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The role of behavior in the interaction of underyearling coho and steelhead (Oncorhynchus kisutch and… Hartman, Gordon Frederick 1964

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THE R O L E OF B E H A V I O R OF U N D E R Y E A R L I N G  I N THE I N T E R A C T I O N  COHO AND  (ONCORHYNCHUS K I S U T C H AND  by  STEELHEAD  SALMO  GAIRDNERIl)  ^  GORDON F ; HARTMAN B'.A. , The U n i v e r s i t y  of British  Columbia,  1954  M.A.,  of British  Columbia,  1956  The U n i v e r s i t y  A T H E S I S S U B M I T T E D I N P A R T I A L F U L F I L M E N T OF THE R E Q U I R E M E N T S • DOCTOR OF  OF THE DEGREE  OF  PHILOSOPHY  in the DEPARTMENT OF ZOOLOGY  We a c c e p t t h i s t h e s i s a s c o n f o r m i n g t o t h e standard r e q u i r e d from c a n d i d a t e s f o rthe d e g r e e o f DOCTOR OF P H I L O S O P H Y  Members o f t h e D e p a r t m e n t o f Z o o l o g y The  University May,  of British 1964  Columbia  In the  r e q u i r e m e n t s f o r an  British  mission  for reference  for extensive  p u r p o s e s may  be  cation  of  written  Department  of  and  by  for  May  29,  agree for  that  of •  per-  scholarly  Department  shall  of  make i t f r e e l y  or  t h a t , c o p y i n g or  f i n a n c i a l gain  Columbia,  fulfilment  University  shall  I further  Head of my  Zoology  l?6k  Library  the  this thesis  permission,  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, Canada  Date  the  study,.  the  in partial  degree at  I t i s understood  this thesis  w i t h o u t my  that  c o p y i n g of  granted  representatives.  this thesis  advanced  Columbia, I agree  available  his  presenting  not  be  by publi-  allowed  - i i -  ABSTRACT  Two  similar  many c o a s t a l r i v e r s reveal  that  steelhead the In  are s i m i l a r  spring  pools,  t r o u t occupy  (1956)  stated that i n spring  resulting  from  hypothesis  both  depth  a n d summer  of  result  of interaction  which  of the species  and  inherently high  not  segregate  levels  i n streams  demands a r e d i f f e r e n t ,  competition  o f coho  this  and  steelhead  seasons  D i s t r i b u t i o n s , and  with  preferences  e n v i r o n m e n t s were  together  i s produced  and w i n t e r , t h e i n nature.  i's p r o b a b l y  the  by e c o l o g i c a l  and a c c e n t u a t e d  by dense  of aggressiveness. because  are lower  most  segregation  i n autumn  i n the streams  i n winter  are low.  when  o r d e p t h / v e l o c i t y and i n  occurred  numbers  coho  Nilsson  To t e s t  at different  similar  segregation  i s different.  and w i n t e r ,  a n d summer, t h e s e a s o n s when and l e a s t  However,  shown by coho and  be i n d i c a t i v e  aquarium  and p o o l s .  Spring  aggressiveness  as t h a t  and b e h a v i o r  s e a s o n s when t h e two s p e c i e s  of  streams.  i n h a b i t the pools.  i n the experimental  i n nature,  similarities  collections coho and  I n autumn  (such  cohabit  d e n s i t i e s are high,  e c o l o g i c a l demands.  cover,  riffles  i n spring  occurred  species  i n a stream  t h e two s p e c i e s  similar  riffles.  a n d s u m m e r ) may similar  Field  o f t h e two s p e c i e s  segregation  of light,  experimental of  Columbia.  the length o f these  the d i s t r i b u t i o n  compared  gradients  and s t e e l h e a d ,  and summer, when p o p u l a t i o n  are lower,  were  along  coho  of underyearling  distribution  numbers  trout  of British  the d i s t r i b u t i o n s  microhabitat  occupy  salmonids,  populations  The s p e c i e s  do  certain ecological  and i n h e r e n t  When t h e t w o s p e c i e s  were  levels together  -ii'i-  in  the  experimental  aggressive were  and  defended  aggressive riffles.  These  the  distribution  of  The  data  the  support  competition  the for  role  and  areas  i n pools  the  illustrate  riffle  but  pool  environment,  in riffles less  .but  inclined  differences i n behavior t r o u t and basic of  space.  coho  to  i n pools;  defend  probably  in natural 'riffles  contention  behavior  not  t r o u t were  of  Nilssdn  i n segregation  coho  space  in  account and  (1956)  produced  for  pools. and by  -iv.TABLE OF CONTENTS  .  p  a g  INTRODUCTION  .  1  PART  ....  3  I.  F I E L D STUDY  D E S C R I P T I O N OF STUDY A R E A  3  A. C h i l l i w a c k R i v e r  3  B. A l o u e t t e  9  River  .  C. S a l m o n R i v e r  ••'  M A T E R I A L S AND METHODS RESULTS A.  13  .  17  .. . Early 1.  19  Life  History  Longitudinal  o f Coho  distribution  2. M i c r o h a b i t a t s and t r o u t 3. S i z e  and Trout  . ..  i n streams  of underyearling  19 ...  coho 24  r e l a t i o n s h i p s of -fish  In the  Salmon R i v e r 4. PART  II.  Summary  EXPERIMENTAL  26  a n d comments  STUDY  26 •  '  M A T E R I A L S AND METHODS 1.  Holding  conditions  and f i s h  o f stream  3. D e s c r i p t i o n  of experimental  Experimental  5. S c o p e  31  aquarium environments  procedure  48  R e p l i c a t i o n of experiments  2. S e a s o n a l  changes  3. C o m p a r i s o n 4.  Description  5. A n a l y s i s  35  47  _ 1.  32  43  of results  RESULTS  31 31  2. D e s c r i p t i o n  4.  19  i ndistribution  of species  i n gradients  of agonistic behavior  of behavior  48 48 52 65 70  -V-  Page • RESULTS  -  continued 6.  Distribution  7. A g g r e s s i v e 8.  in riffle  behavior  and p o o l  in riffles  habitat and p o o l s  Summary o f r e s u l t s  74  . 77 85  DISCUSSION  87 A.  Behavior to  LITERATURE  ..  of Steelhead  their  B.  Interaction  C.  Comments  CITED  and Coho  i n  Relation  Ecology  87  o f Young S t e e l h e a d  on C o n c e p t s  and Coho  of Competition  91 94 97  vi  L I S T OF  -  FIGURES  Figure 1.  Page Lower F r a s e r v a l l e y area i n s o u t h w e s t e r n B r i t i s h Columbia showing A l o u e t t e , C h i l l i w a c k and S a l m o n R i v e r s y s t e m s  4  2.  Chilliwack River  5  3.  Upper C h i l l i w a c k R i v e r V-36  to  and  l o c a t i o n s of i n area  of  stations large  6  Chilliwack River  5.  C h i l l i w a c k R i v e r a t V-5.5 and V-6. Note c h a n n e l and u n s t a b l e g r a v e l b a r s A l o u e t t e R i v e r and l o c a t i o n s o f s t a t i o n s  7A.  B.  i n the  Alouette  River  a t A-7.  9.  Salmon R i v e r  showing  Salmon R i v e r  at  11. 12.  13.  14.  of  V-17.5  River  and  pool  at  gravel  7 braided 8 10  bottom  ,  Alouette  Riffle  Note  channel  8.  B.  region  A l o u e t t e R i v e r at A-12, channel with large boulders on b o t t o m and w i t h s t r e t c h e s c o n t a i n i n g l a r g e pools  modified  10A.  jams,  V-38  4.  6.  log  A-2  l o c a t i o n s of  and  •  i n meadow and  farm  11 land  .....  stations  S-9 areas  11  12 14 15  at  S-14  C o l l e c t i o n o f f i s h w i t h d e t o n a t i n g fuse.. (See small explosion l e f t foreground, upper photograph) D e n s i t y and d i s t r i b u t i o n o f y o u n g coho and steelhead i n the C h i l l i w a c k R i v e r . (Data c o m b i n e d f o r p e r i o d f r o m November 1959 to M a r c h 1962)  15  18  20  D e n s i t y and d i s t r i b u t i o n o f y o u n g coho and steelhead i n the South Alouette R i v e r . (Data c o m b i n e d November 1959 t o M a r c h 1962)  21  D e n s i t y and d i s t r i b u t i o n o f y o u n g t r o u t and coho i n the Salmon R i v e r . ( D a t a combined November 1959 t o M a r c h 1962)  23  -  v i i -  Figure 15.  16.  17.  18.  19.  20. 21.  22.  23.  Page D e n s i t i e s o f y o u n g coho and s t e e l h e a d i n a r e a s where c o v e r ( l o g jams) i s p r e s e n t compared t o areas where cover i s absent. Data from the C h i l l i w a c k R i v e r , N o v e m b e r 1 9 5 9 t o M a r c h , 1 9 6 2 .... D e n s i t i e s o f young t r o u t and coho o f stream h a b i t a t , r i f f l e , open pool, during s i x periods of the t h e S a l m o n R i v e r , November 1959  i n three types c h a n n e l and year. Data from t o M a r c h 1 9 6 2 ...  25  .27  S i z e r e l a t i o n s h i p s o f u n d e r y e a r l i n g t r o u t and coho i n the. S a l m o n R i v e r , Smoothed c u r v e s are based on m o v i n g a v e r a g e s o f t h r e e , d a t a b e f o r e s m o o t h i n g was p l o t t e d i n o n e mm l e n g t h i n t e r v a l s . '  28  L e n g t h f r e q u e n c i e s o f two o r more y e a r c l a s s e s o f t r o u t i n the. S a l m o n R i v e r . Data are lumped, October to February i n c l u s i v e , f o r three w i n t e r s .  29  T e m p e r a t u r e maxima and m i n i m a ( d a i l y ) i n t h e stream aquarium d u r i n g three seasons i n which t h e s t u d y was made ( s o l i d l i n e s ) . Breaks i n t h e l i n e i n d i c a t e t h a t no e x p e r i m e n t s w e r e i n progress. Dotted l i n e s represent temperature maxima and m i n i m a i n h o l d i n g t r o u g h s p l o t t e d f o r t w o w e e k s o r m o r e p r e v i o u s t o e x p e r i m e n t s ...  33  E x p e r i m e n t a l stream aquarium. Details d r i v e m e c h a n i s m are n o t shown  34  of  the  L a t e r a l and p l a n v i e w s o f c o n t r o l a r r a n g e m e n t and l i g h t , c o v e r , d e p t h and d e p t h and v e l o c i t y gradients. L i g h t and c o n t r o l c o n d i t i o n s appear s i m i l a r except f o r graded f i l t e r s used to produce l i g h t g r a d i e n t  '..  36  V e l o c i t y p r o f i l e i n h o r i z o n t a l and s a g g i t a l p l a n e s i n d e p t h g r a d i e n t . U p p e r f i g u r e shows v e l o c i t i e s 1 0 cm. a b o v e b o t t o m , e x c e p t i n s e c t i o n 1, r i g h t e n d , w h e r e p r o f i l e i s . d r a w n f o r p o s i t i o n 5 cm. a b o v e b o t t o m . Lower f i g u r e shows c o n d i t i o n s i n s a g g i t a l p l a n e (two c e n t e r readings averaged). Arrows i n d i c a t e d i r e c t i o n of c u r r e n t , d o t t e d l i n e s r e p r e s e n t screens  39  V e l o c i t y p r o f i l e i n d e p t h and v e l o c i t y g r a d i e n t . U p p e r f i g u r e s h o w s v e l o c i t i e s 10 cm. above bottom. L o w e r shows v e l o c i t i e s i n s a g g i t a l p l a n e (two c e n t e r r e a d i n g s a v e r a g e d ) . Arrows i n d i c a t e d i r e c t i o n of flow, dotted l i n e s represent screens  40  - v i i i Figure 24.  25.  26.  27.  28.  29.  30.  31.  Page H o r i z o n t a l (upper) and l a t e r a l v i e w s o f e x p e r i m e n t a l ' r i f f l e and p o o l e n v i r o n m e n t . H o r i z o n t a l arrow i n d i c a t e s d i r e c t i o n of c u r r e n t . V e r t i c a l arrow i n d i c a t e s water surface  42  D i s t r i b u t i o n s o f coho and s t e e l h e a d i n " c o n t r o l " and " c o v e r " g r a d i e n t s , d e s c r i b e d i n t e x t , d u r i n g three seasons. D o t s a n d c i r c l e s r e p r e s e n t mean number o f f i s h p e r s e c t i o n o v e r a one d a y p e r i o d (10-15 o b s e r v a t i o n s ) . Vertical lines indicate range. S e c t i o n 1 r e p r e s e n t s t h e upstream end o f the aquarium ,  49  D i s t r i b u t i o n s o f coho and s t e e l h e a d i n " l i g h t " , " d e p t h " , and " d e p t h and v e l o c i t y " g r a d i e n t s , as described i n t e x t , during three seasons. Circles and d o t s r e p r e s e n t mean number o f f i s h p e r s e c t i o n (10-15 o b s e r v a t i o n s ) . Vertical lines represent range. Section 1 represents the upstream end o f t h e aquarium ,  50  D i s t r i b u t i o n o f coho i n c o v e r g r a d i e n t d u r i n g three seasons. L o c a t i o n s o f 4 0 f i s h d u r i n g 10 combined o b s e r v a t i o n s are g i v e n . Groups o f dots r e p r e s e n t same f i s h o c c u p y i n g same l o c a t i o n r e p e a t e d l y , o r d i f f e r e n t f i s h , i n t h i s and succeeding figures of t h i s type. Points within the stone o u t l i n e s r e p r e s e n t f i s h under stones. D o t t e d l i n e s r e p r e s e n t s c r e e n s a t ends o f a q u a r i u m i n t h i s f i g u r e and s u c c e e d i n g figures of t h i s type  54  D i s t r i b u t i o n o f steelhead i n cover gradient during three seasons. L o c a t i o n s o f 40 f i s h d u r i n g 10 c o m b i n e d o b s e r v a t i o n s a r e g i v e n . P o i n t s w i t h i n t h e stone o u t l i n e s r e p r e s e n t f i s h under s t o n e s , ..  55  D i s t r i b u t i o n o f coho i n d e p t h g r a d i e n t d u r i n g three seasons. L o c a t i o n s o f 40 f i s h d u r i n g 10 combined o b s e r v a t i o n s are g i v e n . Rows o f p o i n t s at s e c t i o n b o u n d a r i e s r e p r e s e n t f i s h occupying p o s i t i o n s . a l o n g t h e e d g e s o f t h e d e p t h z o n e s ...  58  D i s t r i b u t i o n of steelhead i n depth gradient during three seasons. L o c a t i o n s o f 40 f i s h d u r i n g 1 0 c o m b i n e d o b s e r v a t i o n s a r e g i v e n . Rows of p o i n t s at section boundaries represent fish o c c u p y i n g p o s i t i o n s a l o n g .edges o f d e p t h z o n e s . .  59  D i s t r i b u t i o n o f coho, l a t e r a l view, i n depth gradient during three seasons. Locations of 40 f i s h i n 10 c o m b i n e d o b s e r v a t i o n s a r e g i v e n  60  ..  -ixFigure 32.  33.  34.  35A. B.  C. 36A.  B. 37.  38.  39.  Page D i s t r i b u t i o n of steelhead, l a t e r a l view, i n depth gradient during three seasons. Locations of 4 0 f i s h i n 10 c o m b i n e d o b s e r v a t i o n s a r e g i v e n . . . .  61  R e l a t i o n s h i p o f coho and s t e e l h e a d c o m b i n e d i n d e p t h g r a d i e n t d u r i n g summer c o n d i t i o n s . L o c a t i o n s o f 20 c o h o p l u s 20 s t e e l h e a d i n 1 0 combined o b s e r v a t i o n s are g i v e n  62  R e l a t i o n s h i p o f coho and s t e e l h e a d c o m b i n e d i n depth gradient during winter c o n d i t i o n s . L o c a t i o n s o f 20 c o h o p l u s 20 s t e e l h e a d i n 10 combined o b s e r v a t i o n s are g i v e n ,  63  Coho,  66  ca  10  months o l d , i n l a t e r a l  threat posture..  S t e e l h e a d , ca 8 months o l d , i n l a t e r a l posture (see f i s h on t h e l e f t ) . F i s h on t h e r i g h t i n f r o n t a l t h r e a t posture of low i n t e n s i t y Coho,  ca  2 months  old, in lateral.threat  posture  66 ..  66  Coho, ca 2 months o l d , i n f r o n t a l t h r e a t p o s t u r e of low i n t e n s i t y ( r i g h t ) . Coho, ca 2 months o l d , i n w i g wa.g p o s t u r e ( l e f t ) , ,  67  C o h o , c a 2 m o n t h s o l d , i n w i g wag l a t e r a l threat posture (right)  67  (left)  and  N i p p i n g i n t h e . p a i r o f f i s h on t h e l e f t . P i c t u r e taken a f r a c t i o n of a second before the f r o n t f i s h was n i p p e d . Second p a i r of f i s h (right side) i n c h a r a c t e r i s t i c l a t e r a l postures  69  Rate of o c c u r r e n c e of i n d i v i d u a l components i n t h e a g o n i s t i c b e h a v i o r o f y o u n g coho and steelhead. D a t a a r e b a s e d on c o m b i n e d o b s e r v a t i o n s of f i s h i n the f i v e experimental arrangements used. See t e x t f o r d e s c r i p t i o n of b e h a v i o r components  71  D i s t r i b u t i o n o f coho and s t e e l h e a d a t f o u r d i f f e r e n t d e n s i t i e s i n r i f f l e and p o o l environment (July). S o l i d dots represent the a v e r a g e number o f f i s h p e r s e c t i o n , s p e c i e s separate. C i r c l e s a n d lkro.ken l i n e s i n d i c a t e the a v e r a g e number o f f i s h p e r s e c t i o n , s p e c i e s mixed. Scale f o r the p o i n t s f o r s p e c i e s mixed i s h a l f t h a t f o r s p e c i e s s e p a r a t e ( s e e F i g . 24 f o r d e t a i l s o f r i f f l e and p o o l e n v i r o n m e n t )  75  -  X  -  Figure 40.  41.  42.  43.-  44A.  B. C.  45.  Page D i s t r i b u t i o n o f coho and s t e e l h e a d a t f o u r d i f f e r e n t d e n s i t i e s i n r i f f l e and p o o l environment (November). S o l i d dots represent the a v e r a g e number o f f i s h p e r s e c t i o n , species separate. C i r c l e s and b r o k e n l i n e s i n d i c a t e t h e a v e r a g e number p e r s e c t i o n , species mixed. Scale f o r the points f o r species mixed i s h a l f that f o r species s e p a r a t e ( s e e F i g . 