UBC Theses and Dissertations

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UBC Theses and Dissertations

Distribution and habitat responses of the coastrange sculpin (Cottus aleuticus) and prickly sculpin (Cottus… Taylor, Gerald David 1966

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D I S T R I B U T I O N A N D H A B I T A T R E S P O N S E S O F T H E C O A S T R A N G E S C U L P I N ( C o t t u s a l e u t i c u s ) A N D P R I C K L Y S C U L P I N ( C o t t u s a s p e r ) I N T H E L I T T L E C A M P B E L L R I V E R , B R I T I S H C O L U M B I A b y G E R A L D D A V I D T A Y L O R B . S c , U n i v e r s i t y of B r i t i s h C o l u m b i a , 1963 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 O F T H E R E Q U I R E M E N T S F O R T H E D E G R E E O F M A S T E R O F S C I E N C E i n t h e D e p a r t m e n t of Z6ology W e 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 r e q u i r e d s t a n d a r d T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A D E C E M B E R 1966 In presenting this thesis i n p a r t i a l fulfilment of the requirements for an advanced degree at the University of Bri t i s h Columbia,, I agree that the Library shall make i t freely available for reference and study* I further agree that permission.-for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives„ It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. , . ^ ZOOLOGY Department of The University of B r i t i s h Columbia Vancouver 8, Canada ^ . December, 1966 Date i i A B S T R A C T D i f f e r e n t i a l r e s p o n s e s t o w a t e r c u r r e n t a n d s u b s t r a t e , e x h i b i t e d b y p o p u l a t i o n s o f C o t t u s a l e u t i c u s a n d C o t t u s a s p e r i n t h e L i t t l e C a m p b e l l R i v e r , w e r e s t u d i e d b o t h i n t h e f i e l d a n d i n e x p e r i m e n t a l l a b o r a t o r y a p p a r a t u s . . B o t h b r o a d - s c a l e a n d l o c a l d i s t r i b u t i o n s o f C . a l e u t i c u s a n d C . a s p e r a p p e a r t o b e c l o s e l y a s s o c i a t e d w i t h a v a i l a b l e h a b i t a t . T h e s l o w m o v i n g a r e a s of t h e l o w e r r i v e r a p p e a r t o p r o v i d e a d e q u a t e h a b i t a t f o r f r y of b o t h s p e c i e s . T h e s e f i s h h a v e the l e a s t d e c i d e d p r e f e r e n c e s f o r c u r r e n t a n d s u b s t r a t e c o n d i t i o n s . A s y e a r l i n g s t h e t w o s p e c i e s s h o w a l m o s t c o m p l e t e d i v e r g e n c e of h a b i t a t c h o i c e w i t h m o s t C . a s p e r i n h a b i t i n g s l o w a r e a s of t h e l o w e r r i v e r a n d m o s t C . a l e u t i c u s m o v i n g u p s t r e a m t o r i f f l e s a n d o t h e r a r e a s of d i s t i n c t c u r r e n t . A s a d u l t s , C . a s p e r i n h a b i t a r e a s of n o n - c u r r e n t , d e c r e a s i n g i n n u m b e r s f r o m m o u t h t o s o u r c e of t h e s t r e a m , c o i n c i d e n t w i t h a d e c r e a s e i n o c c u r r e n c e of p o o l e n v i r o n m e n t s . T h e u p p e r r i v e r , w h i c h i s e n t i r e l y p o o l h a b i t a t , m a y h a v e a r e d u c e d C . a s p e r p o p u l a t i o n d u e t o i s o l a t i o n f o r s i x m o n t h s of t h e y e a r a n d s u s p e c t e d l o w o x y g e n c o n c e n t r a -t i o n s . C o t t u s a l e u t i c u s y e a r l i n g s a n d a d u l t s a r e f o u n d p r i n c i p a l l y i n t h e m i d d l e r i v e r w h e r e a r e a s of c u r r e n t a r e p r e s e n t . D a y a n d n i g h t c o l l e c t i o n s r e v e a l t h a t y e a r l i n g a n d a d u l t C .  a l e u t i c u s a n d a d u l t C . a s p e r a r e l a r g e l y s e g r e g a t e d i n t o d i f f e r e n t m i c r o h a b i t a t s d u r i n g d a y l i g h t b u t m a y o c c u p y s i m i l a r a r e a s d u r i n g d a r k n e s s . F o r m a t i o n of p o o l e n v i r o n m e n t s b y t i d a l i n u n d a t i o n o f f o r m e r c u r r e n t and non-current areas appears to allow f r y of both species, p r e v i o u s l y l a r g e l y segregated, to occupy s i m i l a r a r e a s r e g a r d l e s s of time of day. Both species were found to feed p r i n c i p a l l y at night as y e a r l i n g s and adults. Responses of f i e l d f i s h d i s p l a c e d to habitats not n o r m a l l y occupied strongly suggests the importance of environmental f a c t o r s i n determining d i s t r i b u t i o n and abundance and, in segregating the two species under n a t u r a l conditions. F i s h were given a choice of c u r r e n t and non-current areas i n one s e r i e s of l a b o r a t o r y experiments and c o a r s e and fine substrates i n another s e r i e s . T e s t s were p e r f o r m e d on f i s h taken d i r e c t l y f r o m the f i e l d , on f i s h h e l d i n bare hatchery troughs f o r 60 days, and on f i s h exposed to simulated n a t u r a l conditions of flow and substrate f o r 60 days. At c u r r e n t speeds of 45 c e n t i m e t e r s p e r second, C. aleuticus f r y (less than 40 m i l l i -m e t e rs) in the l a b o r a t o r y showed no p r e f e r e n c e f o r either c u r r e n t or non-c u r r e n t a r e a s , while f i s h g r e a t e r than 60 m i l l i m e t e r s (y e a r l i n g s and adults) tended to select current. Cottus aleuticus, at a l l s i z e groups tested, p r e f e r r e d c o a r s e rather than fine-textured substrate. In the f i e l d , C. aleuticus showed a p r e f e r e n c e f o r c u r r e n t and c o a r s e substrate although f r y often occupied a r e a s of fine substrate and non-current when C. asper were absent or s c a r c e . Cottus aleuticus, as y e a r l i n g s and adults, were r a r e l y found over fine substrate. In l a b o r a t o r y experiments C. asper g e n e r a l l y p r e f e r r e d n o n-current to c u r r e n t and showed no substrate p r e f e r e n c e e x c e p t f r y w h i c h p r e f e r r e d c o a r s e s u b s t r a t e . F i s h b e t w e e n 80 a n d 100 m i l l i m e t e r s s h o w e d n o p r e f e r e n c e f o r e i t h e r c u r r e n t o r n o n - c u r r e n t a r e a s i n t h e l a b o r a t o r y . In t h e f i e l d , C . a s p e r w e r e r a r e l y a s s o c i a t e d w i t h c u r r e n t b u t w e r e f o u n d o v e r a w i d e r a n g e of f i n e a n d c o a r s e s u b s t r a t e . W h e n a c h o i c e of f l o w a n d s u b s t r a t e c o n d i t i o n s w e r e o f f e r e d s i m u l -t a n e o u s l y , _C_. a l e u t i c u s p r e f e r r e d c u r r e n t a n d c o a r s e s u b s t r a t e . C . a s p e r s h o w e d n o p r e f e r e n c e f o r e i t h e r f l o w c o n d i t i o n a n d hacl n o s u b s t r a t e p r e f e r e n c e . T h e r e w a s n o s i g n i f i c a n t d i f f e r e n c e i n a s p e c i e s r e s p o n s e to f l o w a n d s u b s t r a t e w h e n t e s t e d s i n g l y o r i n g r o u p s . H o l d i n g c o n d i t i o n s ( b a r e t r o u g h s a n d s i m u l a t e d n a t u r a l c o n d i t i o n s ) d i d n o t c h a n g e r e s p o n s e s of e i t h e r s p e c i e s f r o m t h o s e o u t l i n e d f o r f i s h t e s t e d d i r e c t l y f r o m t h e f i e l d . F i e l d a n d l a b o r a t o r y r e s u l t s s u g g e s t h a b i t a t s e g r e g a t i o n to b e m o s t p r o n o u n c e d i n f i s h b e t w e e n 40 a n d 80 m i l l i m e t e r s l o n g . T h e r e l e v a n c e of t h e s e r e s u l t s t o h a b i t a t s e g r e g a t i o n b y t h e t w o s p e c i e s i n a s t r e a m i s d i s c u s s e d . F o o d , r e p r o d u c t i o n , f i s h a s s o c i a t i o n s a n d d e n s i t i e s a r e a l s o d i s c u s s e d a s f a c t o r s a f f e c t i n g s p a t i a l a n d t e m p o r a l d i s t r i b u t i o n of t h e s p e c i e s . V T A B L E O F C O N T E N T S P a g e T I T L E P A G E i A B S T R A C T i i T A B L E O F C O N T E N T S v L I S T O F F I G U R E S v i i L I S T O F T A B L E S : x L I S T O F A P P E N D I C E S x i i I N T R O D U C T I O N 1 D E S C R I P T I O N O F S T U D Y A R E A 2 G E O G R A P H Y A N D G E O L O G Y 2 D E S C R I P T I O N O F " T H E ' S T L R E A M 2 P h y s i c a l a n d C h e m i c a l F e a t u r e s 10 B i o l o g i c a l F e a t u r e s ' 12 M E T H O D S A N D A P P A R A T U S 13 F I E L D S T U D I E S 13 R e c o r d i n g of E n v i r o n m e n t a l F e a t u r e s 13 O p e r a t i o n of D o w n s t r e a m T r a p 14 S e i n i n g P r o c e d u r e 16 S a m p l i n g S y s t e m s 16 D e s c r i p t i o n a n d M e a s u r e m e n t of V a r i a b l e s 17 D e s c r i p t i o n o f A n a l y s e s 19 P o p u l a t i o n E s t i m a t e s 20 S t o m a c h a n d I n t e s t i n a l T r a c t A n a l y s e s 20 L A B O R A T O R Y S T U D I E S 22 H o l d i n g C o n d i t i o n s 22 E x p e r i m e n t a l S t r e a m a n d T e s t S e c t i o n 24 E n v i r o n m e n t a l T e s t C o n d i t i o n s ._. 