect t h a t any change i n spawning t ime would a l s o d im in i sh w i t h d is tance downstream, which i s what we observed i n t h i s study.

The l a t e r t ime o f spawning may no t have been accompanied by a l a t e r t ime o f m i g r a t i o n among w i l d adu l t s . Unfor tunate ly , we cou ld no t evaluate t h e m i g r a t i o n t i m i n g o f postimpoundment broods t h a t passed Gold Ray Dam. The h igh percentage o f unmarked f i s h among hatchery a d u l t s prevented us from c o n f i d e n t l y es t ima t ing m i g r a t i o n t i m i n g o f w i l d a d u l t s separa te ly from hatchery adu l ts .

Recent changes i n o u t f l o w temperature from Lost Creek Dam may s h i f t t h e spawning o f sp r i ng chinook salmon t o a s p a t i a l and temporal d i s t r i b u t i o n more 1 i ke t h e d i s t r i b u t i o n o f preimpoundment broods. Since t h e f a l l o f 1984, re lease temperature d u r i n g incubat ion o f eggs and a l e v l n s decreased compared w i t h re lease temperature d u r i n g postimpoundment years. I f an increase i n f r y p roduct ion and subsequent a d u l t r e t u r n s occurs because eggs and a1 e v i ns develop a t a slower r a t e , then an increase i n t h e r e l a t i v e abundance o f e a r l y spawners should occur i n t h e v i c i n i t y o f Los t Creek Dam.

We a re now eva lua t i ng t h e ef fect of mod i f ied water temperature on t h e product fon o f sp r i ng chinook salmon. As p a r t of t h i s p r o j e c t , we a r e es t ima t ing the abundance o f w i l d sp r i ng chinook salmon and w i l d f a l l ch inook salmon t h a t migra te upstream o f Gold Ray Dam. If we f i n d no increase i n t h e r e l a t i v e abundance o f t h e sp r ing race compared w i t h t h e f a l l race, then a f a c t o r ( s ) o t h e r than incubat fon temperature i s l i k e l y respons ib le f o r t he downstream s h i f t i n spawning d i s t r i b u t i o n and spawning t ime noted f o r t h e f i r s t postimpoundment broods.

ACKNOWLEDGEMENTS

We thank t h e numerous seasonal personnel who ass i s ted w i t h t h e f i e l d work. We a l so thank Michael F lesher and W i l l i a m No11 f o r l ead ing sampling

crews du r ing most of t he study. Mary Buckman, Wayne Burck, L y l e Ca lv in , Alan McGie, and several anonymous i n d i v i d u a l s reviewed and improved t h e r e p o r t w i t h t h e i r comments.

REFERENCES

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Godin, J-G.J. 1981. M ig ra t i ons o f salmonid f i s h e s d u r i n g e a r l y l i f e h i s t o r y phases: d a i l y and annual t im ing . Pages 22-50 in E.L. Brannon and E.O. Salo, e d i t o r s . Proceedings o f a symposium on salmon and t r o u t m ig ra to ry behavior. U n i v e r s i t y o f Washington, Sea t t l e .

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APPENDIX A

Tables o f Data Re la t ing t o Studies o f Chinook Salmon

Appendix Tab1 e A-1. Estimated composition o f spawned carcasses o f female chinook salmon found i n the Rogue River between Gold Ray Dam and Shady Cove, 1974-87. The area was not surveyed dur lng 1982-85.

RK 205-212 RK 212-223 RK 223-235 Year Wild Hatchery W i l d Hatchery W i l d Hatchery

Appendix Table A-2. Estimated composi t I o n of spawned carcasses o f female chinook salmon found i n the Rogue River between Shady Cove and Cole M. Rivers Hatchery, and i n B ig Butte Creek, 1974-87.

RK 235-245 RK 245-252 B ig But te Creek Year Wild Hatchery Wild Hatchery W i 1 d Hatchery

Appendix Table A-3. D i s t r i b u t i o n o f tagged s p r i ~ g chinook salmon recovered as spawned carcasses i n t h e Rogue R iver basin, 1974-78 and 1986-87. Data were grouped so t h a t areas o f t h e mainstem were o f s i m i l a r d is tance.

R i v e r k i l ome te r o f t he Rogue R ive r B i g Bu t te Year 205-216 217-228 229-240 241-252 Creek

Appendix Table A-4. D i s t r i b u t i o n o f tagged fa1 1 chinook salmon recovered as spawned carcasses i n t h e Rogue R ive r basin, 1974-78 and 1986-87. Data were grouped so t h a t areas o f t h e mainstem were o f s i m i l a r d is tance.

R ive r k i l ome te r o f t h e Rogue R i v e r B i g B u t t e Year 205-216 217-228 229-240 241-252 Creek

Appendix Table A-5. Data used t o assess f a c t o r s t h a t a f f e c t e d t h e d i s t r i b u t i o n and spawning t ime o f w i l d female sp r ing chinook salmon t h a t spawned i n t h e Rogue R iver , 1974-87. Data on spawning t ime are presented i n Appendix Table A-9.

Spawning Flow Water temperature Year d i s t r i bu t i ona Migra t ionU spawningc Incubat ionU Spawn i nge'

Percentage that spawned upstream of RK 245 among w i l d females that spawned upstream of RK 205. Mean flow ( c f s ) near McLeod during August. Mean f low ( c f s ) near McLeod during September-October. Mean maximum temperature ("C) near McLeod during October-January i n year i - 4 . Mean maximum tempertlture ( "C) near McLeod during September-October.