24 f o r d e t a i l s o f r i f f l e pool environment)  76  R a t e o f a g g r e s s i v e b e h a v i o r i n r i f f l e and p o o l h a b i t a t s d u r i n g J u l y and November. Data b a s e d o n o b s e r v a t i o n s made w i t h s p e c i e s separate. C v C i n d i c a t e s coho a t t a c k i n g coho and S v S i n d i c a t e s s t e e l h e a d a t t a c k i n g steelhead. Coho o b s e r v e d 390 m i n u t e s i n J u l y and 340 m i n u t e s i n November, s t e e l h e a d o b s e r v e d 380 m i n u t e s i n e a c h p e r i o d  78  R a t e s o f a g g r e s s i v e b e h a v i o r i n r i f f l e and p o o l h a b i t a t d u r i n g J u l y and November. Data based on e x p e r i m e n t s i n w h i c h s p e c i e s were m i x e d i n e q u a l n u m b e r s a n d o b s e r v e d 270 m i n u t e s i n J u l y and 250 m i n u t e s i n November. Meaning of s y m b o l s as f o l l o w s : C v C - coho a t t a c k i n g coho, C v S - coho a t t a c k i n g s t e e l h e a d , S v S - steelhead attacking steelhead, S v C s t e e l h e a d a t t a c k i n g coho  79  R e l a t i o n , of r a t e of aggressive behavior, to density of f i s h . Coho and s t e e l h e a d c o m p a r e d i n r i f f l e a n d p o o l h a b i t a t s d u r i n g two s e a s o n s . E a c h d o t o r c i r c l e r e p r e s e n t s 10 m i n u t e s o f o b s e r v a t i o n i n one s e c t i o n o f t h e a q u a r i u m . ( D a t a o b t a i n e d w i t h s p e c i e s s e p a r a t e ) ,.,  81  C o h o , c a 10 m o n t h s o l d , i n w i g wag p o s t u r e . Fish at l e f t i s d i s p l a y i n g and b e g i n n i n g t o d r o p back toward f i s h at r i g h t  83  Both f i s h dropping together  83  downstream  and  coming  closer  C o h o a t l e f t s t i l l i n w i g wag p o s t u r e , i t s t a i l almost s t r i k i n g f i s h at r i g h t . At t h i s p o i n t t h e f i s h a t l e f t may w h e e l a n d n i p t h e s e c o n d f i s h o r s e c o n d f i s h may f l e e ,,,  83  S m a l l g r o u p o f 8 coho w i t h one d o m i n a n t (second f r o m r i g h t ) and s e v e n s u b o r d i n a t e s . Small fish o c c a s i o n a l l y a v o i d e d a t t a c k by r e m a i n i n g still a n d r e s t i n g d o w n among t h e s t o n e s , s e e f o r e g r o u n d .  84  - x i -  Figure 46.  Page D i r e c t i o n o f r e t r e a t o f coho and s t e e l h e a d following i n t r a s p e c i f i c aggressive contests ( b a s e d o n 2 4 8 c o n t e s t s ^ among s t e e l h e a d a n d 4 5 8 among c o h o ) '  '89  -xii-  L I S T OF Table I.  II.  III.  IV.  V.  VI.  TABLES  -  Page  Average l i g h t i n t e n s i t y (L<LUX) o v e r the l e n g t h of the o b s e r v a t i o n flume. Three r e a d i n g s , a c r o s s the t a n k , were averaged f o r each f i g u r e . R e a d i n g s w e r e t a k e n o n t h e b o t t o m w i t h no water i n the aquarium. S e c t i o n 1 i s at the upstream . end o f t h e t a n k 37 Dimensions gradient  of  stones  ( i n cm)  used i n  cover 38  Number and s p e c i e s o f f i s h u s e d i n e x p e r i m e n t s i n r i f f l e and p o o l e n v i r o n m e n t . In Series 1 c o h o (c) w e r e u s e d a l o n e * i n S e r i e s 2, steelhead (S) w e r e u s e d a l o n e and i n S e r i e s 3 t h e two s p e c i e s were combined Numbers o f c o h o (C) and s t e e l h e a d (S) i n u p p e r and l o w e r h a l v e s o f s e c t i o n s 4 and 5 i n t h e d e p t h g r a d i e n t i n e a r l y summer a n d w i n t e r (June and J a n u a r y )  46  ,.  57  A g g r e s s i v e c o n t e s t s p e r f i s h p e r 100 m i n u t e s d u r i n g J u n e and J a n u a r y 1 9 6 3 . S y m b o l s a r e as follows: C-coho,. S - s t e e l h e a d , C - C - c o h o a t t a c k i n g c o h o , C ' S - c o h o a t t a c k i n g s t e e l h e a d , S'»S-steelhead a t t a c k i n g s t e e l h e a d and S * C - s t e e l h e a d a t t a c k i n g coho  64  M i n u t e s o f o b s e r v a t i o n o f c o h o and s t e e l h e a d i n c o n t r o l and f o u r e x p e r i m e n t a l arrangements d u r i n g s p r i n g , , f a l l and w i n t e r  72  - x i i i -  ACKNOWL E DGME NT S  Many p e o p l e work. the  D r . W.S.  Hoar  investigation.  study  has been  has given  fully  B.C. G o v e r n m e n t .  and  support  given  supported  me d u r i n g  advice  T.G. N o r t h c o t e  not  have  present  of the Fish  possible without  D r . C.C. L i n d s e y  valuable C.A.  ..criticisms.  Gill  during  read  a l l stages  their  field  Fay  helped  the  time  and  H. N e a t e who g a v e  Finally wife  work  me i n t h e e a r l y  I wish  Helen  I wish help  the last  B i o l o g i s t and The w o r k  would  Dr. I . Met.  a n d made  the extensive  D r . P. L a r k i n several  help  g i v e n by  F i t . L t . J . Baehr,  D. H a r v e y , P. K o h l e r , R. K r e j s a ,  phase  stages  Petrie,  o f the study. of the f i e l d  t o express  My l a t e  work,  years.  good  cheer  at  brother  I appreciate  my g r a t i t u d e t o W.  and b r o u g h t  three  R.  a n d D. W i l k i e a l l h e l p e d i n  t o acknowledge t h e help  during  Fisheries  D r . P. D e h n e l ,  J . L o g a n , E. P e t r i e ,  o r some o t h e r  he g a v e .  Chief  interest.  o f t h e work.  D. U d y , P. W i c k e t t  the  t o h i m . The  a n d Game B r a n c h .  I appreciate  B. L i s t e r ,  M. T e r a g u c h i ,  throughout  a n d Game B r a n c h o f  Chief" F i s h e r i e s  the manuscript  K. C a l v e r t , J . G e e , G, H a l s e y , R. L e i g h t o n ,  grateful  by t h e F i s h  C o w a n , D r . J . A d a m s , D r . D. C h i t t y , and  of this  and s t i m u l a t i o n  b y R.G. M c M y n n , f o r m e r  Dr.  the course  I am a p p r e c i a t i v e o f t h e e n c o u r a g e m e n t  S.B. S m i t h ,  been  helped  I am p a r t i c u l a r l y  the  Biologist,  have  Caulfield  Courtenay.  and t h e p a t i e n c e  o f my  1. INTRODUCTION Two  similar  species  of salmonids  many o f t h e c o a s t a l s t r e a m s  of B r i t i s h  - coho  kisutch),and  salmon  qairdnerii) early are  life  (Qncorhvnchus  - resemble history.  potential  given  more f u l l y  i n different  and  down d u r i n g Nilsson  populations similar  populations  those  To i n t r o d u c e  segregation fall  (Salmo and  they  allied  t o compete  only  i n the spring  concepts  o f coho that  species, or species the f u l l  range  conditions of intense  or closely  competition  related  which  and t r o u t  allopatric  having of  their  intra-specific  i n sympatric  species  forces  each  at i t s " e c o l o g i c a l optimum" i . e . under  conditions to which  some c o m p e t i t i v e  valuable  He p o s t u l a t e s  interspecific  of similar  i t i s  and w i n t e r .  a n d e a r l y summer.  Intense  of  ecology i s  the problem,  f o rthe separation  p o t e n t i a l s under  the lengths  i s pronounced  (1956) has developed  of closely  competition.  concepts,  c o e x i s t along  e c o l o g i c a l demands u t i l i z e  ecological  species  that  an e x p l a n a t i o n  spring  fish  trout  microhabitats; their  i nthe text.  t o note  during  These  steelhead  of present  and s t e e l h e a d  sufficient  may p r o v i d e  Columbia.  i n morphology, behavior  On t h e b a s i s  coho  but occur  breaks  together in-  competitors.-*-  Young streams  each other  occur  i t i s best  advantage.  adapted  I t i s this  o r where i t has  tendency  of species to  ^ The m e a n i n g o f c o m p e t i t i o n , when u s e d i n t h i s p a p e r , i s , " T h e d e m a n d , a t t h e same t i m e , o f m o r e t h a n o n e o r g a n i s m f o r t h e same r e s o u r c e s o f t h e e n v i r o n m e n t i n e x c e s s o f i m m e d i a t e s u p p l y . " (Milne, 1961). T h e m e a n i n g o f n i c h e i s a s g i v e n i n De B a c h a n d Sundby (1963).  2. utilize during  only  their  rigorous  e c o l o g i c a l optima  in  spring  is  and e a r l y  to obtain  some d e t a i l The  second  occurs  be  trout  objectives data  and n a t u r e  coho  conditions  when r e q u i r e m e n t s  competition.  fall  study.  , ;  s  Lindroth  functions  t o give  situation  and " s p e c i e s B "  controlled  preferences,  similar.  and  i f . segregation  Essentially this  ( N i l s s o n , 1956 and 1963) under are segregated the third  "species  an a d v a n t a g e  will'  i n this interaction.  Kalle'berg  enters  at t h a t  objective  into  (1958)  and N i l s s o n  interspecific  I t i s n o t c l e a r however, what t y p e  mechanism  first  segregation.  are s i m i l a r ,  s h o w n how b e h a v i o r  The  of i n t e r s p e c i f i c  I f the species  (1955a),  winter.  outlining i n  a r e most  ideas  and  study  and t r o u t , and t o d e t e r m i n e  conditions.  (1963) have  to this  are s i m i l a r  i s t o compare, under p a r t i a l l y  testing Nilsson  (1956),  segregation  ask i f the  and coho  from the f i e l d  to ascertain the r o l e of behavior  Newman  one m i g h t  the environmental responses,  when t h e s e  controlled period  and p r e s e n t  o f young  involves  o f young  are three  objective  concept  summer b u t d i f f e r e n t d u r i n g  the period  conditions, behavior  of this  and b e h a v i o r  There  results i n  interspecific interaction.  On t h e b a s i s requirements  that  of  A" a n a d v a n t a g e i n another.  behavioral in.one  3. Part  I.  FIELD  STUDY D E S C R I P T I O N OF S T U D Y  Three r i v e r s western  British  Chilliwack,  i n the lower  C o l u m b i a were  Alouette  AREA  Fraser  studied  valley  of  south-  (see i n s e t s of the  and Salmon R i v e r s  i n Fig.l ) .  A. C h i l l i w a c k R i v e r . The Washington  Chilliwack River rises  and d r a i n s  •620 m ) , t h e n c e  north  i t flows  into  west  The. r i v e r rocky  channel  Large  areas  jams  the channel  absent  (Fig. 4).  is  of these  (Fig. 5).  lowermost region  channel  Several  Mean m o n t h l y  this  tributaries  and l a r g e  from Water Resources  data  from t h e Water Resources  (V-28 t o l o g jams a r e  (Slesse,  Foley,  stretch of the river.  fluctuates  considerably;  and much o f t h e b o t t o m  t r a v e l s across sand  flat  and g r a v e l .  The  terrain;  the  Much o f t h e  ( s e e V-5 t o V - 2 , F i g . 2 ) . drains  an a r e a  1958 t o 1962, i n A p p e n d i x  data  extensive l o g  i s one l o g j a m n e a r V-5.  and dyked  2  a t V-28 ( F i g . 2 ) ,  of the river  i s braided  Chilliwack River flows,  with  tributaries  enter  i s composed o f u n s t a b l e  The  are covered  large  of the river  i s modified  Figure  i n a stable  to the region  i s less stable  There  River.  a deep v a l l e y  stretches  b e l o w V-13 t h e c h a n n e l  unstable  bottom  bottom  and T a m i h i C r e e k s )  discharge  hence,  through  I n the middle  (elevation  s t u d i e d -and s t a t i o n l o c a t i o n s .  of the upper r i v e r  V-13),  The  the Fraser  from C h i l l i w a c k Lake  (Fig.3).  Chipmunk  runs  C h i l l i w a c k Lake  into  shows t h e p o r t i o n o f t h e r i v e r  i n t h e C a s c a d e Range i n  Papers  o f 1 , 2 5 0 Jcm^. I are based  128 and 1 3 1 , and on  on  unpublished  D i v i s i o n o f the Department o f  Fig.  1. L o w e r F r a s e r v a l l e y a r e a i n s o u t h w e s t e r n B r i t i s h C o l u m b i a s h o w i n g A l o u e t t e , C h i l l i w a c k and Salmon R i v e r s y s t e m s . ft  Fig.  2.  Chilliwack  River  and  locations  of  stations.  6.  Fig.3.  Upper C h i l l i w a c k R i v e r l a r g e l o g j a m s , V-36  in to  area of V-38.  7.  Fig.4,  C h i l l i w a c k River i n the region of V-17.5.  Fig.5.  C h i l l i w a c k R i v e r a t V-5.5 N o t e b r a i d e d c h a n n e l and gravel bars.  and V-6. unstable  9. Northern occur Over  Affairs  during  two p e r i o d s  and above  during  and N a t u r a l  periods  seasonal  River,  Alouette  portion  South  Lake,  most  I t drains  through  (Fig. 7A),  flat  i n the Chilliwack  A-9.  o r i g i n a t e s at t h e west end into  the Pitt  6 shows  ( A - 1 6 t o A-9) r u n s and s t r e t c h e s bottom  i n a channel  In this  region  absent  along  the f u l l  with  Alouette  (data  the  shallow large  an u n s t a b l e  stable i n  River  flows  drains  an a r e a  over  B.C. H y d r o  do n o t a c c u r a t e l y r e p r e s e n t  Several  small  prevent  the river  from  The  stream  Log jams a r e  o f 2 0 5 km^. 1962.  Appendix  Records f o r  t h e dam o n t h e o u t l e t o f  and Power A u t h o r i t y ) . the flow  I n combination  drying  modified  sections of  (Fig.8).  from 1958 t h r o u g h  volumes  tributaries  and  of the r i v e r .  spillage  from  Lower  a n d mud.  passes  rock  bed has been  (Fig. 7B).  g r a v e l , sand  length  and 1959 r e p r e s e n t Lake  a  i s relatively  the r i v e r  flooding  i s composed o f f i n e  shows mean m o n t h l y  a  F r o m A-9 t o b e l o w A-6 t h e r i v e r  bottom  The  down  strewn with  (A-3 t o A-0) l i e i n meadowland  Alouette  River,  s t a t i o n s along  the  Alouette  sharply  studied.  The s t r e a m  terrain  bottom.  west  w h i c h was  b i g pools  above  River  to prevent  1958  fluctuates  and r a n g e s  considerably  I  to January.  i n Appendix I I ,  Figure  upper r i v e r  through  areas  gravel  Alouette  of the r i v e r  boulders  and O c t o b e r  flows  days.  temperatures  of the Fraser,  The valley  monthly  River  The  tributary  Highest  changes, discharge  near V-13, are presented  B. A l o u e t t e  of  - May t o J u l y  o f one o r two  Mean m o n t h l y  Resources.  up, hence  with flows  These  i n the r i v e r . ground  seepage  are never  zero  as  Fig.6.  Alouette  River  and  locations  of  stations.  Fig.7A.  B.  A l o u e t t e R i v e r at A-12, channel with l a r g e b o u l d e r s on b o t t o m and w i t h stretches containing large pools, A l o u e t t e R i v e r at A-7, b o t t o m and m o d i f i e d  Note g r a v e l channel.  12  Fig.8.  Alouette  R i v e r a t A-2 i n m e a d o w and f a r m l a n d .  13. indicated 1962  was  i n Appendix obtained  unpublished These  monthly spill  the  true  flow  excess water  river  fauna.  C.  (Alouette  Salmon  100  of m.  Salmon  the  on  and  Alouette  n.ear  and  and  therefore  H i g h e s t , mean  January.  Periodic  L a k e .'.during  flowand  mean m o n t h l y  recorded  April  Division,  Haney  River.  December  I I I contains  River)  town of  Alouette  dam  to  P a p e r No.131  f l u c t u a t i o n s of  Salmon R i v e r British  Figure  shows t h e  heavy  damage t o  the  temperatures  and  A-9.  9  rises  i n low  Columbia,  at  wooded  an  l o c a t i o n of  farmland,  e l e v a t i o n of  s t a t i o n s along  north-  about the  River.  have  upper  stable  Fig.9).  The  the  river  The  overall  tributaries  channels  middle  surroundings  river  the  1960  Water Resources  the  during  Langley,  The and  from A p r i l  River The  east  of  at  r e s u l t s ' i n sharp  Appendix  near  occur  rains,  ranges  from the  were r e c o r d e d  discharges  of  Discharge  from Water Resources  information  data  represent  I.  (see  river S-19,  river bed  character  of  the  flow and  l i e i n small and  lies  S-10  and  lying  valleys S-18, flat  Below  sand  i s gentle, with  pools  to  i n almost  ( F i g . 10A).  m e a n d e r s t h r o u g h m e a d o w s i n a mud  S-6  channel.  much o f  the  i n w e l l wooded  areas  10B). The  monthly  to  the  gravel  c o n s i s t i n g of r i p p l e s  (Fig.  the  S-12  s e c t i o n of  i n a sand, and  of  flows  Salmon R i v e r (Appendix  drains  I, based  data), reveal  a peak r u n - o f f  During  large  winter  short  an on  area  of  km  .  Mean  Water Resources D i v i s i o n  between November  term  83  and  February.  f l u c t u a t i o n s i n discharge  occur,  Fig.9.  Salmon R i v e r  showing  locations  of  stations.  15.  A  B  Fig.lOA.  B.  Salmon R i v e r R i f f l e and at S-14.  at  pool  S-9. areas  16. e.g.  from  0.85  m^  on  Appendix ranges  to  8.32  m^  contains  mean m o n t h l y  (Salmon R i v e r )  recorded  at  habitat.  tributaries  three These  with  studied  habitats  range  gentle  flows,  Bottom  conditions  sand  gravel  to  stable  contain from  to  large  i n each gravel  on  January  25,  temperatures  1960. and  S-9.  rivers  rivers. and  23  IV  The of  January  or  a v a r i e t y of  types  small,  low  elevation  rapid  and  turbulent  stream vary boulders.  from  unstable  17. M A T E R I A L S AND  Young  coho  salmon  and  three  lower mainland rivers  River  ( F i g . 2), the Alouette  River  (Fig. 9),  about  once  Twelve  a month  permitted.  the  River  blasting  caps were  under  above seine;  "Prima Cord", used  l o g jams. net  the b l a s t  area  f o r each  approximate  velocities objects. crude on  were  observations  ,Each s t r i p w a s  67 m  seining  in  i n the l a r g e r r i v e r s .  In  a detonating fish  fuse,  by  and  electrical  among t h e l a r g e b o u l d e r s  s m a l l ) was  a standard  included  data sheet  number o f f i s h sampled.  from the r a t e  the  (Fig.ll).  and  a  sketch  collected  and  Temperatures  were  Stream  o f movement o f  floating  c o m p o s i t i o n were r e c o r d e d on  In addition,  supplemented  with  River.  distribution  distribution a series I n each  f t . ) long  of  data  a  based  diving  diving  census  the  o f f i s h were r e c o r d e d i n t h r e e  on t h e s t r e a m m a r g i n  (200  stream  into  searched  temperature recorders.  