25 R E S U L T S 27 • F I E L D S T U D I E S 27 A n a l y s e s of S a m p l i n g D a t a 27 (1) 3 r o a d - s c a l e d i s t r i b u t i o n s 27 (2) L o c a l i z e d f i s h d i s t r i b u t i o n s 34 v i Page Popu l a t i o n E s t i m a t e s 38 F i s h A s s o c i a t i o n s 40 As p e c t s of D i e l and Seasonal Movement 40 L A B O R A T O R Y S T U D I E S 50 F l o w and Substrate P r e f e r e n c e s 50 (1) L a b o r a t o r y f i s h A 50 (2) L a b o r a t o r y f i s h B 54 (3) L a b o r a t o r y f i s h C 54 S U M M A R Y O F R E S U L T S 63 DISCUSSIONS 65 A C K N O W L E D G E M E N T S s 72 L I T E R A T U R E C I T E D 73 A P P E N D I X 75 v i i L I S T O F F I G U R E S 1. L o c a t i o n of L i t t l e C a m p b e l l R i v e r , W h i t e R o c k , B . C . a n d r e s e a r c h f a c i l i t i e s a t C o u r t e n a y , V a n c o u v e r I s l a n d , B . C 3 2. L o c a t i o n o f p e r m a n e n t (o) a n d t e m p o r a r y c o l l e c t i o n s t a t i o n s (o) , s t r e a m p r o f i l e a n d l i m i t s of t i d a l e f f e c t s 4 3. L o w e r e s t u a r i n e r e g i o n o f L i t t l e C a m p b e l l R i v e r . A r e a s of c u r r e n t i n f o r e g r o u n d a n d n o n - c u r r e n t i n b a c k g r o u n d at l o w t i d e ( A ) a n d - , n o n - c u r r e n t at h i g h t i d e ( B ) , J u l y , 1965 8 4. T y p i c a l l o w g r a d i e n t p o o l a n d c u r r e n t a r e a of l o w e r r i v e r . T i d a l i n f l u e n c e 0.8 m d u r i n g s u m m e r t i d e s , O c t o b e r , 1 9 6 5 . . 8 5. R i f f l e a r e a s t y p i c a l of m i d d l e r i v e r b e t w e e n S t a t i o n 9 a n d 12, O c t o b e r , 1965 9 6. R i f f l e - p o o l c o m p l e x t y p i c a l of t h e m i d d l e r i v e r , O c t o b e r , 1965 9 7. L a r g e p o o l a n d f l a t w a t e r a r e a s of u p p e r r i v e r b e t w e e n S t a t i o n 14 a n d 17, O c t o b e r , 1965 9 8. S u m m a r y of s t r e a m t e m p e r a t u r e s ( A , B ) a n d w a t e r l e v e l s ( C ) a t S t a t i o n 10, L i t t l e C a m p b e l l R i v e r . E x p e l e m e n t a l t e m p e r a t u r e s i n d i c a t e d i n B 11 9 . L e n g t h - f r e q u e n c y d i s t r i b u t i o n s ( A ) a n d n u m b e r s ( B ) o f C . a l e u t i c u s a n d C . a s p e r t a k e n i n a d o w n s t r e a m t r a p , S e c t i o n B . W a t e r l e v e l s a n d t e m p e r a t u r e s r e c o r d e d i n t r a p r e g i o n . . . . 15 10. L e n g t h - f r e q u e n c y d i s t r i b u t i o n of C . a l e u t i c u s i n p o p u l a t i o n e s t i m a t e s , J u l y 1 5 - 1 8 , 1965 , S e c t i o n s A a n d B , L i t t l e C a m p b e l l R i v e r 21 11. C o n t i n u o u s f l u m e w i t h m o d i f i e d t e s t i n g s e c t i o n i n d i c a t e d b e t w e e n p o i n t s X and> Y 23 12. A r t i f i c i a l h o l d i n g h a b i t a t s at r e s e a r c h f a c i l i t i e s , C o u r t e n a y , B . C . B a r e t r o u g h ( A ) , s u b s t r a t e a n d n o n - c u r r e n t ( B ) a n d s u b s t r a t e a n d c u r r e n t ( C ) 23 v i i i F I G U R E P a g e 13. E x p e r i m e n t a l t e s t i n g s e c t i o n of c o n t i n u o u s f l u m e w i t h s u b s t r a t e c e l l s i l l u s t r a t e d . C u r r e n t f l o w f r o m p o i n t X t o Y . . . . . . 23 14. E x p e r i m e n t a l s e c t i o n o f a c o n t i n u o u s f l u m e w i t h s u b s t r a t e c e l l s a n d f l o w c h a n n e l s i n d i c a t e d 26 15. P e r c e n t o c c u r r e n c e a n d n u m b e r ( p a r e n t h e s e s ) o f c o l l e c t i o n s i n w h i c h C . a l e u t i c u s a n d C . a s p e r w e r e f o u n d a l o n e a n d i n a s s o c i a t i o n , A u g u s t t o O c t o b e r , 1965 , L i t t l e C a m p b e l l R i v e r 41 16. A v e r a g e n u m b e r of f i s h p e r s e i n e h a u l i n a r i f f l e - r u n - f l a t -p o o l c o m p l e x , S e c t i o n C , L i t t l e C a m p b e l l R i v e r . D a t a r e p r e s e n t s 53 d a y a n d 61 n i g h t c o l l e c t i o n s t a k e n S e p t e m b e r 3 a n d O c t o b e r 10, 1965 . L i m i t s of h a b i t a t d e p t h s i n d i c a t e d i n A p p e n d i x V . A l l f i s h r e t u r n e d t o s i t e of c a p t u r e 43 17. P e r c e n t o c c u r r e n c e a n d n u m b e r ( p a r e n t h e s e s ) o f 53 d a y a n d 61 n i g h t c o l l e c t i o n s j n w h i c h C . a l e u t i c u s a n d C . a s p e r w e r e f o u n d a l o n e a n d i n a s s o c i a t i o n . D a t a c o m b i n e d f o r S e p t e m b e r 3 a n d O c t o b e r 10, 1965 45 18. T i d a l d e p t h i n f l u e n c e o n d i s t r i b u t i o n s o f C . a l e u t i c u s a n d C . a s p e r f r y , S t a t i o n 4, L i t t l e C a m p b e l l R i v e r . P e r c e n t o c c u r r e n c e of s p e c i e s i n v a r i o u s h a b i t a t s i n d i c a t e d i n p a r e n t h e s e s ; 47 19. N u m b e r a n d p o s i t i o n o f s c u l p i n s s u b s e q u e n t t o i n i t i a l r e l e a s e of 2 1 2 C . a l e u t i c u s a n d 2 4 C . a s p e r a t 0 m e t e r m a r k . A l l s a m p l e s r e m o v e d f r o m t e s t s e c t i o n o n s a m p l i n g d a t e s i n d i c a t e d . D i r e c t i o n of w a t e r f l o w f r o m +60 m t o - 6 0 m 48 2 0 . A p p r o x i m a t e p e r c e n t o c c u r r e n c e of C . a l e u t i c u s ( L a b o r a t o r y F i s h A ) i n c u r r e n t a n d n o n - c u r r e n t c h a n n e l s a n d o c c u r r e n c e o v e r c o a r s e a n d f i n e s u b s t r a t e s . T e s t s f o r f l o w a n d s u b -s t r a t e p r e f e r e n c e s p e r f o r m e d s e p a r a t e l y 51 2 1 . A p p r o x i m a t e p e r c e n t o c c u r r e n c e of C . a l e u t i c u s ( L a b o r a t o r y F i s h A ) i n c u r r e n t a n d n o n - c u r r e n t c h a n n e l s a n d o c c u r r e n c e o v e r c o a r s e a n d f i n e s u b s t r a t e s w i t h i n c h a n n e l s 1 a n d 2. T e s t s f o r f l o w a n d s u b s t r a t e p r e f e r e n c e s p e r f o r m e d s i m u l t a n e o u s l y 52 ix F I G U R E Page 22. Approximate per c e n t o c c u r r e n c e of C. as p e r ( L a b o r a t o r y F i s h A) i n .current and no n - c u r r e n t channel and o c c u r r e n c e over c o a r s e and fine substrates. T e s t s f o r flow and substrate p r e f e r e n c e s p e r f o r m e d separately 53 23. Approximate per c e n t o c c u r r e n c e of C. as p e r ( L a b o r a t o r y F i s h A) in c u r r e n t and non-current channels and o c c u r r e n c e over c o a r s e and fine substrates within channels 1 and 2. T e s t s f o r flow and substrate p r e f e r e n c e s p e r f o r m e d simultaneously 55 X I LIST O F T A B L E S T A B L E Page I. Width, depth and p o o l - r i f f l e development in different a r e a s of L i t t l e C a m p b e l l R i v e r , White Rock, B.C. Width and depths c a l c u l a t e d f r o m one year's observations; p o o l - r i f f l e r a t i o s d e t e r m i n e d f r o m May to November, 1965 5 II. E s t i m a t e d percentages of substrate types in different areas of L i t t l e C a m p b e l l R i v e r , White Rock, B.C. Relative degree of d e b r i s o v e r l y i n g substrate indicated by plus m a r k s (+) , 6 III. C o r r e l a t i o n c o e f f i c i e n t s for p a i r s of environmental v a r i a b l e s , B l o c k A n a l y s i s (broad-scale f i s h d i s t r i b u t i o n ) , 1965-1966 29 IV. C o r r e l a t i o n c o e f f i c i e n t s f o r p a i r s of environmental v a r i a b l e s , Section A n a l y s i s (local f i s h d i stribution), 1965-1966 ; 30 V. Summary of sig n i f i c a n t independent v a r i a b l e s j i n a s e r i e s of mul t i p l e r e g r e s s i o n s . Data f r o m b r o a d - s c a l e d i s t r i b u t i o n s (Block Seining), 1965-1966. Standard p a r t i a l r e g r e s s i o n c o e f f i c i e n t s are indicated and l e v e l s of signi f i c a n c e , P<0.05 (*) and P<0.01 (*#). D e s c r i p t i o n of v a r i a b l e s used i n the analyses found on pages. 28 and 32 31 VI. Summary of significant standard p a r t i a l r e g r e s s i o n c o e f f i c i e n t s f o r Section Seining and e l e c t r o - f i s h i n g data ( l o c a l f i s h d i s t r i b u -tions), Sections A and B, August to October, 1965. A s t e r i s k (*) indicated P<0.05; a l l other values P<0.01 (**). D e s c r i p t i o n of m u l t i p l e r e g r e s s i o n analyses given on page 35 37 VII. P o p u l a t i o n estimates of C. aleuticus and C. asper, Sections A and B, L i t t l e C a m p b e ll R i v e r , White Rock, B.C 39 VIII. T o t a l and approximate per c e n t o c c u r r e n c e of f i s h taken in 205 c o l l e c t i o n s containing C. aleuticus and 244 co l l e c t i o n s containing C. as p e r 42 x i T A B L E P a g e I X . S u m m a r y of a v e r a g e p e r c e n t i n t e s t i n a l t r a c t o c c u p i e d ( A ) , w e i g h t of s t o m a c h c o n t e n t s ( B ) , a n d r a t i o of s t o m a c h t o i n t e s t i n a l t r a c t w e i g h t (C) i n d a y a n d n i g h t c a p t u r e d C . a l e u t i c u s a n d C . a s p e r f r o m d i f f e r e n t h a b i t a t s i n S e c t i o n B , O c t o b e r 11 , 1965 . S a m p l e s i z e s g i v e n i n p a r e n t h e s e s . . . . 