Appendix Table A-6. Number o f unmarked female chinook salmon counted weekly as spawned carcasses i n the Rogue River between Shady Cove and E l k Creek (RK 235-245), 1974-87. The area was not surveyed dur ing 1982-85. Week-of- year calendar i s i n APPENDIX D.

Week-of-year Year 3 8 3 9 40 4 1 42 43 4 4 4 5

Appendix Table A - 7 . Number o f unmarked female chinook salmon counted weekly as spawned carcasses i n the Rogue River between E l k Creek and Cole M. Rivers Hatchery (RK 245-252), 1974-87. Week-of -year calendar i s i n APPENDIX D.

Week-of-year Year 38 39 40 4 1 4 2 43 44 45 4 6

Appendix Table A-8. Number o f unmarked female chinook salmon counted weekly as spawned carcasses i n B i g Bu t te Creek (RK 0-2), 1974-87. The area was n o t surveyed du r ing 1982-85. Week-of-year calendar i s i n APPENDIX D.

Week-of -year Year 38 3 9 40 4 1 4 2 4 3 44 45 4 6

Appendix Table A-9. Est imated t ime o f spawning o f unmarked female s p r i n g chinook salmon i n t h e Rogue R ive r and i n B i g Bu t te Creek, 1974-87. The t ime o f spawning was no t es t imated f o r o the r areas because some spawners were f a l l chinook salmon. Day-of-year calendar i s i n APPENDIX D.

Year Mean day-o f -year 2 95% conf idence i n t e r v a l

RK 235-245 RK 245-252 B i g Bu t te Creek

Appendix Table A-10. Median date o f spawning o f female spring chinook salmon spawned annually a t Cole M. Rivers Hatchery, 1975-87. Data received from Michael Evenson, ODFW, Cole M. Rivers Hatchery, T r a i l , Oregon.

Year Date Year Date

APPENDIX B

Figures Showing Annual Re1 a t i onshi p Between Location o f Carcass Recovery and Date o f Tagging

L

I MAY I I JULY I I SEPTEMBER I

DATE OF TAGGING

DATE OF TAGGING

-

-

Appendix Figure B-1. Annual r e 1 a t ionship between 1 ocat ion where tagged carcasses were recovered and t h e date chinook salmon were tagged a t Gold Ray Dam, 1974-78.

I MAY I I JULY I I SEPTEMBER I

l m a 1978 j 1 . b 8 :

B a a l ' 2 b e l

a

* a a

l ! a a l

a a a a

J a a

a

a

a a 8 . a a a a

a a a

r = -0.53 • • • a a a

a

-

-

200 , I MAY I I JULY 1 I SEPTEMBER I

DATE OF TAGGING

Appendix Figure B-2. Annual re1 ationship between 1 ocation where tagged carcasses were recovered and the date chinook salmon were tagged at Gold Ray Dam, 1986-87.

APPENDIX C

Figures Showing Annual Re la t ionship Between Date o f Carcass Recovery and Date o f Tagging

DATE OF TAGGING

-

-

-

-

11/15

11/01 -

10/15 -

10/01 -

09/15 - I MAY I I JULY I SEPTEMBER I

1976

. l a

. a

# # a a . . l #

a : a * * ( a

l a * * * *

* * a • r = 0.70 a

DATE OF TAGGING

10/15 -

10/01 -

09/15 -

Appendix F i g u r e C-1 . Annual r e 1 a t i o n s h i p between t h e d a t e tagged carcasses were recovered and t h e d a t e chinook salmon were tagged a t Gold Ray Dam, 1974-78.

I MAY I I JULY I I SEPTEMBER I

r . 0 . 8 o " o o o .

0 8 : . a . . 0 .

P 8 08 l a s : # . 4. ! a : r .

0.

8 r 0 .

r = 0.55

-

-

-

DATE OF TAGGING

09/15 -

Appendix F i g u r e C - 2 . Annual r e 1 a t ionsh ip between t h e d a t e tagged carcasses were recovered and t h e d a t e chinook salmon were tagged a t Gold Ray Dam, 1986-87.

MAY I ' JULY 1 ' SEPTEMBER I

r = 0.42 -

APPENDIX D

Re1 a t i on between Gregori an day, day-of -yea r and week-of-year .

Gregorian day Day-of -yea r Week-of -yea r

1-7 January 8-14 January 15-21 January 22-28 January

29 January-4 February 5-11 February 12-18 February 19-25 February

26 February-4 March 5-11 March 12-18 March 19-25 March

26 March-1 Apri l 2-8 Apri l 9-15 Apri l 16-22 Apri l 23-29 Apri l

30 Apri 1 -6 May 7-13 May 14-20 May 21-27 May

28 May-3 June 4-10 June 11-17 June 18-24 June

25 June-1 J u l y 2-8 J u l y 9-15 J u l y 16-22 J u l y 23-29 J ~ l y

a Eight -day week d u r i n g leap yea r s .

Gregor ian day Day-of -year Week-of-year

J u l y - 5 August 2 August 19 August 26 August

27 August-2 September 3 -9 September 10-16 September 17-23 September 24-30 September

1 -7 October 8-14 October 15-21 October 22-28 October

29 October-4 November 5- 1 1 November 12-18 November 19-25 November

26 November-2 December 3 -9 December 10- 16 December 17-23 December 24-31 December

Eight-day week.