bottom  basis.  strips  collected  fish drifted  i n the C h i l l i w a c k  census  followed i f  the  and  number, b e h a v i o r and  1962.  ( F i g . l l ) and  calculated  were  visited  detonated i n the  constant  quantitative  standard  possible  Salmon  were  t o March,  in  Chilliwack  was  k e p t on  Turbidity  collections,  per r i v e r  always  area of stream bottom  taken.by Weksler  studied  explosive  (usually  station,  were  and t h e  p r o c e d u r e was  to collect  The  a set seine  Records, map  ( F i g . 6)  stations  were  and w h e r e v e r  C.I.L.  and  River  t o 16  Fish  trout  of B r i t i s h Columbia, the  collection  conditions  addition  steelhead  from November, 1959,  A routine  Salmon  METHODS  and  about  a t V-28 one  and  meter  V-30. wide.  t  Fig.11.  Collection  of f i s h  with  detonating  (See s m a l l e x p l o s i o n l e f t upper photograph)  fuse.  foreground,  19. R E S U L T S A.  Early 1.  Life  History  Longitudinal Highest  Chilliwack High  necessarily type  log  j a m s ) was  In  this  better  recorded  of habitat  shelter  stations  the  the r i v e r to fish.  V - 2 2 , V-28  and V - 1 0 ) ,  species the  general  the  period  coho were  from t h i s , fashion  and  trout  all  of which 7A).  bottom,  pattern  captured  the length  the Alouette  occurred  River,  at s t a t i o n s  are c h a r a c t e r i z e d B e l o w A-9  ( F i g . 7B  ( b e l o w V-10)  numbers  was  were (V-17.5,  where t h e  At most  During  were  and  stations,  early steelhead;  distributed i n a  river.  greatest  concentrations  A-9, A-12,  A-14  by  of heavy  a cover mud,  densities  both  as i n  downstream than  species of the  the  of  and coho  t h e same i n w i n t e r  further  at  numbers  of trout  (Fig. 12).  i n areas with  and F i g . 8 ) ,  of f i s h  (See F i g . 1 2 ) . I n  braided,  steelhead.  h o w e v e r , t h e two along  offered  l o g jams  of the r i v e r  from March t o September  In  (Fig.  half  (large  Chilliwack.  at comparable l o c a t i o n s  The r e l a t i v e  abundant than  and  numbers  of the Chilliwack  distribution  summer, y o u n g  similar  reason  However  of the  stable,  a n d t h e c h a n n e l was  lowest.  coho were more  aside  more  not  were r e c o r d e d  ( F i g . 1 2 ) , where  those  i n the lower  upper r i v e r .  of the upper part  b e d was  (Fig.12).  (V-29 t o V - 3 8 ) , were  numbers  For t h i s  than  unstable  were  highest  and coho i n t h e  of the r i v e r  of the entire  and V-30  downstream p o r t i o n s  b o t t o m was  i n F i g . 12,  where  absent, were h i g h e r Y-13  i n streams  o f young t r o u t  characteristic  region,  Trout  i n the upper reaches  representative  the  and  distribution  densities  occurred  densities  o f Coho  sand  were  and A-15,  o f coho (Fig.13),  boulders  or unstable  gravel  low (Fig. 13). During  I STEELHEAD D COHO  MAR  I—  SEPT  30  STATION NO  Fig.12.  D e n s i t y and d i s t r i b u t i o n Chilliwack River. (Data 1959 t o M a r c h 1 9 6 2 ) .  o f young combined •  coho and s t e e l h e a d i n t h e f o r p e r i o d f r o m November  21.  |  STEELHEAD  D  COHO  MAR I-SEPT 30 Qm  Q -  O O  O O  -P | l  IOO-  ILJL  -  IOO  -  50 O O O  2  or  I  2  a  2  i  |  OCT I - F E B  28  UJ  _)  LAJ  IOO-  rrr 14 15 16,  20  Fig.13.  STATION  KM  NO  D e n s i t y and d i s t r i b u t i o n o f young coho and s t e e l h e a d i n t h e S o u t h A l o u e t t e River. ( D a t a combined November 1959 to March 1962).  22. the  winter,  probably  density  due  to  periodically. were  at  In the  along  much o f  the  upper  upstream  the  10).  Much o f trees.  gravel  o r sand  were  lower  down t h e a t S-2  the  of  the  the  B e l o w S-8 and  S-3.  mud;  flow of  each  the  conditions  three  not  the  distribution  the  numbers  streams i n the  the  fry  Figure coho  -  river  coho  distributed  trout  14).  i n low more  and  (S-9  13  varied  together  pools  and  coho  mud  This  and  bottom  recorded  and  area  in i t s  of  covered  (Fig.  with unstable  trout in this coho were  portions  than  trout  the  riffles  composed of and  together  S-18)  gentle  overgrown  of  coho were  to  F i g . 14)..  b o t t o m was  the  types  comparable  of  and  level  of  at  over most of  area distributed  the  stream  a l l stations, the  length  14),  in habitat  and  scoured  trout  e a r l y summer y o u n g  into  differed  were  13,  S-19,  small  the  In  differences  (Fig.12,  to  occurred  (Fig.  of  sampling  young  numbers  A v a r i e t y of within  a low  steelhead.  were  Coho were more dense  species  stream  species  to  September 30,  numbers o f  s h o r e l i n e was  Salmon R i v e r  and  to  Salmon R i v e r ,  (S-12  ( F i g . 14).  however both of  relative  c h a r a c t e r i z e d by  fallen  freshets which  d e n s i t i e s of  tributary,  was  reduced  river.  part  river  was  p e r i o d March 1  s t a t i o n s , both  Highest in  species  f u r t h e r downstream than  although  different  both  violent winter  distributed  shows t h a t ,  of  of  p h y s i c a l h a b i t a t were  rivers.  Furthermore  considerably  between  same i n a l l r i v e r s .  and  sampling  patterns Trout  numbers  stable  and and  the  i n each coho  two of  size, the In  cohabited  occurred  environments  s p i t e of  the  and Methods such  exhibited  three  together  near the  bottom  streams.  species the  studied  rivers  lower in  sections  highest  head-waters  or  23. | Q  APR  M50  TROUT COHO  I - OCT  31  IOCH  2  z z  o r< >  UI  IOCH  Fig.14.  D e n s i t y and d i s t r i b u t i o n o f young t r o u t and coho i n t h e Salmon R i v e r . ( D a t a c o m b i n e d November 1959 t o March 1962).  24. head-water 2.  lakes.  Micro-habitats of underyearlinq In  trout the  Alouette  River  Recently  at  three  most and of  three  During  occurred winter  absent were  found  •In stones  those  fish  only  cases  where  shore.  fall,  Figure  under  where  young  was  coho were  their  found  distribution  a wider  The s p e c i e s  d i s t i n g u i s h e d i n Figur.e  d i d not  hand were  was  same a t a l l s e a s o n s .  absent. was .  among t h e l a r g e  steelhead  microhabitats  areas,  cover  where l o g cover  as much as 8 m f r o m  the Chilliwack river.  banks  reduction i n  among t h e b o u l d e r s  in  fall  the rocky  t o l o g jam  collected  t o occupy  By l a t e  o r among t h e b o u l d e r s .  Young t r o u t on t h e o t h e r  able  The  15 shows t h e  l o g cover  areas  bays  crevices  overhanging  occupied  seasonal  heavy  utilizing  at the stream margin,  from  and e a r l y f a l l .  A pronounced  i n areas  and s m a l l  l o g jams o r under  i n late  i n small  and l a r g e b o u l d e r s .  and coho i n r e l a t i o n  seasons.  seasons.  i n the Chilliwack  riffles,  and t h e l o g jams.  of steelhead  density  far  Steelhead,  summer  In  o r n o t changes i n  shallow water  o f l o g jams  during  the stream margin  during  shallow  l o c a t e d under  boulders.  density  small  portions  changed  coho were  at d i f f e r e n t and coho  coho and  of microhabitat.  whether  of microhabitat:  the stream margin,  distribution  occurred  emerged t r o u t  types  about t h e i n s h o r e  changes i n choice  i t was n o t c l e a r  of microhabitat  occupied  and t r o u t  t h e C h i l l i w a c k and Salmon R i v e r s , young  exhibited seasonal  choice  coho  variety  extend  seen and  shore.  The  of microhabitats•  composition  i n t h e two  1 5 was a p p r o x i m a t e l y  the  25,  COVER PRESENT  FISH  Fig.  15.  ABSENT  PER  lOO M  2  D e n s i t i e s o f young coho and s t e e l h e a d i n a r e a s where c o v e r ( l o g jams) i s p r e s e n t compared t o a r e a s where c o v e r i s a b s e n t . D a t a f r o m t h e C h i l l i w a c k R i v e r , November 1959 t o M a r c h 1 9 6 2 .  26. • In  the  Salmon R i v e r r e c e n t l y emerged  became. s e g r e g a t e d , first  two  riffles  months  and  The  i n the  June,  16).  In  fish the  degree  January  and  February  3.  coho  time,  17).  This  size  autumn u n t i l ,  Virtually June,  at  years  separated length were  of  Summary Field  along  the  as  data  lengths  in  different  in  microhabitat  of  i n the  10  the out  fish  were  reduced.  By  same  pattern  this  and  during  in  July  late alike  i n the  plus"  summer (Fig.17).  i n May  o f , t r o u t ( F i g . 18)  ( F i g . 19).  first  difference in  remained  "one-year  o r more  the  Salmon R i v e r  Trout  a l l trout  River  r a n g e s were  the  samples  Salmon  t r o u t i n June  size of  and  of  decreased  months.  year  riffles.  months  March, while  Because  winter,  one  and  fish  discrepancy  p l o t s of  coho  i n the  first  the  pools  period  t r o u t e x h i b i t e d the  l a r g e r than  Winter  in  (Fig. 16),  underyearling  designated  lowest  was  the  highest  this  the  emerge i n l a t e  a b o u t 14  frequency  4.  by  o r more. into  and  through  and  a l l coho m i g r a t e d age  In  trout  during  w i n t e r , when numbers o f  distribution  coho were  and  h a b i t a t s and  August. pools  emerged i n e a r l y June.  (Fig.  two  channel  S i z e . r e l a t i o n s h i p sof  hatching  and  and  d e n s i t y was  of h a b i t a t segregation  Coho b e g a n t o trout  open  i n the  fall  the  of m i c r o h a b i t a t  Trout  decreased  lowest,  to microhabitat,  J u l y and  were h i g h e s t  d e n s i t y of  (Fig.  ( F i g . 16).  lower  throughout Mayi densities  with regard  coho  fish  and  river  could  be  using  F i s h over  85  mm  age.  comments show t h a t the  t r o u t and  three  microhabitats  streams.  w i t h i n the  distribution  are  coho o c c u r They  streams.  most d i s t i n c t  are  together however  The  found  differences  i n the  small  27  300 200  H  COHO  •  TROUT  lOO MAY-JUNE  200 IOOJULY-AUG  IOOSEPT -  OCT  lOO NOV - DEC  50  JAN-FEB  50  MAR LU  _i  z  u_  —  —  O  —J  -  Z <  -APRIL  _1  o o  CL  U 16.  D e n s i t i e s o f young t r o u t and coho i n three types o f stream h a b i t a t , r i f f l e , open c h a n n e l and p o o l , d u r i n g s i x p e r i o d s of t h e year. Data from t h e Salmon R i v e r , November 1959 t o . M a r c h 1 9 6 2 .  28  1961 -62  TROUT COHO  60  90 FORK  Fig.17.  30  L E N G T H  (MM)  Size relationships of underyearling trout and coho i n t h e S a l m o n R i v e r . Smoothed curves a r e b a s e d on moving a v e r a g e s o f t h r e e , d a t a b e f o r e s m o o t h i n g was p l o t t e d i n o n e mm l e n g t h i n t e r v a l s .  29.  3 0 -  iP o2  O O  10-  O  •* i  o o  in  O i  O O I  O i  i  FORK LENGTH (MM)  Fig.18.  L e n g t h f r e q u e n c i e s o f two o r more.year c l a s s e s o f trout i n t h e Salmon R i v e r . Data are lumped, October t o February, i n c l u s i v e , f o r three winters.  30. stream, in  t h e Salmon R i v e r , where  riffles  occur  and p o o l s  together This  not  at another,  concepts and  may  stream into  However,  For t h i s  behavior of  part  reason fish  fish  o f t h e two  segregated  a t one  where  degree,  paper  Field  season  Nilsson's  are d i f f i c u l t controlled  the i n v e s t i g a t i o n  of comparing  species.  experimental'data.  be  c o u l d be  of t h i s  and t h e methods  occurs  situation  c o n d i t i o n s cannot  the second  facilities  segregation  a good  t h e l a b o r a t o r y where  aquarium;  light  where  be t e s t e d .  habitat.  are  i n winter.  provides  environmental  species  i n s p r i n g and summer, b u t , t o a l a r g e  i n pools case,  t h e two  to  (1956)-  observe  i n the natural was  studied i n a describes the  brought stream experimental  the d i s t r i b u t i o n  results  but  are d i s c u s s e d  and i n the  31. Part I I .  EXPERIMENTAL  STUDY  M A T E R I A L S AND 1.  Holding conditions The  1962  and  stream near  River  near  to  used  F e b r u a r y 20,  1962.  June  9 to October  several  seined  in  9,  intervals  t r o u g h s , 40 black  were  11  1963  were  were  October at  were and  Big  between A p r i l  t o 23,  1963.  25,  of f i s h ,  nets.  are  long.  15  and  1962  and  22,  October  i n work  1963.  Size at  given i n Appendix  V.  The  and i l l u m i n a t e d  i n painted  t r o u g h s were with  9,  from  measured  i n running water cm  19  Trout used  w e r e o b t a i n e d May  220  Qualicum seine  c a p t u r e d between October  held  a  o f o b s e r v a t i o n s (November 1,  the work,  chambers  from  River,  captured with  l e n g t h s of samples  wide  plastic  series  during  fish  cm  A l l fish  April  mean f o r k  All  steelhead  i n experiments  were  and  were o b t a i n e d from L i t t l e  Comox; t h e  1963)  1963  range  salmon  first  Coho u s e d  between  i n the Puntledge Park Hatchery  Parksville. i n the  conducted  Columbia.  coho  small  Fish  1963  British The  fish  e x p e r i m e n t a l s t u d y was  December  Courtenay,  and  METHODS  plywood housed  fluorescent  lights. Fish a 12  h r day  winter reduced  used  length  i n spring  (see Appendices  e x p e r i m e n t s were h e l d to 8 hr  from  increased  the C i t y during  of Courtenay and  VI  e x p e r i m e n t s were h e l d and  V I I ; those used  h r day  in  - subsequently  VIII).  i n holding  spring  fall  a t a 12  (see Appendix  Water used came  and  troughs  and  mains.  Water  early  stream  aquarium  temperature  summer, d e c l i n e d  gradually  at :  32. during  autumn and d r o p p e d  Stream  aquarium  in  the text.  (Fig.19) the  and  occurred  mixture the  (ca.  remained 2.  section  2 m high  supported  windows  the  axial  f e d once  6%  pablum  This  food  and f e d i n  d a i l y and  to represent  of the unit  (Fig.20).  short  a r e 6.3 m  The o b s e r v a t i o n  i s made o f 1" ( 2 . 5 cm)  ( 5 . 1 x 0.6 cm) a n g l e  a strong,  iron  glass.  frame  flume  lined  plywood (Fig.20).  Construction of  non-toxic r u s t - r e s i s t a n t  p o r t i o n o f t h e a q u a r i u m was t h e r e f o r e steel  a  deep.  a r e o f 5 / 8 " ( 1 . 6 cm) p l a t e  with  made o f  1 / 8 " ( 0 . 3 cm)  fiber-  plastic.  Current  i n the stream  desired velocity  pipes.  Dimensions  of t h e aquarium  reinforced  Water l e v e l  yeast,  aquarium  a n d .7 m  ( 0 . 3 cm) w e l d e d m i l d  glass  duct  stream.  2 1 % by weight  f o r storage  F i s h were  a n d 1.2 m w i d e  This  forced  the study.  f l o w pump r e q u i r e d  material.  frozen  a q u a r i u m was d e s i g n e d  i n a 2" x ^ "  The  the  scrapings.  12 m wide  Most  fed a diet  f o r 300 g r . o f f o o d ) .  a paste,  throughout  of a small  5 m long,  1/8"  into  stream  peak  water main  s a l m o n , 8% b r e w e r ' s  D e s c r i p t i o n of stream The  long,  were  one t e a s p o o n f u l  healthy  be r e f e r r e d t o l a t e r  supply.  canned  of frozen  (Fig.19),  and t w o - d a y • t e m p e r a t u r e  i n the troughs  was g r o u n d  form  will  when a b r e a k i n t h e c i t y  65% drained  salt  i n Fig.19  The s h a r p r i s e  Fish  is  temperature  u s e o f an a l t e r n a t e  liver,  t o 5°C o r l e s s i n w i n t e r  with  was a d j u s t e d  could  a v a r i a b l e speed with  W a t e r was c i r c u l a t e d  at t h e bottom  aquarium  an i n l e t from  of the unit,  hose  be m a i n t a i n e d  drive  at  mechanism.  and a s e r i e s o f d r a i n  t h e pumps a l o n g  the tapered  up a t t h e e n d o p p o s i t e  t h e mo-for  33.  C  S P R I N G  a  S U M M E R  , j n  -i 7  r  1  14 MAY  21  1  28  1  4  1  1  II  18 JUNE  1  25  1  T—  2  9 JULY  20-  IODAILY  FALL  — M AXIMUM—J^JJJJUJ^  — i —  8  Fi.g.19.  15 SEPT  22  29  6  OCT  — ^ "—MINIMUM HOLDING TROUGH  STREAM AQUARIUM  Temperature maxima a n dminima ( d a i l y ) i n t h e stream aquarium during three seasons i n which t h e s t u d y w a s made ( s o l i d l i n e s ) . Breaks i n the l i n e i n d i c a t e t h a t no e x p e r i m e n t s were i n progress. Dotted,lines represent temperature maxima a n dminima i n h o l d i n g t r o u g h s p l o t t e d f o r two weeks o r more p r e v i o u s t o e x p e r i m e n t s .  aq Experimental stream * « h  a  n  i  s  m  u a r l U a r e  ™l n  o  t  D e t a i l s of the hown. !  +  s  35. and  along  the observation The  fluorescent  flume  a p p a r a t u s was  lights  running  back  lighted  t o t h e pump. from  the f u l l  overhead  length  by  of the  parallel  observation  flume. An o b s e r v a t i o n paralleled in  each  the p l a s t i c  the  darkened  side  gallery  of black  of the tank.  Adjustable  facing, the aquarium  galleries,  without  permitted  control and  i n four  in a riffle-pool  of "these  of f i s h  different  environment.  