46 X . S u m m a r y of c u r r e n t a n d n o n - c u r r e n t p r e f e r e n c e s f o r L a b o r a t o r y f i s h A . R e s u l t s s u m m a r i z e d f r o m s e q u e n t i a l t e s t d e s i g n a n a l y s e s ( C o l e , 1 9 6 2 ) * . A p p r o x i m a t e p e r c e n t g i v e n i n p a r e n t h e s e s 56 X I . S u m m a r y o f c o a r s e a n d f i n e s u b s t r a t e p r e f e r e n c e s f o r L a b o r a t o r y f i s h A ( f i e l d f i s h ) . A p p r o x i m a t e p e r c e n t o c c u r r e n c e g i v e n i n p a r e n t h e s e s 57 X I I . S u m m a r y of s i m u l t a n e o u s c h o i c e of f l o w a n d s u b s t r a t e c o n d i t i o n s b y C . a l e u t i c u s a n d C . a s p e r ( L a b o r a t o r y f i s h A ) . A p p r o x i m a t e p e r c e n t o c c u r r e n c e g i v e n i n p a r e n t h e s e s 58 X I I I . S u m m a r y o f c u r r e n t a n d n o n - c u r r e n t p r e f e r e n c e e x h i b i t e d b y L a b o r a t o r y f i s h B ( b a r e t r o u g h s ) . R e s u l t s s u m m a r i z e d f r o m s e q u e n t i a l t e s t d e s i g n a n a l y s e s ( C o l e , 1962 )* . A p p r o x i m a t e ^ p e r c e n t o c c u r r e n c e g i v e n i n p a r e n t h e s e s 59 X I V . S u m m a r y of c o a r s e a n d f i n e s u b s t r a t e p r e f e r e n c e e x h i b i t e d b y L a b o r a t o r y f i s h B ( b a r e t r o u g h s ) . A p p r o x i m a t e p e r c e n t o c c u r r e n c e g i v e n i n p a r e n t h e s e s 60 x i i A P P E N D I X Page I. Summary of monthly total d i s s o l v e d solids (TDS) r e c o r d e d at 6 selected stations, L i t t l e C a m p b e ll R i v e r , White Rock, B.C. Stations 1 and 2 under s a l i n i t y effects 75 II. Summary of pH r e c o r d e d at 14 c o l l e c t i n g stations, L i t t l e C a m p b e l l R i v e r , White Rock, B.C '. 76 III. Summary of monthly temperature r e c o r d e d at 14 c o l l e c t i n g stations, M a y 18, 1965 to June 16, 1966, L i t t l e C a m p b e l l R i v e r , White Rock, B.C. 77 IV. Summary of some p h y s i c a l conditions i n Sections A, B and C, L i t t l e C a m p b e ll R i v e r , ' White Rock, B.C. Substrate g r e a t e r than 1.25 cm c o n s i d e r e d c o a r s e , a l l others c o n s i d e r e d fine. Habitats c l a s s i f i e d as c u r r e n t areas if v e l o c i t y g r e a t e r than 23 cm/sec or as non-current areas if l e s s 78 V. Number and d i s t r i b u t i o n of mean depths and v e l o c i t i e s of 132 c o l l e c t i o n sites i n Section A, B and C, August 16, 1965. Mean values a s sembled in groups of 7.6 cm/sec and 7.6 cm f o r c u r r e n t and depth r e s p e c t i v e l y . L i m i t s of r i f f l e , run, flat and pool indicated by dividing l i n e s 79 VI. Summary of mult i p l e r e g r e s s i o n c o e f f i c i e n t s (R) f o r the same analyses p e r f o r m e d on p a r t i t i o n e d data (different method of capture) of Section Sampling ( l o c a l i z e d d i s t r i b u t i o n s ) . D e s c r i p t i o n of analyses given on page 35 80 VII. Summary of c u r r e n t and non-current p r e f e r e n c e s of C. aleuticus and C. asper ( L a b o r a t o r y f i s h A). Sequential test design analyses (Cole, 1962)* employed f o r single tested f i s h ; group f i s h showing over 70 p e r cent o c c u r r e n c e f o r an exp e r i m e n t a l condition c o n s i d e r e d selective 81 VIII. Summary of responses to c u r r e n t and non-current by exp e r i m e n t a l f i s h h e ld over simulated habitat conditions for 60 days ( L a b o r a t o r y f i s h C) 82 1 I N T R O D U C T I O N T h e c o a s t r a n g e s c u l p i n , C o t t u s a l e u t i c u s ( G i l b e r t ) a n d p r i c k l y s c u l p i n , C o t t u s a s p e r ( R i c h a r d s o n ) c o e x i s t i n m a n y s t r e a m s of w e s t e r n C a n a d a . T h e r e i s s o m e e v i d e n c e t h a t b o t h s p e c i e s , w h e n l i v i n g c l o s e t o t h e s e a , m a y u n d e r g o a d o w n s t r e a m m i g r a t i o n p r i o r t o s p a w n i n g ( S h a p o v a l o v a n d T a f t , 1954) . M c A l l i s t e r a n d L i n d s e y (1959) i n d i c a t e t h a t C ^ _ a s p e r p o p u l a -t i o n s w i t h i n 50 m i l e s ( 8 0 . 4 k m ) o f the s e a at H a t z i c L a k e , B . C . d o n o t m i g r a t e t o s p a w n i n c o a s t a l w a t e r s , b u t r a t h e r s p a w n i n f r e s h w a t e r . In t h e L i t t l e C a m p b e l l R i v e r , "White R o c k , B . C . , C . a s p e r w e r e f o u n d t o s p a w n m a i n l y i n e s t u a r i n e w a t e r s . S o m e C . a s p e r a l s o s p a w n e d i n f r e s h -w a t e r c l o s e t o s p a w n i n g C . a l e u t i c u s . F r y of b o t h s p e c i e s c o e x i s t o n l y i n t h e l o w e r p o r t i o n o f the s t r e a m , a s m a l l p a r t of w h i c h i s s u b j e c t e d t o s a l i n i t y c h a n g e s , a n d m o s t o f w h i c h i s u n d e r t i d a l d e p t h e f f e c t s . A s f r y t h e s p e c i e s m a y b e s y m p a t r i c , b u t a s a d u l t s t h e s p e c i e s , w h e r e t h e y o c c u r t o g e t h e r i n t h e L i t t l e C a m p b e l l R i v e r , a p p e a r t o b e l a r g e l y s e g r e g a t e d , o c c u p y i n g d i f f e r e n t m i c r o h a b i t a t s . T h e p r e s e n t s t u d y h a d t w o o b j e c t i v e s : (1) t o d e s c r i b e i n s o m e d e t a i l the s p a t i a l a n d t e m p o r a l d i s t r i b u t i o n s of C . a l e u t i c u s a n d C . a s p e r f r o m t h e f i e l d s t u d y , a n d , (2) t o c o m p a r e e x p e r i m e n t a l l y t h e r e s p o n s e s of t h e t w o s c u l p i n s t o c o n d i t i o n s o f f l o w a n d s u b s t r a t e , i n o r d e r t o a s s e s s , t h e i m p o r t a n c e of t h e s e h a b i t a t c o n d i t i o n s i n s e g r e g a t i o n of t h e s p e c i e s u n d e r n a t u r a l c o n d i t i o n s . 2 D E S C R I P T I O N O F T H E S T U D Y A R E A G E O G R A P H Y A N D G E Q L O G Y T h e L i t t l e C a m p b e l l R i v e r i s a s m a l l s t r e a m a b o u t 4 t o 15 m w i d e a n d 22 k m l o n g , w h i c h f l o w s i n t o S e m i a h m o o B a y at W h i t e R o c k 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 , ( f i g . 1). T h e a v e r a g e g r a d i e n t i s 2 .8 m / k m . T h e r i v e r d r a i n s a n a r e a of 6 3 . 7 s q u a r e k m i n t h e F r a s e r L o w l a n d s of t h e C o a s t a l T r o u g h . T h e F r a s e r L o w l a n d s c o n s i s t of l o w h i l l s , f r o m 15 t o 330 m i n e l e v a t i o n , s e p a r a t e d b y w i d e , f l a t - b o t t o m e d v a l l e y s . T h e v a l l e y of t h e L i t t l e C a m p b e l l R i v e r i s a f o r m e r e m b a y m e n t of t h e s e a ( A r m s t r o n g , 1957) . M a r i n e a n d r a i s e d l i t t o r a l b e a c h d e p o s i t s u n d e r l i e t h e l o w e r r i v e r / a n d t h e l o w e r p a r t of t h e m i d d l e r i v e r ( f i g . 2 B ) w h i l e m o s t of t h e m i d d l e a n d t h e e n t i r e u p p e r r i v e r c o u r s e t h r o u g h g l a c i o - f l u v i a l d e p o s i t s . K e l l y a n d S p i l b u r y (1939) i n d i c a t e the r i v e r f l o w s t h r o u g h f i v e s i m i l a r s o i l t y p e s c o m p o s e d of s a n d , g r a v e l a n d c l a y l o a m s . P r e c i p i t a t i o n a t W h i t e R o c k a v e r a g e s l e s s t h a n o n e m e t e r a n n u a l l y . D E S C R I P T I O N O F T H E S T R E A M S t a t i o n s at w h i c h m o s t of t h e f i e l d w o r k w a s c a r r i e d o u t a r e s h o w n o n a m a p of t h e s t r e a m ( f i g . 2 A ) , a n d o n a v e r t i c a l p r o f i l e ( f i g . 2 B ) . P h y s i c a l m e a s u r e m e n t s a r e s u m m a r i z e d i n T a b l e s I a n d II. F r o m M a y t o O c t o b e r t h e s t r e a m i s f e d m a i n l y b y a s e r i e s of s p r i n g s l o c a t e d 45 m a b o v e m e a n s e a l e v e l ( m . s . l . ) , b e t w e e n S t a t i o n s 10 a n d 12. A b o v e 3 F i g . 1. L o c a t i o n o f L i t t l e C a m p b e l l R i v e r , W h i t e R o c k , B . C . a n d r e s e a r c h f a c i l i t i e s at C o u r t e n a y , V a n c o u v e r I s l a n d , B . C . 4 A 0 2 4 6 8 10 12 14 16 18 20 22 DISTANCE FROM SEA (KM) B F i g . 2. L o c a t i o n of permanent (•) and t e m p o r a r y c o l l e c t i o n stations (o), s t r e a m p r o f i l e and l i m i t s of t i d a l effects. T A B L E I W i d t h , d e p t h a n d p o o l - r i f f l e d e v e l o p m e n t i n d i f f e r e n t a r e a s of L i t t l e C a m p b e l l R i v e r , W h i t e , R o c k , B . C . W i d t h s a n d d e p t h s c a l c u l a t e d f r o m o n e y e a r ' s o b s e r v a t i o n s ; p o o l - r i f f l e r a t i o s d e t e r m i n e d f r o m M a y to N o v e m b e r , 1965. R i v e r s e c t i o n s M a x i m u m r i v e r M i n i m u m r i v e r R a n g e of p o o l M e a n d e p t h of E s t i m a t e d p o o l f r o m m o u t h ( k m ) w i d t h ( m e t e r s ) w i d t h ( m ) d e p t h s ( m ) r i f f l e s ( m ) . r i f f l e r a t i o 0.00-0.54 24 9 0.2 1:0.1 0.54-2.02 24 9 0.9-2.7 0 1:0 2.02-2.17 9 5 0.5-1.8 0.2 1:0.2 L O W E R 2.17-4.47 9 5 0.5-1.8 0.X) 1:0 4.47-6.84 8 3 0.5-1.2 0.1 1:0.2 6.84-12.47 6 2 0.5-1.2 0.2 1:3 M I D D L E 12.47-13.44 6 0 0.5-1.8 0.2 1:0.5 U P P E R 13.44-22.75 60 2 0.5-3.0 o 1:0 R I V E R T A B L E II E s t i m a t e d p e r c e n t a g e s o f s u b s t r a t e t y p e s i n d i f f e r e n t a r e a s of L i t t l e C a m p b e l l R i v e r , W h i t e R o c k , B . C . R e l a t i v e d e g r e e of d e b r i s o v e r l y i n g s u b s t r a t e i n d i -c a t e d b y p l u s m a r k s (+) R i v e r s e c t i o n s O y s t e r C o a r s e F i n e f r o m m o u t h ( k m ) R o c k R u b b l e S h e l l . G r a v e l - G r a v e l f * Saad\'l S i l t - m u d . C l a y . D e b r i s 0 . 0 0 - 0 . 5 4 5 5 25 15 5 10 35 ++++ 0 . 5 4 - 2 .02 2 - 5 8 10 25 40 10 +++ 2 . 0 2 - 2 .17 2 5 - 15 20 50 5 3 - L O W E R 2 . 1 7 - 4 . 4 7 - - - - 5 70 20 5 -4 . 4 7 - 6 . 