arrangements  observation  slits from  fish.  environments  and d i s t r i b u t i o n  environment,  sheeting  horizontal  d i s t u r b i n g the  3. D e s c r i p t i o n o f e x p e r i m e n t a l Behavior  polyethylene  The  were  compared i n a  environmental  gradients  following i s a description  a n d some o f t h e c o n d i t i o n s  associated  with  them. Figure control  21  and f o u r  shows  lateral  gradients.  depth  ( 2 8 t o 29 c m ) , b o t t o m  (22  t o 24  cm/sec)  the  length  series  and l i g h t i n g  paint.  9 sheets Light  "photovolt" light  model  depth The  (Fig.  intensity  intensity  condition,  21c).  were  514.M  ( F i g . 2 1 b ) was  cover  with  photometer.  gradient  S t o n e s were  The  first  (Fig.21a)  velocity  uniform  along  was  Table  the observation were  produced with s h e e t was  t h e same  above  black  measured w i t h I shows flume.  the  small  a  average  Bottom  as i n t h e  consisted of five  elevated  a  clear,' the  p r o g r e s s i v e l y more  i n the gradient  and v e l o c i t y  of  flume.  coated  ( l u x ) along  views  (3 t o 6 cm),  c o n d i t i o n s were  of the observation gradient  gravel  o f 10 p l e x i g l a s s s h e e t s .  remaining  and p l a n  I n the c o n t r o l s i t u a t i o n  the  The.light  aspects  groups  control. of  depressions  stones i n the  36.  i  W A T E R  1  SURFACE  CURRENT IrXRECTION  2  d. C O N T R O L  -  •DARK-  - •  BRIGHT  •  b. L I G H T  1 O  o o°  O O  0 o  a  0  o  * or o  o  o  •  o «  •  C.COVER  d. D E P T H 2  IS  *  — 4  3 SECTION  Fig.21.  e. D E P T H + VELOCITY  L a t e r a l and p l a n v i e w s o f c o n t r o l a r r a n g e ment and l i g h t , c o v e r , d e p t h and d e p t h and velocity gradients. L i g h t and c o n t r o l conditions appear s i m i l a r except f o r graded f i l t e r s used t o produce l i g h t gradient.  Table  1.  Average l i g h t i n t e n s i t y (Lux) over t h e l e n g t h of the observation flume. Three r e a d i n g s , a c r o s s t h e t a n k , were a v e r a g e d f o r each f i g u r e . R e a d i n g s were t a k e n o n t h e b o t t o m w i t h no w a t e r i n t h e a q u a r i u m . S e c t i o n 1 i s a t t h e u p s t r e a m e n d o f .".the t a n k .  Meters 4.75 2.60  4.25 10.8  3.75 23.8  3.25 48.6  from Upstream 2.75 85.3  2.25 157.7  End o f 1.75 189.0  Tank 1.25 201.9  .75 375.8  .25 281.0  (Lux)  Table  I I . D i m e n s i o n s o f s t o n e s ( i n cm) used i n cover g r a d i e n t .  S 5  E  C 4  T  I  O  N  3  2  1  Range i n : Length  22-30  15-17  13-15  10-14  Width  18-24  12-14  10-11  7-8  5-6  4-6  4-7  2-4  . 2-5  2-4  Thickness  7-12  1.2- :  2  z i  i—  .6-:  20  20  5  .5Q. UI Q  0--  "I  20  '  1  0  1  20  WATER  Fig.22.  '  1  1  O  20  VELOCITY —  CM  '  1  1—  O PER  20  SEC  V e l o c i t y p r o f i l e i n h o r i z o n t a l and s a g g i t a l p l a n e s i n depth gradient. U p p e r f i g u r e s h o w s v e l o c i t i e s 10 cm a b o v e b o t t o m , e x c e p t i n S e c t i o n 1, r i g h t e n d , w h e r e p r o f i l e i s d r a w n f o r p o s i t i o n 5 cm a b o v e b o t t o m . L o w e r f i g u r e s h o w s c o n d i t i o n s i n s a g g i t a l plane (two center r e a d i n g s average). Arrows indicate d i r e c t i o n of current, dotted l i n e s represent screens,  B GO vO  1.2-,-  2 z  D  - 1 20  '  1 1  •  .5I rQ. UJ Q  O20  1  0 20  Fig.23.  (D  N  O 2i 0  1  i  _ 20  — • — l  C)  20  -. 20  O WATER  r-  i  <J  t  20 V E L O C I T Y — CM  T  20  •  1 20  PER  '  0 20  0  11 • O 20  1  SEC  V e l o c i t y p r o f i l e i n depth and v e l o c i t y g r a d i e n t . Upper f i g u r e s h o w s v e l o c i t i e s 10 cm a b o v e b o t t o m . Lower shows v e l o c i t y i n s a g g i t a l plane (two c e n t e r r e a d i n g s averaged), Arrows i n d i c a t e d i r e c t i o n o f flow,' d o t t e d l i n e s r e p r e s e n t screens.  ^  B  4^ o  41. gravel of  so  that  each had  stones i n each To  were  section  produce  the  kept  between  fish  the  above  bottom  covered with  was  Illumination floor  somewhat  floor  along the  and  sagittal  bottom  covered with  intensity  slightly  on  Figure arrengement  patterns  length  which Pool  the  the  the r i f f l e  current  upper  1,  circulates  upstream  along the bottom  seasonal  changes  cm/sec.  i n Sections  i n the  In  2,  cm/sec  i n the  by  means to  flume w i t h o u t  profiles  i n the  of the  in The  control.  false  floor  3  and  pool  cm  complex  of water  l o w e r 10 at 4  and  5,  along the  aquarium  environment. flow  below:  30  20  Temperature  where  not p o s s i b l e  to exhibit  i n Section  20  end  The  source.  produced  used  that  downstream lend.  briefly  and  was  end  light  I t was  upstream  so  control.  shown i n F i g . 23.  are d e s c r i b e d  surface  steps  of water  i n the  of v e l o c i t y  at about  at the  ( F i g . 21d).  of the observation  downstream  sec  plywood  ( F i g . 22).  to the  same g r a v e l  24 r e p r e s e n t s  Riffles  flow  size  i n Table I I .  of the  upstream  gradient  p l a n e s are  than the  caused  closer  Details  the r a i s e d  higher  edges  used  i n the  ( F i g . 21d).  depth or width.  was  higher  The  sheets of  3 and 4  even  same g r a v e l  elevated  horixontal  Light  the  slightly  false  1,. 2,  an  it.  as g i v e n  four  trailing  allowed  depth + v e l o c i t y  velocity  altering  and  under  constant at a l l depths  p a n e l s were  a sloping  vary  near  was  The  This  cavity  depth gradient  them, but  were  was  cm  varied  leading  velocities  of  to 6  arranged step-wise i n sections  Screens  the  a 4  to  to 5  current  12  flows  cm'current  cm/sec.  current  28  t o 30  cm/  bottom.  ( F i g . 19)  temperature of the water  was  governed  supply,  by  Fig.24.  H o r i z o n t a l ( u p p e r ) and l a t e r a l v i e w s o f e x p e r i m e n t a l r i f f l e and p o o l e n v i r o n m e n t . H o r i z o n t a l arrow i n d i c a t e s d i r e c t i o n of current. V e r t i c a l arrow i n d i c a t e s water surface.  43. conditions  w i t h i n the  b u i l d i n g and  Tank t e m p e r a t u r e  could  water.  be  water the  I t could and  hence  aquarium.  During  the  raised  allowing  of  new  a i r temperature  freshets the  the  November 1963,  9,  could  not  temperature  temperature would 10  and  be  11,  1962  and  J a n u a r y 8,  those  of the holding  aquarium  I f i t were 5  10,  If  such  and 12  low  6,  and  16°C  g e n e r a l l y warmer t h a n t h a t  a n d was  the  holding  ( F i g . 19).  i n the  stream  autumn, t e m p e r a t u r e s trough temperatures Figure  fluctuated  and  13,  ranged  stream tank  generally  from  and  summer  10°  to  i n the holding  stream  They  but  aquarium  ponds.  followed  9.4°  t o 14,6°.C.  temperatures  corresponded to those  of  higher.  Experimental procedure length  was  i n a l l experiments.  necessary  somewhat  spring  f l u c t u a t e d from  daily.  t r o u g h s but were  Day  that  and  During the  aquarium  i n the  shows t h a t  seasonally  holding 4.  19  deviated  troughs e a r l y i n the winter  water  with  and  F i g . 19).  experiments,  hr)  during  9,  contr.a;!..  aquarium.  (see October  them l a t e r  the  high  new i n  full  s o u r c e became t u r b i d  approximated  In  of  already  however p r o v i d e  would r i s e .  Temperatures w i t h i n the from  new  input  that  run i n t o the  fall  pump.  a d d i n g more  the p r o p e l l e r to heat d i d not  from the  c u t t i n g the  i n t h e b u i l d i n g was  aquarium  aquarium  by  f r e s h e t , the water water  input  l o w e r e d by  slightly  These measures  periods  consequently  u s u a l l y be  energy  m a i n t a i n e d a t 12 This  p h o t o p e r i o d was  of the holding  troughs during  however  a 12  a 2 hr period  of  t o use  adjustment  hr  hr  day  (06.00 t o not  consistent  the winter.  i n order to give  a f t e r the l i g h t s  18.00  came o n  It  was  the  fish  since  the  44.  subsequent  10 h r o b s e r v a t i o n p e r i o d was n e c e s s a r y  adequate r e c o r d s In as  i n still  following  raised  period.  water  During  betwe'en 2 0 . 0 0  t o 23 cm/sec  the f i r s t  day  o f a l l 40 f i s h  positions  Behavior observations revealed of  following letters,  i s a list details  N - nip,  -  L  In  this  light  and  and cover  i n each  During  section  the  1 2 t o 16 t i m e s  i n a series  second on  coded  A p r e l i m i n a r y study  so t h a t  a sequence o f  and t h e i r  be d e s c r i b e d  - w i g wag  components  and q u a n t i f i e d .  F - frontal  C •- c h a s e , WW  o f 10 m i n  comparable  elements  of behavior w i l l  The  code  later:-  display, display,  IM - i n t e n t i o n  movement and  flight. A protocol  Fish  A t 08.00 h r  a t 14 c m / s e c  intervals.  approximately  of behavior  TN - t h r e a t n i p ,  were  bottom.  These were  display,  40 f i s h  of fish  the l e n g t h of the tank.  behavior.  - lateral  Fl  started  observed  and a d j u s t e d  and 22.00 h r .  were p l o t t e d  was r e c o r d e d  c o u l d be r e c o r d e d  L  experiment,  t h a t t h e two s p e c i e s e x h i b i t e d  agonistic  events  along  f e d and  started  i n control,  o r one h o u r  of the stream  was  day numbers  at half  maps  Current I n each  were r e c o r d e d  outline  were h a n d l e d ,  d a y , t h e c u r r e n t was  i n two s t e p s  gradient.  and b e h a v i o r .  fish  as p o s s i b l e .  t h e same t i m e  placed the  a l l experiments  consistently  over  on d i s t r i b u t i o n  to obtain  "A"  + N  series  f o r a b e h a v i o r a l sequence Fish  "B"  L + WW  of events  fish  "A"  ;  N  ?  "A" d i s p l a y s  i s as  follows:  "B" —  F l  «-  i n lateral  posture  45.  than  nips  "B".  a w i g wag  Fish  display.  arrow under  The  8 t o 10  food  was  tank where the  brine  several  "A"  nips  fed twice  placed  during  thus  evoking  a r r a n g e m e n t was  Table  Coho  and t h e n  and s t e e l h e a d  numbers  followed  i n the aquarium  current  was  velocity an  by 09.00 h r .  than  studied  series of f i s h  of d i s t r i b u t i o n  each was  end o f t h e  fish  i n the  that  used w i t h the  used  was  succeeding  riffle-  i n two  series.  and t h e t i m e  experiments. placed  The  stepwise  i n  still  f o l l o w i n g day t h e  to the desired day, u n t i l  added a t 08.00 h r .  and b e h a v i o r  Many o f  period.  i n a third  20.00 h r .  were  ofi c e .  separately  series of  a d d i t i o n a l l o t of f i s h  recordings  i n studying  the three  On  a block  a prolonged  different  s t a r t e d and i n c r e a s e d  aquarium,  i n the current f o r  of f i s h  at about  The  o f 20 t o 6 0 m i n .  and s p e c i e s  each  flees.  i n the upstream  over  were  then e x h i b i t s  flight.  into  i n combination  during  To b e g i n , water  feeding  slightly  of  circulating  followed  observed  I I I gives  schedule  a n d "B"  frozen  a period  kept  posture  i n the stream  shrimp  shrimp r e l e a s e d  gradients.  again  above t h e s c r e e n  i t melted  hours,  series  daily  cc o f b r i n e  The p r o c e d u r e pool  "B"  " F l " indicates the direction  Fish, given  "B" d i s p l a y s l a t e r a l  were  the fourth,  Feeding  and  as p r e v i o u s l y  described. Experiments were  conducted  fish. the of  i n July  Experiments  spring, fall gradient  on f i s h  i n the r i f f l e - p o o l  and November,  1963, w i t h  i n t h e c o n t r o l and g r a d i e n t s  and w i n t e r .  experiments.  Appendices  arrangement underyearling were  done i n  VI to V I I I give  details  46. Table  I I I . Number and s p e c i e s o f f i s h u s e d i n i n r i f f l e and p o o l e n v i r o n m e n t . In coho (C) w e r e u s e d a l o n e , i n s e r i e s (S) were u s e d a l o n e and i n s e r i e s 3 s p e c i e s were combined.  Series No. C First  Day  1  of  S  20  Series  2  experiments series 1 2, s t e e l h e a d t h e two  Series  No. C  of S  No. C  of S  -  20  10  10  S e c o n d Day  40  -  -  40  20  20  Third  60  -  -  60  30  30  80  -  - . 80  40  40  Fourth  Day Day  3  47. 5.  Scope  of the results  E x p e r i m e n t s were in  conducted  b e h a v i o r and d i s t r i b u t i o n  and  so t h a t  Seasonal species was  differences  and s p e c i e s of fish  studied  could  between  experimental  I f individuals  positions  may h a v e  were  animals  h a d been t e s t e d  o f a group.  In spite  used  because  may  the preferred  t o those i n f e r r e d at a  from the  particular  not always r e p r e s e n t t h e p r e f e r r e d  of this  field  limitation  data are based  however,  groups  of  fish  on t h e b e h a v i o r o f  i n groups.  aquarium  varied  at d i f f e r e n t  fluctuated  within  which  were h e l d  fish  each  season  i n the holding seasons.  These  (Fig. 19).  was s h o r t e r  during  autumn.  The e f f e c t s  of variations  not  be f u l l y  evaluated.  However, p h y s i c a l  configuration, conditions  environment  were  bottom  gravel,  duplicated  was p a r t i a l l y  t r o u g h s and stream temperatures  i n these  than during conditions  conditions  depth, water  velocity  controlled.  spring could  s u c h as  i n a l l c a s e s ; hence t h e  but not f u l l y  also  The d a y l e n g t h a t  winter  and  light  on groups o f  singly,  The m a x i m u m n u m b e r  Temperatures  bottom  i n certain  data are based  been d i f f e r e n t  i n a gradient  position.  species  arrangements.  animals.  point  species  o f one  o f t h e two  conditions  changes  be r e c o r d e d .  on groups  The i n t e r a c t i o n  Distributional  distribution  could  w e r e made  i n summer a n d w i n t e r  seasonal  be o b s e r v e d i n e a c h  species  comparisons  at a time.  so t h a t  and  <  48. RESULTS 1.  R e p l i c a t i o n of Certain  and of  i n June  the control,  replicated the  series.  Observations  1963  (Fig. 25).  the cover  under w i n t e r  and d e p t h  conditions patterns  between  experiments  i n t h e c o n t r o l and c o v e r  (Fig. 25).  produced  similar  differences  they  gradients  pattern,  each  i n a skewed  usually with  the tank  "U"  f o r each  repeated  were In general, a n d 26).  the winter gradient  species  but the  gradient  experiments  t h a t were  exhibited  means  were i n the  identical,  characteristic  gradient  trout  i n the f i r s t  were  i n a two  sigmoid sections  changes i n d i s t r i b u t i o n  Comparison of the data s e r i e s of experiments  were more u n i f o r m  along  summer t h a n  i n fall  differences  i n sectional  Such  during  s h a p e d p a t t e r n , coho  highest  species  (Figs.25  i n the depth  distributions  species  each  and  (Fig. 25).  2. S e a s o n a l  seasonal  similar  gradient  patterns  Although  d i d not give  i n April  gradient  and t r o u t i n t h e d e p t h  (Fig. 26).  distribution  consistent i n repeated  I n t h e c o n t r o l and c o v e r  distributed  of  coho  were  observations  distribution  d i d reveal that  patterns.  were  Repeated  between  consistent  depth  species  the winter  ( F i g , 25 a n d 2 6 ) .  Differences  not  on t h e  Experiments with  gradient  duplicate distribution  series  during  i n t h e c o n t r o l e n v i r o n m e n t w e r e made t w i c e  repeated in  e x p e r i m e n t s were r e p l i c a t e d  the spring-summer coho  experiments  obtained  during  indicates that  the length of the tank  or winter  numbers o f i n spring  ( F i g s . 25 a n d 2 6 ) .  averages  occurred  l a r g e v a r i a t i o n s i n t h e average  the three  The  i n fall  number o f f i s h  fish and  greatest  or winter. per section  SPRING SUMMER  WINTER  FALL COHO STEELHEAD ©-  5 4  3  2  SECTION 25.  D i s t r i b u t i o n s o f coho a n d s t e e l h e a d i n " c o n t r o l " and "cover" gradients, described i nt e x t , during three seasons. D o t s a n d c i r c l e s r e p r e s e n t mean n u m b e r ' of f i s h ' p e r s e c t i o n o v e r a one d a y p e r i o d (10-15 observations). V e r t i c a l l i n e s i n d i c a t e range. S e c t i o n 1 r e p r e s e n t s t h e upstream end o f t h e aquarium.  50.  SPRING  FALL  -  WINTER  SUMMER  5  4  3  2  S E C T I O N  26.  Distributions o f .coho a n d s t e e l h e a d i n " l i g h t " , " d e p t h " and " d e p t h and v e l o c i t y " g r a d i e n t s , as described i n text, during three seasons. Circles and d o t s r e p r e s e n t mean number o f f i s h p e r s e c t i o n (10-15 o b s e r v a t i o n s ) . V e r t i c a l l i n e s represent range S e c t i o n 1 r e p r e s e n t s t h e upstream end o f t h e aquarium  51. were in  a result  one  both  as  along  summer b u t  i n the  (Figs.25  and  during  to  the  coho.  moving  about  moving  control.and the  spring  and  i n the  control,  searching  less,  and  to  the  light the  deepest  and  tank  In as  early  form  upstream  and  shift  into  aggregates,  end  of  the  gradients  seasonal  trend  s e c t i o n of  depth  the  assume  a more  in  c o n t r o l and  apparent  well  the  seasonal  shift  However, the  and  high  fish  light  for i t .  