8 4 - - - 15 25 40 18 2 ++ S e c t i o n A 2 72 12 13 1 + S e c t i o n B - - - 85 7 6 1 1 + S e c t i o n C - - - 70 12 12 1 5 + M I D D L E 6 . 8 4 - 1 2 . 4 7 1 10 - 73 10 10 1 2 + 1 2 . 4 7 - 1 3 . 4 4 5 10 45 15 15 10 + U P P E R 1 3 . 4 4 - 2 2 . 7 5 3 2 - 3 5 2 85 - +++. R I V E R 7 Station 13 the stre a m i s reduced i n summer to a s e r i e s of pools with l i t t l e connecting surface flow. F r o m November to A p r i l , surface drainage r e s u l t i n g f r o m a sharp i n c r e a s e i n p r e c i p i t a t i o n produces a continuous flow f r o m a point about 65 m above m.s.l. T r i b u t a r i e s to the L i t t l e C a m p b e l l R i v e r are few and c o n s i s t m a i n l y of intermittent flows after prolonged r a i n f a l l . The r i v e r can be divided into 3 m a i n areas on the b a s i s of gradient, with the lo w e r a r e a s f u r t h e r subdivided by sal i n i t y effects (fig. 2B). F o r the purpose of f u r t h e r d i s c u s s i o n Station 1 - 3 w i l l c o m p r i s e the lower estuarine r i v e r ; Stations 1 - 8 the lower r i v e r ; Station 9 - 1 2 the middle r i v e r ; and, Sitations 13 - 17 the upper r i v e r . The lower estuarine r i v e r (fig. 3) i s c h a r a c t e r i z e d by fluctuating depths and s a l i n i t i e s due to tides, low gradients (1.1 m/km), low v e l o c i t i e s (0-30 cm/sec), dense summer, aquatic vegetation (Ulva, Enteromorpha), high summer temperatures (26.5°C), high total d i s s o l v e d solids (1100 ppm), and a wide v a r i e t y of f i n e - g r a i n e d substrates including sand, s i l t and c l a y (Table II). Some l a r g e rubble i s found i n the estuarine a r e a as well as extensive beds of oyster s h e l l . The lower r i v e r , f r o m Stations 4 - 8 (fig. 4), i s c h a r a c t e r i z e d by sand and vegetated pools ( E l o d e a sp.) i n the summer, t i d a l depth influences ranging f r o m 3 - 6 0 cm, v e l o c i t i e s f r o m 0 - 4 5 cm/sec, and temperatures to 2jO°C. The middle r i v e r i s c h a r c t e r i z e d by c o a r s e g r a v e l , r i f f l e s (fig. 5) with v e l o c i t i e s to 90 cm/sec, and g r a v e l - s a n d f i l l e d pools (fig. 6) with v e l o c i t i e s l e s s than 7.5 cm/sec. T e m p e r a t u r e s r a r e l y exceed 15°C and the average F i g . 3. Lower, estuarine region of L i t t l e C ampbell R i v e r . A r e a s of c u r r e n t in foreground and non-current in background at low tide (A) and non-current at high tide (B), July, 1965. F i g . .4. T y p i c a l low gradient pool and c u r r e n t a r e a of lower r i v e r . T i d a l influence 0.8 m during summer tides, October, 1965. F i g . 5. R i f f l e a r e a s t y p i c a l of m i d d l e r i v e r b e t w e e n S t a t i o n 9 a n d 12, O c t o b e r , 1965 . F i g . 6. R i f f l e - p o o l c o m p l e x t y p i c a l of t h e m i d d l e r i v e r , O c t o b e r , 1965 . F i g . 7. L a r g e p o o l a n d f l a t w a t e r a r e a s of u p p e r r i v e r b e t w e e n S t a t i o n 14 a n d 17 , O c t o b e r , 1965 . POOL i F" I— 10 gradient i s 6.8 m/km. T h e r e is l i t t l e aquatic vegetation except in the f o r m of enc r u s t i n g algae (Cladophora). The upper r i v e r i s e s s e n t i a l l y an impoundment f r o m May to Ocober (fig. 7) with dense aquatic vegetation o (Nuphar, Potomogeton, Carex, Oenanthe), high temperatures (24 C) and mud substrates. P h y s i c a l and C h e m i c a l F e a t u r e s Water temperatures are e x p r e s s e d i n degrees Centigrade through-out this paper. Summer temperatures r a r e l y exceed 15° at Station 10 although areas upstream and downstream were frequently 10° higher (fig. 8A). Winter temperatures were m ore un i f o r m with only slight warming towards the mouth. C o n s i d e r a b l e l o c a l v a r i a t i o n i n temperature exists. Surface and o bottom water temperatures of upper r i v e r pools d i f f e r e d by 6 on August 3, 1965, while on the same date temperatures i n vegetated flats and adjacent open water at Station 3 and 4 d i f f e r e d by 8° during the daytime and 2j° at night. Water l e v e l s indicate the stream i s e x t r e m e l y stable f r o m e a r l y summer to late f a l l and subject to wide fluctuations during winter and e a r l y s p r i n g (fig. 8C). R e c o r d s f r o m the Department of N o r t h e r n A f f a i r s and N a t i o n a l R e s o u r c e s , Water R e s o u r c e s D i v i s i o n , indicate a d a i l y 3 mean di s c h a r g e between 0.08 and 5.24 m /sec during the p e r i o d of 3 October, 1961 to October, 1964. A low mean monthly flow of 0.14 m /sec 3 and a high of 1.85 m /sec were r e c o r d e d f o r September and F e b r u a r y 11 F i g . 8j. S u m m a r y of s t r e a m t e m p e r a t u r e s ( A , B ) a n d w a t e r l e v e l s ( C ) a t S t a t i o n 10, L i t t l e C a m p b e l l R i v e r . E x p e r i m e n t a l t e m p e r a t u r e s i n d i c a t e d i n B . 12 r e s p e c t i v e l y o f t h e a b o v e i n d i c a t e d p e r i o d . S u m m e r d i s c h a r g e s at S t a t i o n 10 a p p e a r t o b e a p p r o x i m a t e l y h a l f t h o s e a t S t a t i o n 7. T h e d a i l y m e a n 3 d i s c h a r g e at S t a t i o n 10 d u r i n g t h e s u m m e r of 1965 w a s 0 .08 m / s e c . W a t e r l e v e l s ( a n d d i s c h a r g e ) i n t h e L i t t l e C a m p b e l l R i v e r a r e s u b j e c t t o r a p i d a n d w i d e w i n t e r f l u c t u a t i o n s w h i c h a p p e a r t o b e c l o s e l y c o r r e l a t e d w i t h r a i n f a l l a n d p r o b a b l y t o h i g h w a t e r t a b l e l e v e l s . T o t a l d i s s o l v e d s o l i d c o n t e n t d i f f e r e d c o n s i d e r a b l y b e t w e e n s t a t i o n s ( A p p e n d i x I). T h e l o w e r e s t u a r i n e a r e a h a d t h e h i g h e s t v a l u e s , r a n g i n g b e t w e e n 140 a n d 1100 p a r t s p e r m i l l i o n ( p p m ) . T h e m i d d l e r i v e r w a s c o n -s i s t e n t l y l o w e s t i n d i s s o l v e d s o l i d s ( 4 0 - 1 1 6 p p m ) w h i l e the u p p e r a n d l o w e r r i v e r w e r e s l i g h t l y h i g h e r ( 5 0 - 1 4 9 p p m ) . A n a l y s e s of h y d r o g e n i o n c o n t e n t a t 14 c o l l e c t i n g s t a t i o n s a l o n g t h e l e n g t h o f t h e s t r e a m i n d i c a t e d a g e n e r a l r a n g e of 7.2 t o 8 .9 d u r i n g t h e p e r i o d of J u l y , 1965 t o J u n e , 1966 ( A p p e n d i x II). T h e h i g h e s t p H v a l u e s w e r e r e c o r d e d i n t h e w i n t e r m o n t h s . H i g h e s t v a l u e s o n a n y g i v e n d a y w e r e r e c o r d e d a t u p p e r r i v e r a n d l o w e r , e s t u a r i n e s t a t i o n s of t h e s t r e a m . B i o l o g i c a l F e a t u f e^ s'-' ' L e s s t h a n 15 s p e c i e s of f i s h o c c u r i n the s t r e a m , t h e n u m b e r of s p e c i e s d e c r e a s i n g f r o m m o u t h t o s o u r c e . F o u r of t h e 12 i d e n t i f i e d s p e c i e s a r e r e s t r i c t e d t o e s t u a r i n e w a t e r s . L e p t o c o t t u s a r m a t u s a n d P l a t i c h t h y s s t e l l a t u s a r e c o m m o n l y f o u n d a b o v e e s t u a r i n e l i m i t s . C a t o s t o m u s c a t o s t o m u s w e r e r a r e a n d o c c u p i e d o n l y a s m a l l a r e a 13 b e t w e e n S t a t i o n s 13 a n d 15. O n c o r h y n c h u s k e t a w e r e r a r e l y c a p t u r e d d u e t o t h e i r i m m e d i a t e d o w n s t r e a m m i g r a t i o n a f t e r h a t c h i n g . C o t t u s a l e u t i c u s w e r e m o s t o f t e n a s s o c i a t e d w i t h S a l m o g a i r d n e r i i w h i l e C . a s p e r w e r e m o s t o f t e n a s s o c i a t e d w i t h O . k i s u t c h . A l t h o u g h n o e x t e n s i v e s t u d y w a s u n d e r t a k e n o n the i n v e r t e b r a t e s of t h e L i t t l e C a m p b e l l R i v e r , d i f f e r e n c e s i n n u m b e r s a n d s p a t i a l d i s t r i b u t i o n o f t h e f a u n a w e r e a p p a r e n t , p a r t i c u l a r l y w h e n c o m p a r i n g t h e l o w e r , m i d d l e a n d u p p e r a r e a s of t h e s t r e a m . T h e e s t u a r i n e a r e a w a s b y f a r t h e m o s t p r o d u c t i v e i n t e r m s of t o t a l n u m b e r s a n d s p e c i e s . C r u s t a c e a n s , m o l l u s c s a n d a n n e l i d s d o m i n a t e d t h e f a u n a . T h e m i d d l e r i v e r w a s p o p u l a t e d m a i n l y b y a q u a t i c i n s e c t s i n c l u d i n g E p h e m e r o p t e r a , D i p t e r a , T r i c h o p t e r a , P l e c o p t e r a , C o l e o p t e r a a n d M e g a l o p t e r a ( G . R . P e t e r s o n , p e r s . c o m m ) . T h e u p p e r r i v e r h a d a r i c h f a u n a o f m o l l u s c s , a m p h i p o d s a n d d i p t e r a n s . A l t h o u g h s o m e s p e c i e s of E p h e m e r o p t e r a w e r e p r e s e n t , P l e c o p t e r a a n d T r i c h o p t e r a w e r e a b s e n t . M E T H O D S A N D A P P A R A T U S ( F I E L D S T U D I E S ) R e c o r d i n g of E n v i r o n m e n t a l F e a t u r e s / W a t e r t e m p e r a t u r e w a s r e c o r d e d b y u s e o f a c o n t i n u o u s t e m p e r a t u r e r e c o r d e r ( T a y l o r ) , a n e l e c t r o n i c t h e r m o m e t e r w i t h a t h e r m i s t o r p r o b e ( M o d e l F T - 2 , A p p l i e d R e s e a r c h A s s o c i a t e s ) a n d a s t a n d a r d p o c k e t t h e r m o -m e t e r . T h e c o n t i n u o u s r e c o r d e r w a s l o c a t e d 10 k m f r o m t h e s e a i n t h e r e g i o n of S t a t i o n 10 a n d S e c t i o n s A , B a n d C ( f i g . 