light  than  into  numbers of  The  of  the  in  the numbers  s e c t i o n was  which coho  25  and  of  usually 26  in  Considering are  not  along  Activity  roaming  the  tank  accounts  section 1 fish  i.e.  were u s u a l l y  The  gradient.  gradient. fish  and  searching  steelhead  of  active,  cover  shown i n F i g u r e s  and  fashion  i n s e c t i o n 1.  upstream  scattered distribution light  the  These  a preference  gradient  were  in a similar  upstream r e g i o n  of wandering  the  as  screen  the  numbers  steelhead  many t r o u t w e r e  p o s i t i o n s i n the  of  tank  VIII).  movement, i t a p p e a r s ' t h a t  gradient.  the  the  as  about the  r a t h e r than  steelhead  control,  the  spring  e a r l y summer y o u n g  and  end,  the  to  winter  fall  upstream  this  the  gradient  In  i s indicative  the  depth  along  aquarium  or  conditions.  bottom of  tended  cover  distributed  seasonal  half,  the  a shift  apparent  stable  the  they  o r g a n i z a t i o n , near  In  or winter  s c a t t e r e d i n the winter  (Appendices V I I  and  fall  congregate  winter.  and  gradients  and  c o h o was  In scattered  under  to  length.  coho were  26).  by  tank  o f many i n d i v i d u a l s  scattered across  i n autumn  aquarium  tank  the  i t s full  some s o c i a l  exhibited  tendency  species  Young  with  the  p o r t i o n of  spring well  of  for  i n the  in section  5  cover  . represents stones. for no  a preference  Steelhead,  the deepest seasonal  gradient  experiments  of the five  as i n f e r r e d  most  i n spring  similar  from  species  stones  were  greater.  most  were  ( i . e . response  not i n winter.  were  i n which  distributions  to cover  (see F i g . 1 6 ) . are s i m i l a r  are  i n the natural responses and d e p t h ,  i n a similar  environment. different,  stream  F i g s . 27, 28,  and  a l l o w t h e two winter.  young f i s h  fashion i n spring  Coho, 6 t o 8 weeks  the  i n the  of the mechanisms t h a t  gradients  during  i n which  i n the n a t u r a l stream  and d e p t h  distribution  divergent  i n t h e Salmon R i v e r  a r e more c o m p a t i b l e  space  the  and  Environmental  25 and 2 6 ) , t h e s e a s o n s  D i f f e r e n t environmental  and p o o l  (Figs.25  i n t h e Salmon R i v e r .  preferences  and i n t e r a c t  the cover  were  distributions,  to coexist i n close proximity i n f a l l In  summer  and e a r l y summer, t h e s e a s o n  and 3 2 ) , a r e i n d i c a t i v e  soecies  exhibited .  velocity  and  experiments,  experimental  t h e s e a s o n s when e x p e r i m e n t a l  laboratory,  but  overlapped  s p e c i e s meet  two  +  conditions  t h e s e a s o n when l a b o r a t o r y d i s t r i b u t i o n s  environment.  31  (Figs.  under spring  and w i n t e r  and i n f e r r e d  and w i n t e r  populations  the  Trout  i n the depth  experimental  was m o s t p r o n o u n c e d  Distributions  In  gradient.  preference  o f coho and s t e e l h e a d  between the species  preferences,  segregation  conducted  the distributions  i n each  differences  two  winter  of species -in g r a d i e n t s  However, i n autumn  During  a strong  the large  (Fig. 26).  conditions,  fall  c o h o , show  change i n d i s t r i b u t i o n  In  26).  like  s e c t i o n of the depth  3. C o m p a r i s o n  similar  f o r p o s i t i o n s under or around  52.  utilized and  summer  o l d , s c a t t e r e d among t h e  53.  stones  which  formed  spring  about  one t h i r d  taken  by coho were  positions  the cover  were  390 p o s i t i o n s  occupied  stones.  were  the rocks shelter  immediately  were  one t h i r d  downstream positions them  from  at fewer  were  old, distributed  (Fig. 28).  trout  were  aquarium  under  (Fig. 28).  from  them  were  a large  27 a n d 2 8 ) . A second  a different  During  immediately  end o f t h e recorded  were  were  In winter one-fourth of the positions and a p p r o x i m a t e l y  one-eighth  were  (Fig.28).  i n a h i g h degree  i n w i n t e r the tendency  (Figs.  28).  number o f young  of the positions  species i f together i n a cover  t o a degree,  themselves  stones, only s i xpositions  would r e s u l t  would,  not i n the  a n d none was u n d e r  i s evident that the distributions  condition  However,  (Fig.  i n the upstream  sixth  downstream from  It  between  One  were under s t o n e s  downstream  spring  the f a l l ,  among  o f coho, t h e other  among t h e s t o n e s ,  and remained  (Fig. 28).  them  recorded  During  active  immediately  As i n t h e c a s e  scattered  positions  at the sides of the tank.  of the steelhead positions  stones.  Many  downstream from the  Those t h a t were  at positions  3 t o 5 weeks  stones'.  I n w i n t e r 126 o f  t h e same p a t t e r n a s t h e 6 t o 8 w e e k c o h o  spring,  in  were  During  of 412) o f t h e p o s i t i o n s  among t h e s t o n e s .  ( F i g .27) i n t h e w i n t e r .  of stones  (Fig. 27).  downstream from  however r e c o r d e d  Steelhead, in  (126 o f a t o t a l  immediately  recorded  Fish  gradation  isolate  case  manner,  them  of trout  i n the  of contact  gradient.  of trout from  observed  to hide  coho w h i c h  However, i n under  stones  do. n o t do s o  a n d c o h o u s i n g t h e same  i n winter, occurs  i n the depth  space  gradient.  3*  COHO  H  1 C C V E R GRADIENT  — PLAN  VIEW  MAY 28  0  0  OCT  JAN 25  '•  ::.0  'O-.-'- ;:O..V-^ v  >..oV.  j  DIRECTION OF FLOW  <=  P.  •a ' •;•  la . . »  •o •  ,. .• • v Q ... • ;  •  •  •%Q  aO  *£>•••:  e:  • \  '  '•.[  ,€>:•  —  SECTION Fig.27.  D i s t r i b u t i o n o f coho:in cover gradient during three seasons. Locations o f 4 0 f i s h d u r i n g 10 c o m b i n e d o b s e r v a t i o n s a r e g i v e n . Groups o f dots r e p r e s e n t same f i s h o c c u p y i n g same l o c a t i o n r e p e a t e d l y o r d i f f e r e n t f i s h , i n t h i s and s u c c e e d i n g f i g u r e s o f t h i s t y p e . Points within the stone o u t l i n e s r e p r e s e n t f i s h under stones. Dotted l i n e s represent s c r e e n s a t ends o f aquarium i n t h i s f i g u r e and s u c c e e d i n g f i g u r e s o f this type.  -77-1  STEELHEAD !•  •••;>•  MAY 30  -  . — v  ;  • 0  IP •  ;o  • 0 . ; .  '  0  i—:  -J  •  G3  CD CD •  ":.  a -  : : , ••• r  •$  o  .  .  =.Q ••  • 0  •  '  •D  0  CP ••• •Q  VIEW  •o  "O  r=  JAN 27  — P L A N  j  v  o :  ^  GRADIENT  • '• —'  1  U;"C  SEPT 29 j  ] COVER  10  1%  :  :—:—:—••  ,  • •i-.s  • • • -o  • j  •o  •,  • • -'••-•••5 ;  SECTION Fig.28.  D i s t r i b u t i o n of steelhead i n cover gradient during three seasons. L o c a t i o n s o f 4 0 f i s h d u r i n g 10 c o m b i n e d o b s e r v a t i o n s a r e g i v e n . P o i n t s w i t h i n t h e stone o u t l i n e s represent f i s h under stones.  56. Figures coho  29  and  and  show t h a t t h e  steelhead  winter.  Table  difference and  30  lower  similar  shows t h a t  i n June  i n the  numbers of  young  of  sections 4  coho  and  5  increase  i n segregation  i s primarily  behavior  of  Vertical  (Figs,  31  and  distributions  32)  considered  (Figs.  steelhead  were  the  hand most  other  bottom  or  high  segregated  lower  V). as  depth  spatially  interspecific (Table  V).  practically  on  the  zones  depth  contests  were r e c o r d e d  o f ..the d e e p  zone.  at the  and  fighting basis  of  between the  s e c t i o n and  edges near  the  areas  along  When t h e  was  two  equal  aggression were  were  Intraspecific  under  and  summer c o n d i t i o n s  not d i s p r o p o r t i o n a t e l y  spatial  segregation- .  occurred  and  4.  coho  t r o u t on  in  coho  they  the  of  interspecific  than  contests  in sections 3  On  deepest  when t r o u t and  lower  section.  ( F i g . 33)  ( F i g . 34)  most  the  areas.  summer  the  species  winter  A l a r g e amount  together  were  in  horizontal  deep  defended  i n these  winter  a l l interspecific  edges of  side  species  This  both  i n the  already, described.  Interspecific  of  side of  upper  tests).  a change  i n the  each  during  gradient  aggression  expected  to  show t h a t  intraspecific  as  t r o u t i n the  distribution  up  in  during winter.  due  of  significant  (Chi-square  bottom  occurred  During  is a  and  distributed  both  together  amount o f  i n the  the  each depth  fighting  (Table  30)  coho were  were p l a c e d  numbers the  placed  over  different  i n conjunction with  aggregations  edge o f  intraspecific  was  and  I n d i v i d u a l s of  downstream  species  29  spread  i n loose  section.  there  i s h o w e v e r more p r o n o u n c e d  steelhead.  distributions  i n s p r i n g , but  IV  halves  Segregation  are  horizontal  Few  at the  downstream  aggressive  i n aggregations  the  However  bottom.  at  the  57. Table  IV.  N u m b e r s o f c o h o (C) a n d s t e e l h e a d . ( S ) i n u p p e r and l o w e r h a l v e s o f s e c t i o n s 4 and 5 i n t h e d e p t h gradient.': i n e a r l y summer a n d w i n t e r (j.uhe a n d January).  June  January  C  S  C  Upper h a l f  124  75  168  24  Lower  103  145  161  281  half  S  COHO  DEPTH GRADIENT — PLAN VIEW  JUNE 26  OCT 3  DIRECTION OF FLOW  <  e:  JAN IO  Fig.29.  D i s t r i b u t i o n o f coho i n d e p t h g r a d i e n t d u r i n g t h r e e s e a s o n s . L o c a t i o n s o f 40 f i s h d u r i n g 10 c o m b i n e d o b s e r v a t i o n s a r e g i v e n . Rows o f p o i n t s at s e c t i o n b o u n d a r i e s r e p r e s e n t f i s h o c c u p y i n g p o s i t i o n s a l o n g t h e edges o f t h e d e p t h z o n e s .  DEPTH GRADIENT — PLAN VIEW  STEELHEAD JUNE 22  OCT 5  DIRECTION OF FLOW «  JAN 12  3 SECTION 30.. D i s t r i b u t i o n o f s t e e l h e a d i n d e p t h g r a d i e n t d u r i n g t h r e e s e a s o n s . L o c a t i o n s o f 40 f i s h d u r i n g 10 c o m b i n e d o b s e r v a t i o n s a r e g i v e n . Rows o f p o i n t s a t s e c t i o n b o u n d a r i e s r e p r e s e n t f i s h occupying p o s i t i o n s a l o n g edges o f d e p t h zones.  COHO  DEPTH  JUNE 26  OCT  —LATERAL  3  VIEW  i DIRECTION OF FLOW  <  V—-  JAN IO  SECTION  Fig.31.  GRADIENT  D i s t r i b u t i o n o f coho, l a t e r a l v i e w , i n depth gradient during three seasons. Locations of 4 0 f i s h i n 10 c o m b i n e d o b s e r v a t i o n s a r e g i v e n .  ei  STEELHEAD  -asDEPTH GRADIENT  JUNE 22  OCT 5  —LATERAL  4"  '••  DIRECTION OF FLOW  JAN 12  S E C T I ON  Fig.32.  VIEW  D i s t r i b u t i o n o f steelhead, l a t e r a l view, i n depth gradient during three seasons. L o c a t i o n s o f 40 f i s h i n 10 c o m b i n e d o b s e r v a t i o n s a r e g i v e n .  <  €1  JUNE  28  DEPTH GRADIENT —PLAN  VIEW  COHO  STEELHEAD  COHO  — LATERAL VIEW  >——  STEELHEAD  3 SECTION Fig.33.  DIRECTION OF FLOW < €1 -I  . R e l a t i o n s h i p o f coho and s t e e l h e a d c o m b i n e d i n d e p t h g r a d i e n t d u r i n g summer c o n d i t i o n s . L o c a t i o n s o f 20 c o h o p l u s 20 s t e e l h e a d . i n 10 c o m b i n e d o b s e r v a t i o n s are g i v e n .  JAN 17  DEPTH GRADIENT —  PLAN  VIEW  COHO  STEELHEAD  L A T E R A L VIEW  COHO  DIRECTION OF FLOW  STEELHEAD  <  3  SECTION Fig.34.  R e l a t i o n s h i p o f coho and s t e e l h e a d combined i n d e p t h gradient during winter conditions. L o c a t i o n s o f 20 c o h o p l u s 20 s t e e l h e a d i n 10 c o m b i n e d o b s e r v a t i o n s are g i v e n .  €1  64.  Table  V.  A g g r e s s i v e c o n t e s t s p e r f i s h p e r 100 m i n u t e s d u r i n g June and J a n u a r y 1963. S y m b o l s a r e as f o l l o w s : C  Date  - coho,  June  steelhead,  OC  - coho  attacking  coho,  OS-  - coho  attacking  steelhead,  S»S  - steelhead  attacking  steelhead  S«C  - steelhead  attacking  coho.  N  u  Fish _  S -  m  b  e  r C o OC  o n  t OS  f e  s t S'S  • -  C  S  28  20  20  12.7  6.1  6.3  20  20  4.4  1.3  2.4  January  17  and  s S'C  1.3 0.9  Minutes Observation  90 90  65. 4.  Description Young  similar are  coho  postures  listed  of  and  and  i n the  agonistic  behavior  steelhead  movements.  "Materials  These  and  and  are  i t i s e s s e n t i a l to  classification. variety of  the  of  q u a n t i f i c a t i o n of  Each  of  forms which  behavior.  In  the  and  acknowledged that  this  type  on  scale  a more r e f i n e d  components. number o f  S u c h was  fish  that  Lateral Kalleberg dorsal of  apparatus  for  the  b o d y was  for  a lateral  of  the  back.  although large  This  the  median The  Kalleberg  or  either  fish  or  one  of  be  and  a lowering  of  (Fig.35).  The  s t r a i g h t or  was  the  erected were  usually  long,  from  dorsal two  slightly  edges  described  by  (Fig.  ( F i g . 36A),  to  of criterion  the two  line species,  the  possess.,  35C).  Fabricius  and  the  coho w h i c h  i n which the  f i n compressed  and  erection  line  f i n and  in  the  action.  of  The  s i m i l a r f o r the  a posture  seconds  dorsal  more o b v i o u s  colored  the  of  basihyal  recurved.  dorsal  of  (1953)  fins  seconds  classified  erection  the  each is  because  Fabricius  a simple  a  duration  a prolonged  15  It  r a p i d i t y of  by  in  behavior  could  study  the  intensity  seconds to  (1958) v a r i e d  for  the  i n t e n s i t y or  the  of  appears  two  frontal display,  extended  basis  or  with  the  components  from  displays  arched,  and  any  indicated.  behavior  described  Lateral  slightly  to  description  feasible in this  was  fins  related  quantifying  display  display  the  of  movements  varied  one  paired 10  be  were o b s e r v e d  f i n , lasting and  not  behavior  variability  of  d i s p l a y was  (1958).  dorsal,  the  by  the  and  Before  understand  following  component i s d e s c r i b e d  displays  a number  d i f f e r e n t components  appear to  the  using  Methods".  classification attempted,  display  (1953)  back  and  was  basihyal  a posture  in  which  66.  Fig.35A.  Coho,  c a 10 m o n t h s  old,i n lateral  threat  posture.  B. S t e e l h e a d , c a 8 m o n t h s o l d , i n l a t e r a l p o s t u r e ( s e e f i s h on t h e l e f t ) . F i s h on t h e r i g h t i n f r o n t a l threat posture of low i n t e n s i t y . C.  Coho,  ca 2 months  old,i n lateral  threat  posture.  67  ig.36A.  Coho, ca 2 months o l d , i n f r o n t a l t h r e a t p o s t u r e o f low i n t e n s i t y ( r i g h t ) . Coho, ca 2 months o l d , i n w wag p o s t u r e ( l e f t ) .  B. C o h o , c a 2 m o n t h s o l d . i n w i g w a g threat posture ( r i g h t ) .  ( l e f t ) and  latera  68.  1  the  b a c k was  strongly  the  basihyal  well  In usually  the  display  w i t h median  and  paired  body  at  this  display  a 20  to  lateral 30  the  i n displays  displays  fully,  degrees)  and  a wig  the  after it  another  was  of  Nips definite  so  was  hard  inclination  the  As  wag  those  individual the  more  chase  and  flight.  i t past the  to  bites  i n which  fish  which  from  2 or  there  In other  s e e m e d t o be  case  i n coho  I f one  of  criterion  i n the  of than  3  briefly  short  m.  appeared  cases  darted  i t fled  slow  I n some i n s t a n c e s f i s h  attacked.  animals  The  30  color.  ranged  chases  were  inclined  p o i n t from  Pursuits long  and  of  was  (near  striking  i n f i n shape  chasing. cm  was  In  wag  fins  accentuated.  swimming movements.  ( F i g . 37).'  that  was  the  angle  In wig  the  the wig  swam  swimming movement  erected fins,  pursued  were  The  steep  o r 30  contact  "mouthed" t h e were  20  varied.  short duration.  movements were  and  ( F i g . 36B).  of  d e s i g n a t e d as  excursions  of  of  posture,  h e a d down and  angle  involved  and  extended,  horizontal  f i n erection  differences  Chasing  well  a lateral  the  display  of  adopted  from  and  (unmeasured) p e r i o d s .  of high i n t e n s i t y )  display,  because  angle  compressed  t o be  accentuated  lateral  trout  the  fins  amplitude  were  lateral  wag  and  the  that  (inferred  erected  posture  degree  and  fish  fully  movements w i t h t h e  amount o f  body i n c l i n a t i o n  dorsal  for longer  wag  accentuated  for  extended  the  wig  with  low  arched,  t o be  a  only the  bites  stuck  together. Threat  n i p s were  Such b i t e s  appeared  t o be  as much  20  cm.  as  o r 30  nips which inhibited  were and  I n some c a s e s  aimed  at o t h e r  hence m i s s e d a fish  fish.  contact  swam a s h o r t  by  F i g . 3 7 . N i p p i n g i n t h e p a i r o f f i s h on t h e l e f t . Picture taken a f r a c t i o n o f a s e c o n d b e f o r e t h e f r o n t f i s h was nipped. Second p a i r of f i s h ( r i g h t side) i n c h a r a c t e r i s t i c lateral postures.  70. distance  and n i p p e d  situations of  they  i n the direction  turned  a neighbouring  their  heads  o f another.  and n i p p e d  turned  lunge  w h i c h were to  i t s head  at i t .  brief,  An  described  and  methods  other  aggressive  section.  components  o r made  Some  contests  were  components,  bouts  aggressive  often  short  and i n v o l v e d  others  were  i n terms  of individual  components  the rate  as w e l l into  and s p e c i e s .  38 r e p r e s e n t s  rate  these are  three  may b e r e l a t e d  three  main p o i n t s  repertoires  seasons.  VI.  of occurrence  behavior  o f each  i n the figure  c o m p o n e n t , ..they  t o each other illustrated  o f t h e two s p e c i e s  r e p e r t o i r e s o f coho and  Details of observation  The d i a g r a m s  during  show  time only  do n o t s h o w h o w  aggression.  i n Figure  differ  contests.  a l l i t s components  seasons  i n different  the  each  behavior  as c o m p l e t e  aggressiveness  i n Table  l o n g and  of.occurrence  and q u a n t i t y o f  given  several of  i n the materials  quality  are  nips.  involving  made i t p o s s i b l e t o c o m p a r e  during  difficult  individuals.  breakdown o f a g o n i s t i c behavior  steelhead  short  a n d d i s p l a y s i n t e r s p e r s e d among  i t was p o s s i b l e t o e x a m i n e  Figure  a  fish  movements,  and t h r e a t  bout  a  behavior  recording  individual  These  c o m p o n e n t s was g i v e n  behavioral  Analysis of  i n which  and were  behavior  o f an a g g r e s s i v e  series of bites  By  The  non-social  and r e c i p r o c a t e d between 5.  of  from  two o r t h r e e  involved  another  v a r i e d as d e s c r i b e d  example  the  only  q u i c k l y toward  No t h r e a t n i p w a s i n v o l v e d .  distinguish  i n the direction  fish.  I n t e n t i o n movements were r e s p o n s e s only  In other  38.  There  First, the  at a l l seasons.  Second,  71  STEELHEAD  COHO L  M  WW  SPRING C  z 2 O O  —  SUMMER  HS cc UJ  a.  IO ^ cc  5 iu a. LU  •O  I<  CC  L " LATERAL  FALL  WW"  WIG WAG  F"FRONTAL C " CHASE  N " NIP TN "THREAT NIP I M"  INTENTION MOVEMENT  WINTER  38.  Rate o f o c c u r r e n c e o f i n d i v i d u a l components i n t h e a g o n i s t i c b e h a v i o r o f young coho a n d steelhead. Data a r e based on combined observations o f f i s h in.the f i v e experimental arrangements used. See t e x t f o r d e s c r i p t i o n of behavior components.  72.  Table  Coho  VI. M i n u t e s o f o b s e r v a t i o n o f coho and s t e e l h e a d i n c o n t r o l and four experimental arrangements d u r i n g s p r i n g , f a l l and w i n t e r .  Steelhead  Season  750  410  Spring  390  440  Fall  890  720  Winter  73. within  each  seasonally behavior  species from  relatively  most  strong  during  spring  Level spring, trout  summer  species  d i f f e r e n c e s were t h e  The l a t e r a l  and autumn  seasonally.  c o m p o n e n t s o f t h e t r o u t as  d i s p l a y , which  i n t h e coho t h a n  movement  often  preceded  i n the steelhead  (Fig.38).  of aggressive and f a l l ,  aggressiveness  of  changes  and c h a s i n g  stronger  decreases  Third, the quality  w i g wag, t h r e a t n i p and i n t e n t i o n  o f coho.  w i g wag, was  behavior  species  obvious nipping  to strong  components the  spring to winter.  e x h i b i t e d by each The  opposed  t h e amount o f a g g r e s s i v e  behavior  i t decreased  decreased  among  coho was h i g h i n  during  winter.  p r o g r e s s i v e l y from  Among  spring to  autumn and w i n t e r . During and  chasing  were  spring  frequent  components were v e r y spring  a n d summer.  most.similar winter  most the  Hartman  behavior  composition  and. c h a s i n g  (Fig.38),  (1963)  change  i n the steelhead  of elaborate  was e v i d e n t  i n t h e coho.  lateral young  f r e q u e n t l y , but nipped At higher  was  By  i n t h e coho.  and The  c o n f i g u r a t i o n was  component.  frequency  showed t h a t  (8 t o 9 c m / s e c ) .  during  o f t h e two s p e c i e s  a n d w i g wag e l e m e n t s  o f t h e t r o u t were  displayed  Nipping  d i s p l a y components were g r e a t l y r e d u c e d  o f t h e chase  A higher  elements  species.  i n the steelhead  Behavior  seasonal  reduction  contact  strong  by t h r e a t n i p s  evident  i n both  displays, nipping  i n t h e s p r i n g , by autumn i t . h a d d i v e r g e d .  the lateral  equalled  a n d summer l a t e r a l  d i s p l a y s and n o n The m a i n  displays, biting  brown t r o u t less  velocities  behavior and  chasing.  (Salmo t r u t t a  at low water  Linn,}  velocities  (18 t o 19 cm/sec and  74. 28-30 The  cm/sec) they  mechanical  with  median  reason  of  of holding  position i n the  steelhead  adapted  Results  with  took  of f i e l d  major  i n the f i e l d  appeared  there  i n riffle,  than  patterns  that  steelhead and  chases,  the behavior  suggest  and p o o l  of  nipping.  that the  are r e l a t e d to  c e r t a i n behavior  adaptive  current  and coho  Distributions indicate that  environmental remain  separate. areas  species  (Figs.  and p o o l  conferred  habitats  allowed  whether  advantages  ( F i g s . 39 and  or that  more  and coho h a d  and p o o l  some  individuals to  similar  h a b i t a t s when t h e  species  h o w e v e r , were more numerous i n t h e  39 and 4 0 ) ,  i n J u l y experiments,  to determine  preferred pools  Both t r o u t  Steelhead,  and an  i n pools.  i n riffle  i n the r i f f l e  In  species  conditions  which  r e g u l a t i o n of behavior  i n the pools.  distributions  riffle  both  habitats.  of each  analyses  characteristics  o f t r o u t and  and p o o l  features  to particular  were b e h a v i o r  habitat  difference i n distribution  was r e l a t e d t o r i f f l e  trout i n r i f f l e s  mixed  of behavior  and s t e e l h e a d  a t t e m p t w a s made i n t h e l a b o r a t o r y  were  character  displays, nips  studies  o f coho  current  ecology.  laboratory  40)  on a d i f f e r e n t  conditions  less.  t o be t h e m a i n  brown t r o u t , s u g g e s t s  and l a b o r a t o r y  i n behavior  The  on  appeared  A comparison  to rheocrene  6. D i s t r i b u t i o n  the  extended  and d i s p l a y e d  i n v o l v e s more w i g wag d i s p l a y s a n d l e s s  differences  coho  fins  involving primarily lateral  coho w h i c h  their  difficulty  agonistic behavior  coho.and  more  more  water v e l o c i t i e s .  behavior, is  relatively  and p a i r e d  that  at h i g h e r  nipped  When c o h o  density  and s t e e l h e a d  of steelhead  was  were  reduced  Fig.39.  of  Distribution  c»h»  four  different  pool  environment  represent  fish  broken  species  lines  number o f f i s h  pool  Scale i s half  Fig.24  (July).  and  t h e a v e r a g e number o f  and  (see  i n riffle  dots  section,  mixed  densities  at  Solid  per  mixed.  and s t e e l h e a d  separate.  indicate  t h e average  per section, f o r the points that  environment).  species f o r species  f o r species  for details  Circles  separate,  of r i f f l e  and  75.  COHO  STEELHEAD  20 FISH  40 FISH  60 FISH  80 FISH  2 1 5 4 3 2 SECTION  I  Fig.40.  Distribution  o f coho  four  different  pool  environment  dots represent fish  and s t e e l h e a d  densities  in riffle  (November),  the average  per section,  species  and b r o k e n  average  number p e r s e c t i o n ,  mixed.  Scale  (see  i s half  number o f  indicate  of  the  species f o r species  f o r species  Fig.24 f o r d e t a i l s  environment).  Solid  f o r the points that  and  separate.  Circles  mixed  lines  at  separate,  riffle-pool  76.  COHO  STEELHEAD  20 FISH  uJ  40 FISH  IO O  UJ X  UJ 00  to  to  UJ  UJ u  o  £20 to  60 FISH  z O  IOH  z O  l-  o  o  UJ  to  UJ  a  a  UJ 3 0  n  aO z  UJ  UJ 2 0 T  80 FISH  3  IO  5 4 3 2  T  r  -I  1  :—I  1 54 32 SECTION  r  1  77. (in  relation  to the s i t u a t i o n  6 out of 8 cases of  12 i n s t a n c e s  reduced alone) out  i n the pool  to'the  habitat.  situation  i n 9 o u t o f 12 c a s e s  o f '8 i n s t a n c e s  the species  Coho where  i n the r i f f l e s  i n pools.  Upon  mixing,  i n the pools  steelhead  d e n s i t i e s changed i n the o p p o s i t e  than  expected  During not  clear  mixed, and  increased  instance.  7.  winter  i n July  as was  maintained and  test).. mixing  the species  i n the pool  i n mixed  Changes  were  were  i n section  sections i n a l l but  in riffles  to this  were  was  i n winter  observed  w h i c h may themselves  actually  i n more  1,  one  groups,  was  i n relative to those  of  and  pools  higher  in riffle were  the case  habitat •  separate  of steelhead  under  F i g h t i n g and d i s p l a y i n g . o c c u r r e d more  Interspecific on b e h a v i o r  and  direction  c o n d i t i o n s when t h e s p e c i e s  i n summer- t h a n  environment  in 5  (Fig. 39).  of aggressiveness  An e x c e p t i o n  was  coho d e n s i t i e s  consistent relation  behavior  conditions.  frequently  no  the species  of i n t e r s p e c i f i c  i n section 4 also.  Aggressive  41).  the e f f e c t s  riffle  d e n s i t y , was  .05, C h i - square  density of steelhead,  as o c c u r r e d  i n the pool  (P =  i n  i n 8 out  i n the r i f f l e s ,  I n e x p e r i m e n t s where  o f coho showed  Levels  (Fig.  chance  i n the three  However  steelhead  and d e c r e a s e d  d e n s i t i e s decreased  i n the pool  density  than  winter  (Fig, 40),  steelhead  higher  by  alone)  and i n c r e a s e d  increased  cases  was  h a b i t a t , and i n c r e a s e d  i n the r i f f l e  (inrelation  where  reduced  i n the r i f f l e  i n the experimental  mixing  revealed  i n a large  utilization  e x p l a i n why  sections of the  of-this  space  pool  gradients.  an e n v i r o n m e n t a l  degree  i n the r i f f l e  and  by  effect  trout aquarium  coho.- F i g u r e 4 2  78.  POOL  20-  •  H  JULY NOV  O-  z  10-  RIFFLE  20-  CvC .41.  SvS  Rate o f a g g r e s s i v e b e h a v i o r i n r i f f l e and p o o l h a b i t a t s d u r i n g J u l y and November. D a t a b a s e d o n o b s e r v a t i o n s made w i t h s p e c i e s separate. C v C i n d i c a t e s coho a t t a c k i n g coho, and S v S i n d i c a t e s s t e e l h e a d a t t a c k i n g steelhead. Coho o b s e r v e d 390 m i n u t e s i n J u l y and 340 m i n u t e s i n November, s t e e l h e a d o b s e r v e d 380 m i n u t e s i n each p e r i o d .  79.  POOL •  Z  2  JULY NOV  IO  o o  cc UJ Q. I CO  5-  cr ui a to I-  UJ O  °  5-j  IO-  CvC  Fig.42.  CvS  SvS SvC RIFFLE  R a t e s o f a g g r e s s i v e b e h a v i o r i n r i f f l e and p o o l h a b i t a t d u r i n g J u l y and- N o v e m b e r . D a t a b a s e d o n e x p e r i m e n t s i n . w h i c h s p e c i e s were mixed i n equal numbers a n d o b s e r v e d 270 m i n u t e s i n J u l y and 250 m i n u t e s i n November. , Meaning o f symbols as f o l l o w s : C v C coho a t t a c k i n g coho, C v S - coho a t t a c k i n g steelhead, S v S - steelhead attacking steelhead and S v C - s t e e l h e a d a t t a c k i n g coho.  80. shows t h a t  coho d i s p l a y e d a h i g h  intraspecific trout  was  square  aggressiveness  values  indicate  that  In  the r i f f l e  steelhead  41  h a b i t a t of the aquarium  on t h e o t h e r  42).  to defend  environment  degree  mixed  case  i n riffles  groups.  (species areas.  riffles.  current  sections large  c u r r e n t was  stones.  induced,  i n July,  behavior  induces  41  Agonistic activities  High  o f coho  densities  The  was  more  was  not the  riffles in  such  to the  density regulation i n territorial (Kalleberg, 1958).  objects induces  (Hartman,  and t h e r e  and  and 4 2 ) .  of f i s h  more d i s t i n c t  of reference  Figures  increased  such  i n the  1963).  fish  In the  to riffle  were r e f e r e n c e  objects,i . e .  i n these  were  areas  hence i n F i g u r e 43 r a t e s o f a g g r e s s i o n  densities.  was  fighting  i n low densities  territories fast  steelhead  in a riffle  i n riffles  as has p r e v i o u s l y been d e m o n s t r a t e d  and d e f e n d  combative,  the l e v e l  (see F i g s .  f o r the s t r i c t  a d d i t i o n the presence  establish  species  steelhead  separate  .01).  aggressive  d i f f e r e n c e s , w h i c h were r e l a t e d  accounted  Strong  tendencies  groups  i n November t h a n  unmixed) r e s u l t e d  environment,  P  A comparison of  of reducing  rates of aggressive  Behavior  aggressiveness  not  aggressive,  t h e two  of steelhead  when t h e s p e c i e s were High  coho were  of  (Chi-  and i n c r e a s i n g i t i n p o o l s .  I n mixed  i n the pools  (Fig. 42).  i s significant.  territories.  had the e f f e c t  of aggressiveness  frequent  low  temporary  more  and  Aggressiveness  hand were p a r t i c u l a r l y  In a d d i t i o n to being  aggressiveness  In  and p o o l s  and 42 i n d i c a t e s t h a t m i x i n g  pool  in  within pools.  differences i n rates of  t r o u t and coho i n r i f f l e s  tended  of i n t e r s p e c i f i c  correspondingly low i n the pools  of  (Fig.  level  of f i s h  were  d i d not occur  easily'  h i g h at' because  81.  POOL  RIFFLE  JULY • O NOV  30-  z  UJ g <  1  0  o  STEELHEAD  o o °o  » •^cy #  gF» o  9-  COHO  20  40  FISH Fig.43.  2 0  PER  SECTION  4 0  (l.2 M )  Relation o f rate of•aggressive behavior t o density of fish. Coho a n d s t e e l h e a d • c o m p a r e d i n r i f f l e and p o o l h a b i t a t s d u r i n g two s e a s o n s . E a c h d o t o r c i r c l e r e p r e s e n t s 10 m i n u t e s o f o b s e r v a t i o n i n one s e c t i o n o f t h e a q u a r i u m . (Data o b t a i n e d w i t h s p e c i e s s e p a r a t e ) .  82. increased  fighting In  increase  the  l e d to  pools  in fish  'in  small  with  still  increase  (Fig.  43).  this  i n n u m b e r s was  was  threat posture.  distance  one  fish,  ahead  the  second  of  dropped  44A,  B  and  literally If  the  brushing  occurred.  with  formation  the  dominants  at the  illustrated  did  coho.  increase because and were  became not  dominant  the  trout,  they  the  back w i t h the  for  coho, front.  In  to  other  each for a  second fish  fish  victor,  by,  (Fig. little  closely  groups w i t h  which (Figs.  ended  i t s tail  short  darted  display in  t h r e a t was  44C). more  associated  one  to  three  behind  them  45, establish  stable  Such  took  settled  began to roam  groups  decreased  a change  many s t e e l h e a d  others  social  aggressiveness  steelhead.  attacked.  wag  several subordinates  d i d not  quiet while  coho  individual,  upstream  behind  wig.- wag  n u m b e r s w e n t up  often  a wig  toward  In J u l y observations  as  swam p a r a l l e l  stable social  i n numbers of  a group  dominant  remained  i n Figure  in  A f t e r swimming p a r a l l e l  f r o n t and  Steelhead  In  often  i t s opponent  of  evident  salmon  aggression  of  performed  The  of  coho.  downstream  displaced fish  Atlantic  i n rate  an  Yamamoto  account  I n many c a s e s  fighting  as  and  with  features probably  u s u a l l y the  backward C).  Reduction  with  and  f o r p o s i t i o n s near the  for positions, fish  lateral  decreased  Keenleyside  particularly  of  strongest  fish.  same e f f e c t  aquaria.  phenomenon i n g r o u p s  fighting  it  almost the  water  of  aggressiveness  (Fig. 43).  Certain behavior  competition  in  however  density  (1962) d e m o n s t r a t e d  displacements  to  about.  There were u s u a l l y l a r g e ,  d i d not  often  exhibit  the  wig  as with  place the  bottom  These  fish  potentially wag  threat  83  Fig.44A.  C o h o , c a 10 m o n t h s o l d , i n w i g wag p o s t u r e . F i s h a t l e f t i s d i s p l a y i n g and b e g i n n i n g t o drop back toward f i s h at r i g h t .  B.  Both f i s h d r o p p i n g downstream closer together.  and  coming  C.  C o h o a t l e f t s t i l l i n w i g wag p o s t u r e , i t s t a i l almost s t r i k i n g f i s h at r i g h t . At t h i s p o i n t t h e f i s h a t l e f t may w h e e l a n d n i p t h e s e c o n d f i s h o r s e c o n d f i s h may flee.  Fig.45.  S m a l l g r o u p o f 8 coho w i t h one d o m i n a n t ( s e c o n d f r o m r i g h t } and s e v e n s u b o r d i n a t e s . Small f i s h o c c a s i o n a l l y a v o i d e d a t t a c k by r e m a i n i n g still a n d r e s t i n g d o w n among t h e s t o n e s , s e e f o r e g r o u n d .  85,. and  d i d not 8.  hold  Summary o f Field  distribution with  these  density.  below  S P R I N G AND Field  1.  