2 B ) . T e m p e r a t u r e s 14 w e r e r e c o r d e d m o n t h l y at 14 c o l l e c t i n g s t a t i o n s d u r i n g t h e s t u d y ( A p p e n d i x III). A l l i n s t r u m e n t s w e r e c a l i b r a t e d a g a i n s t a s t a n d a r d c e n t i g r a d e t h e r m o -m e t e r . S t r e a m l e v e l w a s r e c o r d e d o n g a u g e s l o c a t e d at S t a t i o n s 3, 7 , 9 a n d 10. E s t i m a t i o n o f d i s c h a r g e at S t a t i o n 10 w a s o b t a i n e d b y r e c o r d i n g v e l o c i t y w i t h a G u r l e y F l o w M e t e r ( N u m b e r 625) a c r o s s a s t a b l e s t r e a m s e c t i o n . W a t e r s a m p l e s f o r t o t a l d i s s o l v e d s o l i d c o n t e n t ( A p p e n d i x I) w e r e c o l l e c t e d m o n t h l y at 6 s t a t i o n s a n d l a t e r a n a l y z e d i n t h e l a b o r a t o r y w i t h a i M o d e l R A - 2 A C o n d u c t i v i t y M e t e r ( I n d u s t r i a l I n s t r u m e n t s I n c . ) . S a m p l e s w e r e c o l l e c t e d i n c o n j u n c t i o n w i t h p H a n d t e m p e r a t u r e s e r i e s b e t w e e n 1130 a n d 1300 h o u r s . D e t e r m i n a t i o n s o f p H ( A p p e n d i x II) w e r e m a d e i n t h e s t r e a m w i t h the a i d of a M o d e l 3 0 - C P o r t a b l e p H M e t e r ( E l e c t r o n i c I n s t r u m e n t L t d . ) . O p e r a t i o n o f D o w n s t r e a m T r a p A l t h o u g h m o s t of t h e i n f o r m a t i o n o n s c u l p i n m o v e m e n t w a s o b t a i n e d b y d a y a n d n i g h t s e i n i n g , a n i n c l i n e d s k i m m e r - t y p e t r a p , l o c a t e d i n the m i d d l e p a r t of t h e r i v e r ( b e l o w S t a t i o n 10) , w h i c h s a m p l e * ! the e n t i r e s t r e a m d u r i n g s u m m e r , r e c o r d e d n u m b e r s of f i s h m o v i n g d o w n s t r e a m . T h e t r a p w a s o p e r a t e d b e t w e e n J u l y 14, 1965 a n d O c t o b e r 2 2 , 1 9 6 5 . T h e t r a p w a s s e r v i c e d d a i l y u n t i l A u g u s t a n d t h e r e a f t e r e v e r y s e c o n d d a y . N u m b e r s of f i s h r e c o r d e d i n F i g u r e 9 B w e r e g r o u p e d f o r t w o d a y c a t c h p e r i o d s . T r a p -c a u g h t f i s h w e r e m a r k e d a n d r e l e a s e d i n t o S e c t i o n B b e l o w t h e t r a p . . 9. Length-frequency d i s t r i b u t i o n s (A) and numbers (B) of C. aleuticus and C. asper taken in a downstream trapT Section B. Water l e v e l s and temperatures r e c o r d e d i n trap region. 16 Seining Procedure Most of the information on occurrence of sculp ins in the Little Campbell River was obtained by seining; each seine haul was a collection of 5.57 sq. meters (60 sq. ft.) over a representative, homogenous habitat. A 6 mm mesh nylon seine, 2.5 m wide and 2 m deep, mounted on aluminum poles and heavily weighted was employed. The lead line was equipped with a number of 'roller'-type leads, spaced 10 cm apart, which disturbed the substrate, thereby facilitating capture of the bottom-dwelling sculpins. The direction of the seine hauls was upstream and always from deep to shallower waters. Seining in areas of high velocities was accomplished by placing the seine in a stationary position and disturbing the substrate manually upstream in a 5.57 sq. meter area. Sampling Systems Three systems of sampling were employed to document spatial and temporal distribution of sculpins: (1) monthly collections at 14 stations from August to November, 1965 and in February, 1966 constituted the sampling referred to as Block Seining. A total of 420 collections were made, representing 84 haul sites and 5 dates. This sampling method documented distribution of fish along the length of the stream; (2) Section Sampling refers to data collected at 132 haul sites along a 600 m length of stream near Station 10 (fig. 2B). This sampling documented local distri-bution of fish.. The area was divided into 3 sections with the furthest 17 u p s t r e a m designated as Section A. Sections A and B were each a p p r o x i -m a t e l y 125 m long, separated by a 180 m zone. Section C was immediately downstream of Section B and was 110 m long. Sections A and C were f r e e l y a c c e s s i b l e to moving f i s h while Section B was c l o s e d to downstream m i g r a n t s by a trap at its u p stream end and to u p s t r e a m m i g r a n t s by a drop st r u c t u r e at its lower end. Sections A and B were used for population estimates and long t e r m observation of movement while Section C was sampled m a i n l y to m e a s u r e d i e l movement and e m i g r a t i o n f r o m Section B:; (3) Station Seining r e f e r s to s p e c i f i c sampling sites such as the i n t e r t i d a l zone and other a r e a s of the tide-induced depth fluctuations. D e s c r i p t i o n and M e a s u r e m e n t of V a r i a b l e s The number of f i s h caught in one seine, haul was used as the dependent v a r i a b l e i n r e g r e s s i o n analyses. The 9 dependent v a r i a b l e s included total number of C. a s p e r andoof C. aleuticus; young-of-the-year (fry) ,C. a s p e r and C. aleuticus; y e a r l i n g C. a s p e r and C. aleuticus; adult C. a s p e r and C. aleuticus; and the ra t i o of total number of C. a s p e r to total number of C. aleuticus. On the b a s i s of length frequency data young-of-the-year (fry) were c o n s i d e r e d to be f i s h l e s s than 40 mm standard length; y e a r l i n g f i s h between 41 and 64 mm; and adult f i s h g r e a t e r than 65 mm. The following seven environmental p a r a m e t e r s were used as independent v a r i a b l e s : ve l o c i t y , substrate, month, time of day, distance u pstream f r o m mouth, depth, and aquatic plant cover. The m a i n 18 hypothesis was that v e l o c i t y and substrate were important environmental f a c t o r s affecting the d i s t r i b u t i o n of the two sculpins, C. a s p e r and C. aleuticus. V e l o c i t y and depth were e x p r e s s e d i n t h e i r o r i g i n a l units of measurement, while substrate, vegetative cover, month, time of day and distance f r o m the mouth were as s i g n e d a r b i t r a r y rank values. Substrate types were c l a s s i f i e d a c c o r d i n g to c o a r s e n e s s with mud as 1, c l a y as 2, sand as-3, sand-gravel m i x as 5, fine g r a v e l as 6, medium g r a v e l as 7, c o a r s e g r a v e l as 8, and rock as 10. F i n e g r a v e l ranged b e t w e e n 2.5 and 24 mm, medium g r a v e l between 25 and 49 mm and c o a r s e g r a v e l between 50 and 75 mm. Vegetative c o v e r was g r o s s l y quantified as 1, 2 o r 3, r e p r e s e n t i n g light, medium and heavy concentrations. T i m e of day was coded as daylight (1) and dark n e s s (0) while months were coded w i t h June a s s i g n e d a value of unity, J u l y a value of two, etc. The coded value f o r month, r a i s e d to the second power, was employed i n some analyses because it was fel t that the p e r i o d of observations might span s o m e intermediate favourable p e r i o d f o r f i s h d i s t r i b u t i o n p r e c e d e d and followed b y p e r i o d s of l e s s favourable conditions. L o c a t i o n of each c o l l e c t i o n site i n r e l a t i o n to the mouth of the r i v e r (Dismouth) was given the f o l l o w i n g coded values: zone of s a l i n i t y influence = 1; downstream, a r e a of low gradient and t i d a l influence = 2; downstream a r e a of low gradient and no t i d a l influence = 3; high gradient a r e a = 4; and upstream, low gradient a r e a = 5. 19 D e s c r i p t i o n o f A n a l y s e s S i m p l e a n d m u l t i p l e r e g r e s s i o n a n a l y s e s w e r e p e r f o r m e d t o d e t e r m i n e w h a t i n d e p e n d e n t v a r i a b l e s w e r e m o s t u s e f u l a s p r e d i c t o r s of f i s h a b u n d a n c e . M a n y o f the i n d e p e n d e n t v a r i a b l e s w e r e c o r r e l a t e d w i t h o n e a n o t h e r , a n d a s a r e s u l t , t h e s i g n i f i c a n c e of a n y o n e v a r i a b l e , a s j u d g e d f r o m t h e s i m p l e r e g r e s s i o n r e l a t i o n s h i p , c o u l d e a s i l y b e e x a g g e r a t e d o r m a s k e d . F o r e x a m p l e , h i g h c u r r e n t v e l o c i t y u s u a l l y i s e n c o u n t e r e d o v e r c o a r s e s u b s t r a t e , a n d at s h a l l o w d e p t h s . T h e r e f o r e m u l t i p l e r e g r e s s i o n a n a l y s i s w a s u s e d t o e v a l u a t e t h e i m p o r t a n c e of e a c h i n d e p e n d e n t v a r i a b l e , w h i l e s i m u l t a n e o u s l y t a k i n g i n t o a c c o u n t t h e e f f e c t s o f t h e o t h e r i n d e p e n d e n t v a r i a b l e s . T o c o m p a r e t h e r e l a t i v e i m p o r t a n c e of v a r i o u s f a c t o r s m e a s u r e d i n d i f f e r e n t u n i t s a s p r e d i c t o r s of f i s h a b u n d a n c e , s t a n d a r d p a r t i a l r e g r e s s i o n c o e f f i -c i e n t s ( S t e e l a n d T o r r i e , 284:1/4,6) w e r e c a l c u l a t e d . T h e s q u a r e of the 2 m u l t i p l e r e g r e s s i o n c o e f f i c i e n t , R , r e p r e s e n t s t h e f r a c t i o n of t h e t o t a l v a r i a b i l i t y i n f i s h a b u n d a n c e w h i c h i s r e l a t e d t o a l l the f a c t o r s i n c l u d e d i n a p a r t i c u l a r r e g r e s s i o n a n a l y s i s . I n t e r p r e t a t i v e p r o b l e m s a r i s e w h e n a n a r r a y o f e n v i r o n m e n t a l f a c t o r s i s t e s t e d f o r s o m e r e l a t i o n s h i p t o o n e o r m o r e of s e v e r a l d e p e n d e n t v a r i a b l e s ( the m e a s u r e of f i s h a b u n d a n c e ) a s i s d o n e h e r e . T o p a r t i a l l y c i r c u m v e n t t h i s d i f f i c u l t y , a t t e n t i o n w a s f o c u s e d o n t h o s e e n v i r o n m e n t a l f a c t o r s w h i c h w e r e j u d g e d s i g n i f i c a n t a t c o n v e n t i o n a l s t a t i s t i c a l l e v e l s , a n d w h i c h t e n d e d t o b e j u d g e d s i g n i f i c a n t c o n s i s t e n t l y i n the v a r i o u s a n a l y s e s . 20 Population E s t i m a t e s Single censuses (Peterson-type) using seines and e l e c t r i c shocking were employed f o r estimating s c u l p i n populations i n Sections A and B using the m o d i f i e d formulae of B a i l e y ( R i c k e r , 84:3,7). A number of m a r k e d and unmarked f i s h of representative s i z e s of both species were he l d i n wire baskets during the p e r i o d of estimates. No significant d i f f e r e n c e i n m o r t a l i t y o c c u r r e d between m a r k e d and unmarked f i s h and f i n - c l i p s r e m a i n ed c l e a r l y recognizable. Observations of m a r k e d f i s h i n the l a b o r a t o r y suggested that f i s h movement was not i m p a i r e d by m a r k i n g and there was no reaso n to expect unequal v u l n e r a b i l i t y to capture. A drop str u c t u r e at the bottom end and a trap at the upstream end of Section B prevented recruitment during the estimates. L o s s by movement out of Section B was neg l i g i b l e as indicated by r e c o v e r y of only 4 m a r k e d f i s h i n the a r e a i m m e d i a t e l y downstream. L o s s of m a r k e d f i s h f r o m Section A was a l s o found, by sampling above and below the section, to be negligible. T h e r e was close agreement of m a r k e d to unmarked ratios i n the habitats indicating the m a r k i n g had been random with r e s p e c t to habitat location. T h e r e was reasonably good c o r r e l a t i o n between numbers and size range of f i s h i n m a r k e d and r e c a p t u r e d groups (fig. 10). Stomach and Intestinal T r a c t A n a l y s e s F i s h c o l l e c t e d f r o m Section B in the high gradient p o r t i o n of the stream, were u t i l i z e d f o r a n a l y s i s of stomach and int e s t i n a l t r a c t weight MARKED (M) RECAPTURED (C) MARKED RECAPTURES (R) STANDARD LENGTH (MM) F i g . 10. L e n g t h - f r e q u e n c y d i s t r i b u t i o n o f C . a l e u t i c u s i n p o p u l a t i o n e s t i m a t e s , J u l y 15 - 18, 1965 , S e c t i o n s A a n d B , L i t t l e C a m p b e l l R i v e r . 22 a n d v o l u m e s . P e r c e n t o c c u r r e n c e of f o o d i n i n t e s t i n a l t r a c t w a s a l s o m e a s u r e d b y p l a c i n g t h e t r a c t o n a m i l l i m e t e r s c a l e a n d d e t e r m i n i n g t h e l e n g t h of t r a c t o c c u p i e d . C o n t e n t s of t h e s t o m a c h a n d l o w e r t r a c t w e r e b l o t t e d o n a b s o r p t i v e p a p e r f o r 1 m i n u t e a n d w e t - w e i g h e d t o a n a c c u r a c y of h u n d r e d t h s of a g r a m o n a M e t t l e r K 7 / T p a n b a l a n c e . N o q u a n t i t a t i v e m e a s u r e of f o o d g r o u p s w a s a t t e m p t e d . E q u a l - s i z e d s a m p l e s of a n u m b e r o f s i z e g r o u p s of f i s h w e r e t a k e n at 1100 a n d 2 3 0 0 h o u r s i n b o t h r i f f l e a n d p o o l e n v i r o n m e n t s ( T a b l e I X ) . M E T H O D S A N D A P P A R A T U S ( L A B O R A T O R Y S T U D I E S ) H o l d i n g C o n d i t i o n s E x p e r i m e n t s w e r e c o n d u c t e d a t r e s e a r c h f a c i l i t i e s of t h e B r i t i s h C o l u m b i a F i s h a n d W i l d l i f e B r a n c h at C o u r t e n a y , B . C . b e t w e e n J u l y 15 a n d O c t o b e r 4, 1 9 6 5 . F i s h w e r e o b t a i n e d f r o m t h e s t u d y s t r e a m a t W h i t e R o c k , B . C . a n d t r a n s f e r r e d t o C o u r t e n a y o n V a n c o u v e r I s l a n d . S o m e a d d i t i o n a l f i s h w e r e c o l l e c t e d f r o m B i g Q u a l i c u m R i v e r , N i l e C r e e k , P u n t l e d g e a n d T s o l u m R i v e r s , V a n c o u v e r I s l a n d , B . C . T h e s c u l p i n s w e r e h e l d s e p a r a t e l y i n a s e r i e s of h a t c h e r y t r o u g h s at t e m p e r a t u r e s r a n g i n g b e t w e e n 1 2 . 5 ° a n d 1 8 . 0 ° ( f i g . 8 B ) . O n e t r o u g h w a s u s e d t o h o l d f i e l d f i s h o v e r n i g h t p r i o r t o t e s t i n g , 3 b a r e t r o u g h s h e l d f i s h s e p a r a t e d b y s p e c i e s a n d s i z e g r o u p f o r a 6 0 - d a y p e r i o d , w h i l e a s e r i e s of t r o u g h s h e l d f i s h u n d e r c o m b i n a t i o n s o f w a t e r f l o w a n d s e l e c t e d s u b s t r a t e f o r 60 d a y s . T h e a r t i f i c i a l h o l d i n g c o n d i t i o n s i n c l u d e d c o m p a r t m e n t s of F i g . 11. C o n t i n u o u s f l u m e with, m o d i f i e d t e s t i n g s e c t i o n i n d i c a t e d b e t w e e n p o i n t s X a n d Y . 1 . F i g . 12. A r t i f i c i a l h o l d i n g - h a b i t a t s a t r e s e a r c h f a c i l i t i e s , C o u r t e n a y , B . C . B a r e t r o u g h ( A ) , s u b s t r a t e a n d .. .. n o n - c u r r e n t ( B ) a n d . s_ubstrate a n d c u r r e n t ( C ) . F i g . 13. E x p e r i m e n t a l t e s t i n g s e c t i o n of c o n t i n u o u s f l u m e w i t h s u b s t r a t e c e l l ' s i l l u s t r a t e d . C u r r e n t f l o w ' f r o m p o i n t X t o Y . 24 c o a r s e and fine substrate with, and without, water flow (fig. 12). The g r a v e l of the c o a r s e substrate m e a s u r e d 40 to 50 mm and m o r t a r sand c o m p r i s e d the fine substrate. Water ve l o c i t y i n troughs with c u r r e n t was a p p r o x i m a t e l y 30 cm/sec while non-current troughs had v e l o c i t i e s l e s s than 7 cm/sec. The water l e v e l was maintained at a depth of 22 cm. The above a r t i f i c i a l holding conditions simulated habitats found in the f i e l d . Cottus aleuticus and C. a s p e r were thus held in habitats n o r m a l l y occupied and those i n which they r a r e l y or never o c c u r r e d . T r oughs were i l l u m i n a t e d with f l u o r e s c e n t bulbs and f i s h were exposed to a d a i l y 14-hour photoperiod between 0800 and 2200 hours. F i s h were fed d a i l y at 2130 hours a combination of ground salmon, pork, beef l i v e r and trout food p e l l e t s . E x p e r i m e n t a l Stream and T e s t Section E x p e r i m e n t s were conducted i n a m o d i f i e d section (fig. 13) of a continuous flume s i m i l a r to one d e s c r i b e d by T. G. Northcote in 1962 (fig. 11). The m o d i f i e d section was 153 cm long, 50 cm wide and 31 cm deep (fig. 14). T o create c u r r e n t and non-current channels a d i v i d e r 125 cm i long and 28 cm deep was i n s t a l l e d . The channels c r e a t e d by the d i v i d e r m e a s u r e d 25 cm wide. Water was d i v e r t e d into the channels at different v e l o c i t i e s by means of plates and s c r e e n s of v a r i o u s - s i z e d mesh. F i s h were introduced at P o i n t 9 (fig. 14) of the test section through a length of p l a s t i c pipe. Removable s c r e e n s i m m e d i a t e l y upstream of the introduction 25 point were used to isolate f i s h f r o m the testing apparatus p r i o r to group testing. The channel f l o o r s sloped up toward the downstream end of the test section and t e r m i n a t e d in a short downward ramp. The upward slope c r e a t e d a m o r e u n i f o r m v e l o c i t y along the length of the channels as d e s c r i b e d by Gee (1961). Viewing plates allowed observation of the two channels when the d i v i d e r was in position. The viewing plates were c o v e r e d with black p l a s t i c sheeting and slots cut the length of the test section afforded observation. The top of the test section was c o v e r e d with a t r a n s l u c e n t p l a s t i c sheeting and lighting was p r o v i d e d by a single 100-w bulb. E n v i r o n m e n t a l T e s t Conditions V e l o c i t i e s were m e a s u r e d 1.5 cm above the surface of the test section with a G u r l e y flow meter. C u r r e n t patterns within the test section were obse r v e d with f l u o r e s c e i n dye. Water temperatures of the holding troughs, test section and c o l l e c t i o n s t r e a m were s i m i l a r . Water temperature rose some 2° du r i n g 8 hours of stre a m tank operation. L a b o r a t o r y holding temperatures were noticeably higher than s t r e a m temperatures only during the l a s t two weeks of August (fig. 8B). The water l e v e l i n the test section was maintained at a depth of 22 cm. C o a r s e substrate m e a s u r e d 40 to 50 mm (gravel) and m o r t a r sand c o m p r i s e d the fine substrate. The co a r s e substrate was dark i n c o l o r while the fine substrate was light. C u r r e n t speeds of 45 cm/sec were used i n the flow channel. 26 3 5 5J ft! i II 2 12 6 ;5 12 II 1— 10 : 8 1 4 3 TOP VIEW • • • 1 1 « 5 : ! 