changes  and  revealed  as  young  i n water  experiments  an  apply  Field  and  coho  pointed  groups.  and  to  changes i n  trout. and  population of  w h i c h were r e l a t e d  to  laboratory results  to  the the  are  Discussion. Salmon  the  Concomitant  features  i n t r o d u c t i o n to particularly  seasonal  temperature,  social, behavior  i n nature.  observations  1.  observations  were  stable  results  Laboratory  occurring  f r o n t p o s i t i o n s i n any  r e l a t i o n s h i p s of  environmental  briefly  the  changes summarized  Field  River.  E A R L Y SUMMER Laboratory  observations  Species largely segregated in different micro-habitats.  1.  observations  Both s p e c i e s have s i m i l a r distributions in experimental gradients.  2.  Both u t i l i z e space i n a n d c o v e r i n t h e same manner.  3.  Both species e x h i b i t high l e v e l of aggression which i n v o l v e s much b i t i n g and chasing.  Coho r e l a t i v e l y l a r g e compared to t r o u t .  4.  Temperature  Temperature of water 8.3° - 17.2°C, ( t i m e p e r i o d corresponds to l a b o r a t o r y period).  5.  Body  2.  Coho i n p o o l s , riffles.  trout in  3.  P o p u l a t i o n d e n s i t y per of area i s high.  4. 5.  unit  and  10°  to  f i n colors  t  pools  16°C.  vivid.  86 v  2.  FALL Field  1.  observation  Laboratory  Species p a r t i a l l y segregated in early f a l l , coming t o g e t h e r more i n l a t e fall.  1.  observation  S t e e l h e a d and coho have different distributions in experimental gradients.  2. C o h o i n p o o l s , t r o u t d e n s i t y about even i n r i f f l e s and pools.  2. S p e c i e s u t i l i z e s p a c e a n d c o v e r i n a b o u t t h e same manner.  3. P o p u l a t i o n r e d u c e d i n p o o l s , r e d u c e d more i n r i f f l e s .  3. C o h o a g g r e s s i o n h i g h , b u t l e s s b i t i n g and c h a s i n g is exhibited. Steelhead aggression lower than i n spring, relatively less chasing.  ;  4.  Trout s i z e range approximating that  5. T e m p e r a t u r e t o 12.5°C.  4.  Temperature  9° t o 1 4 . 5 ° C .  o f coho,  of water  7,2°  5. B o d y a n d f i n c o l o r s vivid.  less  WINTER  1.  S p e c i e s e x h i b i t no microhabitat segregation.  2. H i g h e s t species  d e n s i t y of both i n the pools.  1.  S p e c i e s have d i f f e r e n t distributions i n experimental gradients.  2. T h e y u t i l i z e s p a c e i n p o o l s and around cover i n d i f f e r e n t manners.  3. P o p u l a t i o n d e n s i t y r e d u c e d further i n pools, very low in riffles.  3. A g g r e s s i o n v e r y l o w i n b o t h s p e c i e . s . Coho d i s p l a y components are s t r o n g , v e r y l i t t l e b i t i n g and c h a s i n g . S t e e l h e a d show o n l y two components strongly; simple d i s p l a y s and b i t i n g .  4.  4.  Trout size range approximating that  5. T e m p e r a t u r e 7°C.  of  of water  Temperature  0.5°  t o 7.5°C.  cohos. 0.3° t o  5. B o d y a n d f i n c o l o r s l e s s v i v i d t h a n i n s p r i n g and fall.  87. DISCUSSION  An  animal's  behavior  i s adapted  just  as i s i t s m o r p h o l o g y and p h y s i o l o g y .  both  environmental  relate  to their  and  ecology.  behavior  o f coho  entering  t h e main body  directly  with  A.  Behavior  and t r o u t  natural  Trout  utilizing  a wider  condition  coho were  and t r o u t  differences,  two  were  account  species  numbers  o f young  River.  Chapman  result of  best  young  coho  aggression  were  though  density  (1958)  showed  of stream adapted  (1962) has and  that  density  and  deal  and  more  occurred  size  of A t l a n t i c  spring  During  such  of  experimental  i n riffles.  These and  summer,  stability May  of the  and June  i n the  The  i s the  ...emigration  a t a s e a s o n when l e v e l s  of trout were  was  least  decreased with  salmon f r y .  Trout  of  ritualized.  d i d not occur high.  large  Salmon  displacement  f o r space.  and when b e h a v i o r  of aggression  capable  of  positions i n  downstream  shown t h a t  frequently  Under  i n population  streams.  Ecology  to c e r t a i n types  appeared  during  displaced  territory  to their  to maintaining  evident  displacement  and r a t e  which  before  most  habitats.  competition  streams  highest  restricted  positions  coastal  coho were  from  considered  coho were  scattered  for differences  Downstream  population  conditions  a r e most  of aggression  and t r o u t  are  interaction.  to holding  i n small  be  there  of the ecology  and Coho i n R e l a t i o n  more  array  which  o f coho  aspects  now  i n g r o u p s w h i c h were  habitat.  probably  will  Accordingly  of the discussion, which w i l l  of Steelhead  distributed  responses  Certain  interspecific  Under  pools,  social  to i t s environment  even  Kalleberg increased i n the  Salmon  88. River  may  accommodate  territory displace data  size.  Coho, w h i c h  surplus  pushed or.be  against  such  completely.  the  other  tended  hand moved  differences  The  winter  to form  emigration revealed  occurred  o f groups  the  winter.  The  amount o f b i t i n g  contact in  (Figs.  laboratory  others  near  group.  Coho on  ( F i g . 4 6 ) . These  aggressive  i n dense  In winter  areas  and c h a s i n g  downstream studies-  facilitate  of the stream  were  lower  groups. i nthe  no  Laboratory  phenomena w h i c h w o u l d  of aggressiveness  during  i n both  was l o w i n p r o p o r t i o n  The w i g wag d i s p l a y o c c u r r e d  species.  t o non-  frequently  a n d was e x h i b i t e d i n c o n t e s t s f o r  the f r o n t o f a group.  F i s h w h i c h were  t h e w i g wag t h r e a t w e r e  group o f subordinates  experimental  i s usually reflected  25 a n d 2 6 ) .  i n restricted  conditions  using  of  i n t h e Salmon R i v e r .  aggressiveness.  position by  Levels  the type  are u s u a l l y found  groups  several behavioral  stability  space  and t r o u t .  coho  such  distributions  pool  d i f f e r e n c e s i n amount o f  and.with  e x h i b i t e d by coho  tendency  coho,  or laterally,  downstream o r l a t e r a l l y ,  winter  maintain  of retreat following  trout i n the  t o move u p s t r e a m  are consistent with  During  to  As a r e s u l t  The d i r e c t i o n  may  Experimental  downstream t o unused  Retreating  downstream displacement behavior  to pools,  i n a consideration of the matter of  downstream displacement. aquarium  changing  i n d i v i d u a l s w o u l d be u n a b l e  w o u l d move  c o m b a t may b e i m p o r t a n t  stream  are r e s t r i c t e d  trout i n the r i f f l e s .  out of pools, displaced  i n numbers by  i n d i v i d u a l s out of the pools.  indicated that  positions  f o r changes  pushed  b u t were n o t d r i v e n  back  entirely  displaced into the  out of the  ESI  COHO  •  STEELHEAD  cn 4 0 I<  UJ  CC  H UJ  cc u_ O  20j  LATERAL  I  DOWNSTREAM  UPSTREAM DIRECTION  .46. D i r e c t i o n (based'on i s s u i n g  OF  RETREAT  of-retreat  o f coho  w^'+'H"  a  c'oho)?  ^  S  S  t  S  '  and s t e e l h e a d  9^essive  contests a  n  d  90. During did  coho.  winter,  Behavior  w h i c h were  evident  infrequently  adaptive  predation. subject or  stones,  (1955b) has  on  parr  trout  demonstrated and  chased  under the fish  stones  from  near  the  the  large  of  The  young  from winter  freshets  distributed  along  easily birds  the  of  can  see  I t may  frequently  take  a heavy  i n open  searched  to  water  that  considerable  cm  in  trout  stones  i t offers  rather important  protection  fish  otherwise  in  diameter.  shelter is  many  toll  actively  assumed  gain  t o 40  because  jams  (1959)  fish  be  seeking  stream margins-in  and  cases h i d i n g  20  from predation  conditions  position.  d o w n among t h e  habit  exhibited  either in log  even  I n most  steelhead  and  are  Bergstrom  stones would  found w e l l  surface.  ecology  and  were under r o c k s  were  as  displays)  "scouring"  Columbia  parr.  such predation.  fish  from  mergansers  The  wag  under w i n t e r  i n maintaining  could  wig  groups  coho were  behavior,  Lindroth  trout  and  of  trout  them  hiding  mergansers  under  nips  in tight  trout.  British  shown t h a t  Chilliwack River  than  of  hence,  f o r the  in positions  Many h i d i n g  in  rivers  populations. that  of  shown by  them t e n a c i o u s l y .  protection the  groups  i s advantageous  Lindroth  occur  (threat  in protecting  freshets;  not  group behavior  behavior  Coastal  to  under  i n the  value  did  components  i n laboratory  Hiding has  trout  which  are  unprotected  locations. The in  the  foregoing  behavior  and  comments h a v e p o i n t e d  ecology  occupy  a wider v a r i e t y of  in  the  largest  in  space  stream) the  utilization.  The  of  the  two  species.  stream h a b i t a t s two  species  out  than  overlap  r e l a t i o n s h i p of  some  differences  Although coho to  similar  trout  (particularly  a large species  degree such  91. as  the trout  and  coho m a k i n g  to  a fundamental  B.  I n t e r a c t i o n o f Young  interest  Segregation trout  occurred  greatest in  experiments  was  use  were  highest  by t h r e e  may  have  and  have In  pools.  winter  summer  ( F i g .16).  Second, stream  ( F i g .38).  substantially  and  These  to the winter  three  demands,  d e n s i t i e s were of  aggressiveness  and of  this  chasing.  Size  segregation.  summer  ( F i g . 17)  pools. situation,  extent  i n the  interspecific  different  d e n s i t i e s were  lower  of aggressiveness f a c t o r s must  coexistence  winter  and p r e f e r e n c e s  a q u a r i u m , were  Third, levels  occurred  In addition to  distribution  population  that  similar  factors contributed to t h i s spatial  two  segregated  Levels  ( F i g .38).  from  and  when  These  and t r o u t c o e x i s t e d t o a l a r g e  species, i n the stream  winter  Population  the trout i n spring  First,  ( F i g .16),  i n  had  o p p o s i t i o n t o t h e above  o f coho  Three main  winter.  months,  I n t e r a c t i o n , which species  factors.  coho  Separation  the b e l i e f  be m a n i f e s t e d  d i s p l a c e d them  direct  compatability. two  winter  contributed to the effect  l a r g e r than  populations  preferences.  shown i n v o l v e d much b i t i n g  Coho were  in  may  e a r l y i n the year  aggressiveness  could  o f young  experiments i n d i c a t e d  support  ( N i l s s o n 1956, 1963).  i n s p r i n g and  differences  the  together  competition  accentuated  highest  Coho  pronounced during  s p r i n g a n d summer b e c a u s e b o t h  was  the  and  of environmental  considered  interspecific  in  Steelhead  of n a t u r a l populations  least  leads  eco-biology.  indicated differences i n preferences.  observations  resource  i n  at the season i n which  similarity  the w i l d  d e m a n d s o n t h e same r e s o u r c e  o f coho  were  i n in lower  contribute and  of  trout.  92. There  i s an a p p a r e n t  paradox  i n the fact  populations  o f both  experiments  indicate differences i n preferences.  pointed the to  out therefore, that  deepest a pool  space and  (Fig. 26).  differently,  trout  space  beside  of  a stream  coho  formed  during  However  and c o v e r  coexistence  of both  other.  As a l r e a d y  because  levels  groups  small  such  space  under  both  as t h o s e  s t a t e d , such  this  above  b u t coho (Figs.  may m a k e  27  bottom, In the occupied and'28).  a demand o n  could  permit  w i t h i n a few inches  i n both  pool  d i f f e r e n c e s i n the use  coexistence  of aggressiveness  comparable  31 and 3 2 ) .  from them  described,  i n a pool  be  a preference f o r  stones  species  when  I t should  i n open w a t e r  but important  species  showed  (Figs.  wild  at a season  and coho u t i l i z e d  or downstream  the winter  pools  g r a d i e n t , w h i c h was  the bottom  t r o u t occupied  the stones  space.  space  species  However t r o u t  scattered across  gradient  pool  both  s e c t i o n of the depth  cover  In  t r o u t and coho o c c u p y  that  would  species  be  of each  facilitated  are low during  winter. The why  coho  occur  and t r o u t  together  remains. two  How  discussion explains  segregate  i n winter. do t h e s e  distinctive  gain  induced  visual  to take  reference  of this  i n spring  one i m p o r t a n t remain  problem  of environment  Hartman  reference  However  some o f t h e r e a s o n s  points.  To  o f young  brown t r o u t  positions i fpresented  the rate  still  be v a l u a b l e t o  on t h e b e h a v i o r  I f the structural  p o i n t s was i n c r e a s e d ,  question  and pools'?  i t may  (1963) showed t h a t young  up a n d d e f e n d  a n d summer b u t  i n equilibrium i nthe  natural microhabitats, r i f f l e s  the effect  brown t r o u t .  spatially  two s p e c i e s  better understanding  consider  be  previous  complexity  of occupancy  could  with of  was  simple  these  93. increased.  K a l l e b e r g (1958) showed t h a t t h e  territories  by  running  young  water.  released  by  reinforced  Territorial  certain by  brown t r o u t  territories  appears  governed  a complex  by  steelhead  i n the  The  t o be of  riffle  i n the  to  defend  space  differential by  the  (Fig.  it  and  one  for.this  thus  be  l e s s , so  i n the  relationship  in riffles.  differential able to  shifting  the  than  conditions i s and  motivated a  indicated  pool  habitats  probably  whole  If  displaced  smaller trout  i n the  of  stream.  a g g r e s s i v e n e s s , coho  balance,  which they  i n motivational states  e l i m i n a t e the  young  to various  Such  t h r e e m i c r o - h a b i t a t s of the  social  concluding the of  these  behavior  two  comments on  stream,  account,  i n a large  of  in  environments  riffle  and  pool  equilibrium  of  interaction.  coho  the  from  the  i n favor  ecological  species i t i s emphasized  change i n s e v e r i t y  the  stimuli  strongly  in riffle  is  Presumably  coho  Salmon R i v e r i s  differences  defending  defence,  of young  environmental  be  species. In  in  of  stimuli.  territory  i n aggressiveness  coho i n t h e  pools would  riffles, of  because  were not  from  to  Segregation  maintained trout  response  and  r e c e i v e d more  responses  and  could  was.  of behavior which  h e n c e , t h e y were more  i n pools  differences 42).  The  and  by  brown t r o u t  of which  type  of  initiated  choosing  environmental  received  different;  of  a reactive  aggressive behavior  were  of young  effect  behavior  elicited  stimuli  the  environment  pools.  s a l m o n was  behavior  stimuli,  others.  and  defence  and  way,  Differences in  account  trout  f o r the  i n the  f o r the  that  changes  seasonal aggressiveness  segregation  two m i c r o h a b i t a t s ,  and  94. C.  C o m m e n t s on A  which in  Concepts  number o f  competition  segregation  and  Connell,  fish  has  Muira  (see  Beaucharnp  and  Saunders  competing  species  preceding  cases  physiological of  the  similar,  of  of  Gee  1958,  stream species  environment.  has  a  slight  advantage  segregate  out  indicate 1963).  i n homogeneous  otherwise Grinnell  (1963) have occur  controlled  (reviews (1904),  Gause  indicated that  together  without  (1955a),  one  the to  Aphytis  eliminates.another  above  illustrates  species  with  They  stated  and  competitive  because  "the  that  point  1947;  and  displacement  of  the  of  out  that  competition, would  Bach  Bach  and  and  Sundby  same n i c h e  other. one  cannot  cannot  Bach  species  of  been  a  mentioned  hypothesis", i.e. coexist long  way.'the h y p o t h e s i s  has  and  d i s p l a c e d by  displacement  displacement  De  Sundby,  has  in  been  variations in i t s interpretation, concept  the  i n some  de  the  i n which  e c o l o g i c a l niches  the  De  having  the  Kalleberg  I n most of  other  i s subsequently  competitive  Because of  and  suggest  identical  same h a b i t a t .  a case  in  come i n t o e q u i l i b r i u m  e l i m i n a t i n g the  (1963) have r e c o r d e d  species.  (1934)  1963).  segregation  environments,  Crombie,  species  Sundby  third  by  and  among  morphological,  over  and  1961;  i t occurred  salmonids.  I t i s necessary  species  1960  Lindroth  dwelling  Macan,  n a t u r e , s i n c e many l a b o r a t o r y i n v e s t i g a t i o n s on  carried  the  (1955,  in  manifested  competition  (1964) d e a l w i t h  behavioral  competing  by  several cases'in which  and  is  1932;  produced  fish.  instances  species  Ullyott,  Nilsson  Japanese  each  or  by  between  and  Segregation  (1962) r e v i e w e d  (1958)  in  interaction  1961).  species  Competition  i n v e s t i g a t o r s have r e p o r t e d  been r e c o r d e d  competing  part  or  of  the  c o n t r o v e r s i a l (Hardin,  95. 