3 ^ / 8 7 9 L — : ~1 5 SIDE VIEW LEGEND 7. CHANNEL DIVIDER 8. CREST OF INCLINE RAMP 9. INTRODUCTION POINT 10. OUTFLOW 11. SUBSTRATE CELL (FINE) 12. SUBSTRATE CELL (COARSE) 1. CHANNEL I 2. CHANNEL 2 3. VIEWING PLATE 4. INFLOW 5. REMOVABLE SCREENS 6 . REMOVABLE PLATE F i g . 14. E x p e r i m e n t a l s e c t i o n of a c o n t i n u o u s f l u m e w i t h s u b s t r a t e c e l l s a n d f l o w c h a n n e l s i n d i c a t e d . 27 T e s t s were c a r r i e d out on (1) f i s h brought d i r e c t l y f r o m the f i e l d ; (2) f i s h h e ld in bare troughs for 60 days;;and, (3) f i s h held over a r t i f i c i a l habitats f o r 60 days. The flow p r e f e r e n c e , substrate p r e f e r e n c e and simultaneous choice of flow and substrate, was m e a s u r e d f o r the following m a i n size groups: 20-25, 35-40, 60-65, 85-90, and 110 mm plus. The number of f i s h used i n each test is s u m m a r i z e d in T a b l e s X to XIV. No f i s h were used m o re than once during a p a r t i c u l a r experiment. F i s h were tested both singly and in groups of fifteen with no m i x i n g of species in any experiments. Response to flow and substrate was m e a s u r e d by r e c o r d i n g the flow channel and/or substrate c e l l each f i s h occupied. F low and substrate se l e c t i o n by single f i s h was r e c o r d e d at 3 seconds, 30 seconds and 15 minutes while the p o s i t i o n of group-tested f i s h was, in addition, r e c o r d e d e v e r y 5 minutes f o r a p e r i o d of up to 7 hours. At the end of a test f i s h were f i n c l i p p e d (not to be re-used) and returned to t h e i r o r i g i n a l holding trough. F i s h were fixed i n 1 0 % f o r m a l i n and p r e s e r v e d in 4 0 % i s o p r o p y l a l c ohol at the end of l a b o r a t o r y studies f o r l a t e r d e t e rmination of sex, length, gonad weight and total weight. R E S U L T S ( F I E L D STUDIES) A n a l y s e s of Seining Data M a i n i n t e r e s t was centred on the hypothesis that substrate and water ve l o c i t y were important determinants of sculpin abundance, p o s s i b l y 28 affecting l o c a l and l a r g e - s c a l e segregation of the two species in the L i t t l e C a m p b e l l R i v e r . M u l t i p l e r e g r e s s i o n analyses were c a r r i e d out so that additional environmental v a r i a b l e s could be examined f o r p o s s i b l e r e l a t i o n -ships with s c u l p i n abundance, and to m i n i m i z e the influence these-additional v a r i a b l e s might have through in t e r c or r e l a t i o n , on integrations involving the independent v a r i a b l e s of p r i n c i p l e interest, c u r r e n t v e l o c i t y and substrate. The v a r i o u s independent and dependent v a r i a b l e s and different sets of data pr o v i d e a total of 435 p o s s i b l e p a i r i n g s of v a r i a b l e s , of which 152 y i e l d e d s t a t i s t i c a l l y s ignificant c o r r e l a t i o n s (P<0.05). The frequent o c c u r r e n c e of f a i r l y high c o r r e l a t i o n s among independent v a r i a b l e s can be seen in T a b l e s III and IV. (1) B r o a d - S c a l e D i s t r i b u t i o n s B l o c k Seining data, c o l l e c t e d over stations throughout the stream, provide insight into factors, affecting the b r o a d - s c a l e d i s t r i b u t i o n and abundance of the two species of sculpins in the L i t t l e C a m p b e l l R i v e r . T h r e e separate analyses were c a r r i e d out, as follows: M u l t i p l e R e g r e s s i o n A n a l y s i s (I) The environmental f a c t o r s c o n s i d e r e d for this a n a l y s i s were velocity, substrate, depth, cover, month, month«squared and distance f r o m mouth of the stream. The dependent v a r i a b l e s include the size groupings and species r a t i o as outlined in Methods and Table V. The abundance of C. asper, f o r i n d i v i d u a l s i z e groups and as a total of a l l groups, was best estimated by the c o v e r p a r a m e t e r (vegetation) and distance f r o m the mouth T A B L E III C o r r e l a t i o n c o e f f i c i e n t s f o r p a i r s of environmental v a r i a b l e s , B l o c k A n a l y s i s (broad-scale f i s h d i s t r i -bution), 1965-66. Dismouth Substrate T i m e C o v e r Depth V e l o c i t y Month 0.127 0.021 0.123 0.039 0.338 0.211 0.196 0.037 0.034 0.097 0.113 Distance f r o m s t r e a m mouth Substrate 0.054 0.334 0.264 0.234 T i m e of day 0.039 0.025 0.096 P l a n t c o v e r 0.027 0.318 Depth 0.257 30 T A B L E IV C o r r e l a t i o n c o e f f i c i e n t s f o r p a i r s of environmental v a r i a b l e s , S e c t i o n A n a l y s i s , (lo c a l f i s h d i s t r i b u t i o n ) , 1965-66. Dismouth Substrate T i m e C o v e r Depth V e l o c i t y Month 0.612 0.022 0.612 0.000 0.014 0.003 Distance f r o m s t r e a m mouth 0.036 1.000 0.000 0.022 0.005 Substrate 0.036 0.000 0.703 0.585 T i m e of day P l a n t c o v e r Depth 0.000 0.224 0.005 0.000 0.000 0.740 T A B L E V Summary of significant independent v a r i a b l e s i n a s e r i e s of m u l t i p l e r e g r e s s i o n s . Data f r o m b r o a d - s c a l e d i s t r i b u t i o n s ( B l o c k Seining), 1965-66, L i t t l e C a m p b e ll R i v e r , White Rock, B.C. Standard p a r t i a l r e g r e s s i o n coefficients are indicated and l e v e l s of sig n i f i c a n c e , P<0.05 (*) and P<0.01 (**). Descriptionrof v a r i a b l e s used i n the analyses are found on pages 28 and 32. M u l t i p l e R e g r e s s i o n Independent A n a l y s e s V a r i a b l e s (X) F r y Y e a r l i n g s Adults T o t a l Dependent V a r i a b l e s (Y) C. A L E U T I C U S C. A S P E R (I) (II) (HI) Substrate V e l o c i t y 0.176** 0.223** C o v e r (plant) Depth Distance (mouth) 0.165** Month Month-squared Substrate V e l o c i t y 0.171** 0.160** C o v e r (plant) Depth Distance (mouth) -0.126* T o t a l C a s p e r 0.231** Substrate V e l o c i t y 0.184** 0.155** C o v e r (plant) Depth -T o t a l C a s p e r 0.258** 0.199** 0.151** F r y Y e a r l i n g s Adults T o t a l 0.145** 0.124** 0.135** 0.197** 0.224** 0.187** 0.179** •0.115* 0.277** 0.190*: 0.252** -0.231** 0.629* -0.593 -0.194** 0.609* -0.599* Ratio 0.162*= -0.165** 32 of the stream. Cottus aleuticus was best estimated by the v e l o c i t y p a r a m e t e r . M u l t i p l e R e g r e s s i o n A n a l y s i s (II) The environmental p a r a m e t e r s , month and month-squared were dropped f r o m this a n a l y s i s as they were never s i g n i f i c a n t l y r e l a t e d to the abundance of C. aleuticus i n A n a l y s i s (I). The total number of C. asper was now c o n s i d e r e d as an independent v a r i a b l e i n o r d e r to determine whether the abundance of C. a s p e r had a d i s c e r n i b l e effect upon the abundance of C. aleuticus. A l l other independent v a r i a b l e s used i n A n a l y s i s (I) were retained. T a b l e V indicates that total number of C. a s p e r can be used as an e s t i m a t o r of total number of C. aleuticus or of C. aleuticus f r y . A c t u a l l y , f r y make up most of the total of C. aleuticus i n these samples. V e l o c i t y was a better e s t i m a t o r of C. aleuticus abundance in the sense that it is s i g n i f i c a n t l y r e l a t e d to the y e a r l i n g group as well as the two p r e v i o u s l y mentioned groups. M u l t i p l e R e g r e s s i o n A n a l y s i s (III) A l l p a r a m e t e r s were s i m i l a r to those used i n A n a l y s i s (II) except distance f r o m the mouth of the s t r e a m was eliminated. It was o r i g i n a l l y accepted at the 5 p e r cent l e v e l , but not at the 1 p e r cent l e v e l . T a b l e V indicates that total number of C. asper was s t i l l the best e s t i m a t o r of C. aleuticus abundance; however, as in A n a l y s i s (II), f r y 33 make up most of the total f o r C. aleuticus. V e l o c i t y continued to be the most consistent e s t i m a t o r of C. aleuticus abundance as it was significant in two out of the three size groups making Up total number of C. aleuticus. The sign of a r e g r e s s i o n c o e f f i c i e n t was useful i n i n t e r p r e t i n g the re l a t i o n s h i p between the environmental v a r i a b l e concerned, and f i s h abundance. F r o m Tabl e V ( A n a l y s i s I) it can be seen that C. asper are more abundant in ^  c o a r s e than i n fine substrate; m o r e abundant in heavy than i n sparse plant cover; m o re abundant in deep than i n shallower water (adults); l e s s abundant as one moves upstream f r o m the stre a m mouth (total number and y e a r l i n g s ) ; and, they v a r y i n abundance in a c u r v i l i n e a r fashion o v e r the s e v e r a l months of sampling, being l e s s abundant at the intermediate dates (total number and y e a r l i n g s ) . Cottus aleuticus are more abundant in fast water than in slow (total number, f r y and y e a r l i n g s ) ; and l e s s abundant as the distance f r o m the mouth of the s t r e a m i n c r e a s e s (total number and f r y ) . The r a t i o of the number of C. asper to the number of C. aleuticus d e c r e a s e s as the distance f r o m the mouth of the stream i n c r e a s e s . In A n a l y s e s (II) and (III), the same pattern as above p e r s i s t s f o r the m e a s u r e s of abundance of C. aleuticus. It was found that i n addition to the effects of water v e l o c i t y and distance f r o m the stre a m mouth, C. aleuticus f r y (and because of the overwhelming contribution of f r