1960; The  Cole,  1960;  Patten,  concept might  have  1961;  Van  been more  Valen,  1960;  acceptable  Mcintosh,  i f i t had  1961).  stated  L  that  - i n admpatric  competitive  interaction  ecological  and  difficulty  of  although  how  the  and  their  niche,  the  and  Bach  occupying the  necessary  control to  the  degree  of  displacement gradient or  the  need  the  of  These or  be  of  coho  true  not  lead to  identical  are  of  segregation  be  thus,  such  to  say  competition  may  of  fish  and  an  are  hence  i n the  animal in  alter  do.  old  in  general  can  presumed to  as  This,  freshwater  w h e n no  will  one  species. as  determine  the  type  species. of  end  is  factors reasonable  as  the  effects in  habits, separation  c o n d i t i o n s , changes one  species  It is well  wasps  of  additional  involve displacement  i n food  e l i m i n a t i o n of  parasitic  incapable  e l i m i n a t i o n of  specialization  may  the  virtually  competing  i n one  niches,  quantifying  niche  fish  the-  (1959).  species  effects  the  1956)  animals  amount o f  manifested  with  freshwater  competition  both  environmental  complete  not  be  niche;  of  or  (Larkin,  specialized  similarity  competition.  manifest,  Fryer  of  does  of  of  because  not  numbers o f  assume t h a t  problem  degree  be  t r o u t and  outcome  This  level  I t i s Impossible  flexible  altered  the  the  similarity.  S u n d b y , 1 9 6 3 ) , may  an  species  species  growth r a t e  s t u d i e d by  and  the  Temperate  young  Highly (De  will  h a n d , may  environments  similarity.  behavioral  as  other  similar  increase with  leave  habitat.  unspecialized  on  still  numbers, the  a particular  of  discussing different  such i n t e r a c t i o n  alter  will  behavioral  i t does  ecological  populations  of  space, i n some  i n growth r a t e s , Species  result  interaction  only.  96:. In postulated  the f i e l d  of ecology,  much more e a s i l y  they  research  forward  by N i l s s o n (1956 and 1963) a p p l y  it  demonstrate  framework  laboratory.  for  the concept a particular  addition, ecological a  that  such  for interpreting  the  of  not demonstrate  Moreover that  certain  relationships  provide  situations  the role  o f t h e two s p e c i e s  show.  put although  a valuable i n nature  further  t o be s e g r e g a t e d  s t r o n g b e h a v i o r a l b a s i s f o r the marked  they  i n a l l cases,  when i t i s i n s h o r t  has emphasized  The  that the concepts  t h e work p r o v i d e s  species tend  resource  the study  concepts  c a n o f t e n be  c a n . be t e s t e d - .  present  does  does  than  hypotheses  support i n their  supply.  i n the  demonstrated  segregation  use  In  of behavior and  and i n  which  97. LITERATURE  CITED  B e a u c h a m p , R.S.  a n d P. U l l y o t t . ' 1 9 3 2 . C o m p e t i t i v e r e l a t i o n s h i p s between c e r t a i n s p e c i e s o f f r e s h - w a t e r t r i c l a d s . J . E c o l . 20 ( 1 ) : 2 0 0 - 2 0 8 .  C h a p m a n , D.W,  1962, A g g r e s s i v e , b e h a v i o r o f j u v e n i l e coho salmon as a cause o f e m i g r a t i o n . J . F i s h . Res. Bd. C a n a d a , 19(6): 1 0 4 7 - 1 0 8 0 .  Cole,  L.C.  1960. C o m p e t i t i v e 348-349.  exclusion.  Science',  132  (3423):  Connell,  J.H.  1 9 6 1 . The i n f l u e n c e o f i n t e r s p e c i f i c c o m p e t i t i o n and o t h e r . f a c t o r s on t h e d i s t r i b u t i o n o f t h e barancle Chthamalus s t e l l a t u s . Ecology,, 42(4): 710-723.  Crombie,  A.C.  1947. 16(1):  De  B a c h , P.  Fabricius,  G.  Gause,  G.F.  J . Animal  Ecol..  1 9 5 3 . A q u a r i u m o b s e r v a t i o n s on t h e s p a w n i n g b e h a v i o u r o f t h e c h a r , Salmo a l p i n u s . R e p t . F r e s h w a t e r Res. D r o t t n i n g h o l m , 34: 14-48.  Inst.  1 9 5 9 , The t r o p h i c i n t e r r e l a t i o n s h i p s a n d e c o l o g y o f some l i t t o r a l c o m m u n i t i e s o f L a k e N y a s a w i t h e s p e c i a l r e f e r e n c e t o t h e f i s h e s , and a d i s c u s s i o n of the e v o l u t i o n of a group of r o c k - f r e q u e n t i n g C i c h l i d a e . Proc. Zool. Soc. London,132(2):153-281.  Grinnell,  1 9 3 4 . The s t r u g g l e f o r e x i s t e n c e . Wilki.ns Co., B a l t i m o r e . 163 p.  The W i l l i a m s  J . \ 1904.' T h e o r i g i n a n d d i s t r i b u t i o n o f t h e backed chickadee. Auk, 21: 364-382.  H a r d i n , . G.  Hartman,  competition.  a n d R.A, S u n d b y . 1963. C o m p e t i t i v e displacement between e c o l o g i c a l homologues. Hilgardia,- 34(5): 105-166. E.  Fryer,  Interspecific 44-73.  1960. 131  G.F.  The c o m p e t i t i v e e x c l u s i o n p r i n c i p l e . (3409): 1292-1297.  and  chestnutScience,  1 9 6 3 . O b s e r v a t i o n s on b e h a v i o r o f j u v e n i l e brown t r o u t i n a s t r e a m a q u a r i u m d u r i n g w i n t e r and s p r i n g . J . F i s h . R e s . Bd. Canada, 2 0 ( 3 ) : 769-787.  98. Kalleberg,  Keenleyside,  Larkin,  1958. Observations i n a stream tank of t e r r i t o r i a l i t y and c o m p e t i t i o n i n j u v e n i l e salmon a n d t r o u t ( S a l m o s a l a r L . a n d S. t r u t t a L . ) . R e p t . I n s t . Freshwater Res. D r o t t n i n g h o l m , 39:55-98.  H.  M.H. a n d F.T. Y a m a m o t o . 1962. T e r r i t o r i a l behaviour of j u v e n i l e A t l a n t i c s a l m o n (Salmo s a l a r L. ). B e h a v i o u r , 19 ( 1 - 2 ) : 1 3 9 - 1 6 9 . 1956. I n t e r s p e c i f i c c o m p e t i t i o n and p o p u l a t i o n control i n freshwater f i s h . J . F i s h . Res. Bd. Canada, 1 3 ( 3 ) : 327-342.  P.A.  Lindroth,  A.  1955a. D i s t r i b u t i o n t e r r i t o r i a l b e h a v i o u r and movements o f s e a t r o u t f r y i n t h e R i v e r I n s a l s f i l v e n . Rept. I n s t . Freshwater Res. D r o t t n i n g h o l m , 36:104119.  ,  1955b, M e r g a n s e r s as salmon and t r o u t p r e d a t o r s i n the R i v e r I n d a l s & l v e n , Rept. I n s t . Freshwater Res. D r o t t n i n g h o l m , 36: 126-132.  , and E. B e r g s t r B m . 1959. N o t e s on t h e f e e d i n g technique of the goosander i n streams. Rept. Freshwater Res. D r o t t n i n g h o l m , 40: 165-175. Macan,  T.T.  Mcintosh, Milne,  A.  M i u r a , ' T,.  1961. F a c t o r s t h a t l i m i t the range o f animals. B i o l . Rev. 36: 151-198.  R.P,  freshwater  exclusion principle.  Science,  1 9 6 1 . D e f i n i t i o n o f c o m p e t i t i o n among a n i m a l s . Symposia, Soc. E x p t l . B i o l . 15: 40-61. 1962. E a r l y l i f e h i s t o r y and p o s s i b l e i n t e r a c t i o n o f f i v e i n s h o r e species o f f i s h i n N i c o l a Lake, B r i t i s h 'Columbia. Ph.D. T h e s i s , D e p t . Z o o l . U n i v . B r i t i s h C o l u m b i a , .133 p .  Newman, M.A. Nilsson,  1961. Competitive 133(3450): 391.  Inst.  1956. Social i n two t r o u t  N.A.  »  b e h a v i o r and i n t e r s p e c i f i c c o m p e t i t i o n species. Physiol. Zofll. 29(l):64-81.  1955. S t u d i e s on t h e f e e d i n g h a b i t s o f t r o u t char i n North Swedish l a k e s . Rept. I n s t . F r e s h w a t e r Res. D r o t t n i n g h o l m , 36: 163-225. 1956. 1956:  Om k o n k u r r e n s e n 40-47.  i naturen.  Zoologisk  and  Revy,  1958. On t h e f o o d c o m p e t i t i o n b e t w e e n t w o s p e c i e s of Coregonus i n a N o r t h - S w e d i s h lake. Rept. I n s t . Freshwater Res. D r o t t n i n g h o l m , 39: 146-161.  99. Nilsson,  N.A.  1960. Seasonal f l u c t u a t i o n s i n the food s e g r e g a t i o n o f t r o u t , c h a r a n d w h i t e f i s h i n 14 Swedish lakes. Rept. I n s t . Freshwater Res. D r o t t n i n g h o l m , 41: 185-205. ,  Patten,  B.C.  North-  1963. I n t e r a c t i o n between t r o u t and c h a r i n Scandinavia. T r a n s , Am. F i s h e r i e s S o c . 9 2 ( 3 ) : 276-285. 1961. Competitive 1599-1601.  exclusion.  Science,  134(3490)  S a u n d e r s , R.L,  and J.H. Gee. 1964. Movements o f young A t l a n t i c Salmon i n a s m a l l stream. J . F i s h . R e s . Bd. Canada, 2 l ( l ) : 27-36.  Van  1960. Further competitive 132(3440): 1674-1675.  Valen,  L.  Water Resources  exclusion.  Science,  P a p e r No. 1 2 8 . 1958-1959. Dept. North. A f f a i r s and N a t u r a l R e s o u r c e s , W a t e r R e s o u r c e s Branch. Surface Water Supply o f Canada, P a c i f i c Drainage. 388 p. No.131. 1959-1960. Dept. North. A f f a i r s and N a t u r a l R e s o u r c e s , W a t e r R e s o u r c e s Branch, S u r f a c e Water Supply o f Canada, P a c i f i c Drainage. 4 0 2 p.  Appendix  I.  Mean m o n t h l y d i s c h a r g e i n M per second, f o r the C h i l l i w a c k R i v e r at Vedder . C r o s s i n g , t h e A l o u e t t e R i v e r a t 1 4 t h S t r e e t b r i d g e and f o r t h e S a l m o n R i v e r at S p r i n g b r o o k Road b r i d g e (1958 t o 1 9 6 2 ) , J  Feb.  Mar,  Apr.  May  June  52.1 32.3 37.6 75.0 70.5  40.5 32.8 22.2 47.0 22.9  46.7 72.2 47.3 55.2 57.6  130. 5 91. 4 ..65.•4 81. 4 —  7,9 0.6  0.0 0.0  0.0 0.0  9,8. 5.2  5.2 2.2  3.1 1.1-  0.0 0.0 2.3 1.6 . 1.5..  -  Jan. 1  Chilliwack  1958 1959 1960 1961 1962 Salmon  Auq.  Sept.  Oct.  Nov.  Dec.  103.9 135.5 105.3 183.7  45.3 110.4 73.9 95.4  25.4 43.5 35.1 57.7  34.2 68.8 28.0 27.8  65.4 74.2 36.8 49.8  70.8 82.7 56.3 45.6  95.7 48.9 62.0 44.2  .—  —  1-  R..  1958 1959 1960 1961 1962 Alouette  July  56.9 70.5 22.7 73.9 88.9  —  —  —  —  -  0.0 2.2 0.6 0.3  0.0 2.2 0.7 0.4  0.0 0.0 1.9 2.1  2.0 0.0 2.4 3.5  1.4 0.0 2.1 7.0  —  —  —  —  —  —  —  _  R. "  -  -  -  0. 0 0. 0 1. 7 ' 1. 3  0.3 0.0 1.1 0.6 —  3.7 10.5 0.4 0.4 —  R.  1958 1959 I960 1961 1962  -  -. -  -  .,5.10 4.67 3.51  3.20 5.97 1.98  1.40 3.70 1.50  -  1.40 1.47 1.61  1. 4 0 1. 27 1. 34  .50 .33 .54  *.28 *.14 .28 .33 .24  *.40 *.23 *.38 . *.31 .27 .23 .25 .21 .29 .33  -'  1.50 .86 .94  ±1-. 64 2.70 1.67 3.26  1 9 5 8 - 5 9 A l o u e t t e R i v e r d a t a f r o m B.C. Hydro & Power A u t h o r i t y - see * M i s c . s i n g l e r e a d i n g s Water R e s o u r c e s D i v i s i o n . + A v e r a g e o f two e s t i m a t e s by a u t h o r .  —  3.14 3,40 3.93 text.  Appendix  I I . M a x i m u m , m i n i m u m a n d m e a n m o n t h l y t e m p e r a t u r e (°C) o f t h e C h i l l i w a c k R i v e r , (*mean b a s e d o n l e s s t h a n 20 day's d a t a , * * m e a n b a s e d o n l e s s t h a n 1 0 d a y s d a t a ) .  1  9  6  0  1  9  6  1  1  Max.  Min.  Mean  Max.  Min.  Mean  5.9  -2.0  2.8  6.0  2.0  February  6.0  -2.0  4.2*  5.2  March  8.0  -1.0  4.3  April  10.1  4.3  6.2  May  10.3  5.9  7.5*  June  12.0  5.8  July  17.0  January  August  ~  •  17.5  Mean  4.2  3.7  -1.0  2.0  3.0  4.1*  5.0  -1.0  2.3**  2.0  3.6*  7.5  -0.5  3.0  8.8  2.5  5.9  11.5  2.0  6.2  10.6  4.5  6.9  11.7  5.5  8.1  8.6  12,2  6.5  9.3  8.4  12.4  15.8  8.2  11.9  10.0  13.0  16.0  9.0  13.0  .  .  6.0  -  -  10.0  5.5  7.5*  6.2  4.1  -1.0  2.4*  4,8  4.0  0.0  9.0  11.2  -  October  12.1  6.6  9.1  8.1  4.5 '3.4  ~6.0  2  Min.  13.8  December  6  Max.  September  November  9  2.2  Appendix  I I I . M a x i m u m , m i n i m u m a n d mean m o n t h l y t e m p e r a t u r e (°C) o f t h e A l o u e t t e R i v e r , • .(*mean b a s e d o n l e s s t h a n 20 d a y s d a t a , * * b a s e d o n l e s s t h a n 10 d a y s d a t a ) .  1 Max.  9  6 Min.  0  1 Mean  9  Max.  6 Min.  1  1 Mean  6.5  0.0  2.8  4.2  6.1*  1.5  5.5  5.2 '  8.9  February  7.2  1.7  5.4*  March  10.3  5.0  6.3*  10.6  April  11.1  5.0  8.4*  13.4  May  20.5  6.1  4.2* •  2  Min.  6.4  0.7  6  Max.  January  •  9  7.4  '  Mean  12.0  • 15.0  6.9  10.5  .; 2 0 . 6  9.6  14.3  June  23.4  10.5  15.2*  25.0  11.2  17.8*  July  27.8  ..1.2.8  20.8*  27.1  13.1  20.1  August  27.8  12.2  15.6*  23.8  12.1  18.0**  September  13.7  10.0  11.3**  15.0  11.1  13.2**  October  11.6  6.6  9.1  15.0  3.4  10.2**  November  8.8  2.1  5.3  5.5  4.5/  5.2**  December  6.1  0.0  2.5  5.0  3.0  4.0**  Appendix  IV.  Maximum,  1  9  m i n i m u m a n d mean m o n t h l y  temperature  6  9  0  1  6  2  3.7  6.4  0.0  3.2  3.6  5.5.  9.2  -0.5  5.4  10.3  3.1  "6.8  10.3  0.3  5.0  7.2  0.6  February  7.8  March  6  Mean  January  Mean  9  Min.  Min.  Min.  1  1  River.  Max.  Max.  Max.  (°C) o f t h e ' S a l m o n  Mean--  April  11.7  5.0  8.1  11.7  5.9  8.7  14.7  5.9  9.5  May  11.7  7.2  9.0  15.3  8.6  11.2  14.2  7.3  10.6  June  13.4  8.6  10.8  . 17.5  11.4  14.0  17.8  9.5  12.9  July  16.4  10.0  '13.0  20.3  10.0  15.5  August  17.0  9.2  12.1  10.0  15.2  September  13.1  8.9  11.2  15.9  8.6  11.7  October  12.0  7.2  9.5 "  12.2  5.6  8.7  November  9.2  3.9  6.4  8.4  2.8  5.3 •  December  7.6  0.6  3.8  6.7  1.1  3.7  •  18.4  A p p e n d i x V, M e a n f o r k l e n g t h a n d r a n g e o f s a m p l e s o f f i s h u s e d i n e x p e r i m e n t s , O c t o b e r 1 9 6 2 t o N o v e m b e r 2 3 , 1 9 6 3 . (* - m e a s u r e m e n t s made o n p r e s e r v e d m a t e r i a l ) . C o h o - C, S t e e l h e a d - S.  Date p r e s e r v e d or measured Oct.  19-20, 1962  Jan.  10,  Jan.  May May  ii  25,  J u n e 8, " June 12, " July  II  Sept.  ti  Oct.  19, " II  2,  II  8, II  Nov.23,  ti  " "  tt 1963  ti  Range in mm..  Sample Size.  73 40  66.2 61.7  47- -88 47- -76  40 40  II  c s  67.5 59.3  51- -99 49- -67  57 40  1963  C  s  37.9 33.5  35-42 26-42  15 22  ti ti  n ii  c s  43.4 39.7  40-47 29-49  16 62  ii ii  ti ii  c s  52.1 42.7  38-64 35-56  65 64  ti ii ti  c s  66.4 56.2  50-89 39-80  60 74  ti ii  ti ti ti ti  c s  73.1 72.7  52-104 54-102  65 36  n  II  II  II  II  II  c s  76.7 73.2  62-93 47-112  30 35  it  C S  II  II  •i  II  II  II  ti  c  II  S  n n  c s  u n  n  7 t o Nov.23,  II  II  II  II  II  May  Mean F o r k L>.. r inl'ram'.:  52- -97 50- -75  1962- F e b . 2 0 , 1 9 6 3  n  1, 1963 25, "  Species  13 20  II  ti  when u s e d  ' 4 0 --95 38- -72  Nov.1,  1963  19,  April  Period  n II  ti II  ti II II  II  II  II  58.3 50.9 68.6 • 60,7  '  30,  -*  * -* #•  -* -*  * *  Appendix  Date  V I . D e t a i l s o f s p r i n g a n d e a r l y summer e x p e r i m e n t s c o m p a r i n g b e h a v i o r d i s t r i b u t i o n o f coho and s t e e l h e a d .  and Y e a r  Arrangement i n Aquarium  Species. (40 f i s h )  Temperature Range °C  Day L e n g t h i n H o l d i n g Pond  and  A v e r a g e number moving  1963 April "  12  1.8  8.5-9.2  12  2.7  11.7-12.0°  12  3.9  14.0-14.3°  12  6.0  10.0-11.2  12  3.7  Steelhead  13.0-13.3  12  2.2  Coho  13.0-13.5  12 '  4.1  Control  21-23  it  it  II  it  II  Steelhead  June  7-9  "  9-11  May  26-28  Cover  28-30  II  "  6.5-8.3  Coho  19-21  June' 11-13  Light  Coho  13-15  n  Steelhead  13.4-14.0  12  1.9  22-24  Depth  Steelhead  15.2-15.6  12  4.8  24-26  it  Coho  14.0-15.9  12  4.1  June 30July 2  Depth & Velocity  Steelhead  14.0-14.5  12  9.8  July  it  11  June "  April " June  2-4 28-30 • 24-26 16-18  ti  Coho  14.9-15.4  12  8.4  Cover  Coho  it Depth  7.1-7.5  12  2.5  II  7.1-8.4  12  1.1  II  15.0-16.0  12  3.5  1--  o  (Jl  Appendix V I I ,  D e t a i l s of f a l l experiments comparing behavior s t e e l h e a d and coho.  and d i s t r i b u t i o n  of  young  Arrangement i n Aquarium  Species (40 f i s h )  Temperature Range °C  19-21  Control  Steelhead  12.7-13.3  12  7.9  "  21-23  II  13.2- 13.4  12  3.0  Sept.  27-29  Cover  12.3- 13.1  12  11.5  Coho  14.2-14.5  12  2.6  Coho  12.7-13.5  12  3.5  13.6-14.2  12  11.6  12.5- 13.0  12  3.9  11.6- 12.1  12  7.2  Date  and Y e a r  Day L e n g t h i n H o l d i n g Pond  A v e r a g e number moving  1963 Sept.  Sept. 29Oct. 1 Sept.  23-25  11  25-27  Oct. " Oct.  •i  1-3  Light  7_9  Steelhead  Steelhead Depth  Coho Steelhead  3-5 5-7  Coho  Depth & Velocity  Coho Steelhead  10.1-10.6 10.8-11.0  12 12  6.2 7.5  Appendix  Date  VIII.  D e t a i l s of w i n t e r experiments comparing d i s t r i b u t i o n s t e e l h e a d and coho.  Arrangement i n Aquarium  and Year  Species (40 f i s h )  Temperature Range °JC  and b e h a v i o r  Cay L e n g t h i n H o l d i n g Pond  of  A v e r a g e number moving  1962-1963 Nov. II  5-7  Control  19-21  '•  Dec.  4-6  Nov. "  11-13 17-19  Dec.  11  •  •  6-8 "  Nov.30-Dec.2 Dec.  2-4  Coho  6.9-7.1 7.2-7.8  12 9  "  4.7-4.9  8 12 12  18.3 17.7  8.7 6.3  Control "  Steelhead «  7.0-7.1 6.2-7.2  "  "  5 . 2 - 5.7  8  19.7  2 . 7 -3.2  9  2.2  ,3.1-4.0  9  7.4  5.0-5.3  8  . 5 . 0  5 . 3 - 5.6  8  10.6  2.0-2.4 2 . 4 - 2.8  8 8  1.1 2.1  3.0-3.1 2 . 8 - 2.8  8 8  7.0 8.1  1.7-2.5 0.5-1.0  8 8  2.3 0.6  3 . 9 - 4.4 0.8-1.0  8 8  0.7 0.9  Light Light  Coho Steelhead  i  Dec.17-19  Depth & V e l o c i t y  Dec.19-21  Depth & V e l o c i t y  Jan.19-21 " 23-25  Cover "  Jan.21-23 " 25-27  Cover "  Jan.  Depth "  II  1 2  8-10 _14  J a n . 6-8 " 10-12  Depth 11  Coho Steelhead Coho 11  Steelhead " Coho Steelhead "  young  

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