y to total counts this i s true of the total number of C. aleuticus also) are m o r e abundant in ar e a s where C. as p e r are abundant than i n areas where C. asper are s c a r c e . It 34 must be r e m e m b e r e d that these data r e f l e c t streamwide, not l o c a l , d i s t r i b u -tional patterns. C o m p a r i s o n of B l o c k Seining data f o r the p e r i o d of F e b r u a r y , I960 to F e b r u a r y , 1962 (R.J. K r e j s a , unpubL) and August, 1965 to F e b r u a r y , 1966 r e v e a l e d that C. a s p e r were best estimated by the environmental p a r a m e t e r s plant c o v e r and distance f r o m the mouth of the stream while C. aleuticus was estimated most co n s i s t e n t l y by v e l o c i t y and total number of C. asper. C o l l e c t i o n sites were s i m i l a r i n both sampling p e r i o d s ; the number of c o l l e c t i o n s at each station was doubled in 1965-1966. In both c o l l e c t i o n p e r i o d s the sampling sites were c o n s i d e r e d to be representative of the habitats avail a b l e . C o m p a r i s o n of habitat quantity and quality r e v e a l e d l i t t l e o bservable change in the I960 to 1966 p e r i o d . I n , a l l analyses of B l o c k Seining data, the multiple c o r r e l a t i o n c o e f f i c i e n t s were v e r y low. Thus, on a b r o a d scale, even though s e v e r a l environmental f a c t o r s s i g n i f i c a n t l y affecting the abundance of sculpins have been ident i f i e d , by f a r the greatest amount of v a r i a b i l i t y in numbers is unexplained. It cannot be a s c e r t a i n e d at this point whether sampling e r r o r s , a v e r y patchy spatial d i s t r i b u t i o n of the f i s h even within homogenous habitat, or some highly important unidentified environmental v a r i a b l e s are r e s p o n s i b l e f o r the low p r e d i c t i v e power of the equations derived. (2) L o c a l i z e d F i s h D i s t r i b u t i o n s Section S eining and e l e c t r o - f i s h i n g data provide insight into the d i s t r i b u t i o n and abundance of C. a s p e r and C. aleuticus within a rather 35 l o c a l i z e d a r e a of favourable habitat. The environmental f a c t o r s c o n s i d e r e d f o r a l l analyses were velocity, substrate, depth, cover, month and time of day. Month and distance f r o m the mouth of the str e a m were el i m i n a t e d f r o m the analyses as the sampling p e r i o d was short ( 3 months) and the sampling sections were in close p r o x i m i t y to one another and a constant distance f r o m the stream mouth. i The time of day v a r i a b l e was included because the e f f i c i e n c y of the c o l l e c t i n g gear was thought to d i f f e r i n daylight and darkness. Two different methods of sampling the test sections were employed; the data are s u m m a r i z e d both separately and combined by method, within sections. The following is a, l i s t of Section A n a l y s e s : A n a l y s i s (I) Combined seining and e l e c t r o - f i s h i n g data, Section A ' A n a l y s i s (II) Seining data, Section A A n a l y s i s (III) E l e c t r o - f i s h i n g data, Section A A n a l y s i s (IV) Combined seining and e l e c t r o - f i s h i n g data, Section B . A n a l y s i s (V) Seining data, Section B A n a l y s i s (VI) E l e c t r o - f i s h i n g data, Section B Mu l t i p l e R e g r e s s i o n A n a l y s e s ( I ) to (VI) Seining and e l e c t r o - f i s h i n g r e s u l t s c o n s i d e r e d s e p a r a t e l y and com-bined f o r Sections A and B ge n e r a l l y indicate that C. a s p e r (total number and adults) were best p r e d i c t e d by the depth p a r a m e t e r while C. aleuticus (total number, y e a r l i n g and adults) were best p r e d i c t e d by the substrate 36 p a r a m e t e r (Table VI). Only in A n a l y s i s (II) did some fa c t o r other than substrate have the l a r g e s t standard p a r t i a l r e g r e s s i o n coefficient and hence r e p r e s e n t the best p r e d i c t o r f or total number of C. aleuticus. F r o m the signs of the r e g r e s s i o n coe f f i c i e n t s i n Table VI ( A n a l y s i s I) it can be seen that C. asper are more abundant in deep than i n shallow waters (total number and adults). Cottus aleuticus are m o r e abundant in in c o a r s e than in fine substrate (total number, y e a r l i n g s , and adults); m o r e abundant in deep than shallow water (total number, y e a r l i n g s and adults); l e s s abundant in fast water than slow (total number and y e a r l i n g s ) ; and, m o r e abundant at night than during the day. The r a t i o of the number of C. a s p e r to C. aleuticus d e c r e a s e s as the size of the substrate i n c r e a s e s . In A n a l y s e s (II) to (VI) the same general pattern as above p e r s i s t s f o r the m e a s u r e s of abundance of C. aleuticus and C. asper. The appearance of C. aleuticus in slow and deep water (flats and pools) may be a r e f l e c t i o n of d e c r e a s e d C. a s p e r i n the middle section of the r i v e r , thus allowing C. aleuticus to occupy a wider range of habitats than it n o r m a l l y does when C. asper is m o r e abundant. It must be r e m e m b e r e d that these data r e f l e c t l o c a l i z e d , not streamwide, d i s t r i b u t i o n a l patterns. In contrast to the B l o c k Seining analyses, some high values were obtained f o r m u l t i p l e c o r r e l a t i o n c o e f f i c i e n t s i n the Section Sampling A n a l y s e s (Appendix VI). F r o m 14 to 68 p e r cent of the v a r i a b i l i t y in abundance of the v a r i o u s groups of sculpins within this r e s t r i c t e d a r e a of ) the r i v e r was accounted f o r by the different sets of independent v a r i a b l e s used. T A B L E V I S u m m a r y of s i g n i f i c a n t s t a n d a r d p a r t i a l r e g r e s s i o n c o e f f i c i e n t s f o r S e c t i o n S e i n i n g a n d e l e c t r o - f i s h i n g d a t a ( l o c a l f i s h d i s t r i b u t i o n ) , S e c t i o n s A a n d B , A u g u s t t o O c t o b e r , 1965 . A s t e r i s k (*) i n d i c a t e s P < 0 . 0 5 ; a l l o t h e r v a l u e s P < 0 . 0 1 (**). D e s c r i p t i o n o f m u l t i p l e r e g r e s s i o n a n a l y s e s g i v e n o n p a g e 3 5 . t Species and age c l a s s M u l t i p l e R e g r e s s i o n A n a l y s e s S E C T I O N A D A T A S E C T I O N B D A T A Significant Seine and Seine data Shocker Seine and Seine data Shocker independent shocker data only data only shocker data only data only v a r i a b l e s (X) a n a l y s i s (I) A n a l y s i s (II): A n a l y s i s (III) A n a l y s i s (IV) A n a l y s i s (V) A n a l y s i s (VI) T o t a l C. a s p e r Substrate Depth 0.480=! 0.458** 1.037** 1.368=1 0.898** Adult C. a s p e r _ T o t a l C. aleuticus 10 i — i •s • .H U > £ Y e a r l i n g C. aleuticus a ; <x Q A d u l t C. aleutic u s Substrate Depth Substrate Depth V e l o c i t y T i m e ' (day-night) Month Substrate Depth V e l o c i t y T i m e (day-night) Substrate Depth V e l o c i t y T i m e (day-night) Month 0.495* 0.716** 0.620** •0.389* • 0.321* 0.648** 0.605** -0.378* 0.677** 0.530** -0.361* 0.600*" 0.734* 0.546* 0.605*: 0.587** 0.799** 0.970** 0.558* • 0.648** 0.841* 0.643* 0.928** -0.702** 0.475** 1.039** 0.747** -0.505** 0.801** 0.239* 0.558** •0.468* 1.359** 0.802* •0.352** 0.703** 0.770* 0.898** 0.956** 1.051** 0.702* -0.400* Ratio Substrate Depth -0.361 = 0.697** 38 P o p u l a t i o n E s t i m a t e s P o p u l a t i o n estimates f o r sculpins in Sections A and B were conducted in m i d - J u l y and late October, 1965 (Table VII). In study sections a p p r o x i -m a t e l y 1Z5 m long and 6 m wide, and c o m p r i s e d of r i f f l e - p o o l complexes, some 400-800 C. aleuticus and 30-200 C. asper were estimated to be present, f o r an average density of 0.74 C. aleuticus p e r square m e t e r and 0.10 C. a s p e r p e r square meter. In estimating populations i t was noted that C. aleuticus r a r e l y o c c u r r e d over fine substrate and C. asper were never taken in c u r r e n t areas. Thus, most of the C. aleuticus occupied only the p a r t of the sections c h a r a c t e r i z e d by c o a r s e substrate, and the C. aspjer occupied only the areas of low current. The two species overlap in the s m a l l f r a c t i o n of the total a r e a which has low water v e l o c i t y and c o a r s e substrate. A v e r a g i n g over the two sections and two dates, population densities were 0.85 C. aleuticus per square m eter of c o a r s e substrate and 0.35 C. asper p e r square m e t e r of slow c u r r e n t habitat (see Appendix IV f o r areas of v a r i o u s habitat types). Cottus aleuticus were approximately 2.4 times m o re dense than C. asper in the habitat they occupied separately. M c L a r n e y (1964) found C. aleuticus densities to be 1.03 f i s h p e r square m e t e r in Sashin Creek, A l a s k a . C o n s e r v a t i v e estimates p l a c e d on C. aleuticus populations in B i g K i t o i Creek, A l a s k a , by Meehan and Sheridan (1966) indicated densities between 16.1 and 21.5 f i s h p e r square m e t e r in an a r e a 305 m long and 6.1 m wide. 39 T A B L E V I I P o p u l a t i o n e s t i m a t e s o f C o t t u s a l e u t i c u s a n d C . a s p e r , S e c t i o n s A a n d B , L i t t l e C a m p b e l l R i v e r , W h i t e R o c k , B . C . C o t t u s a l e u t i c u s C o t t u s a s p e r J u l y 15 J u l y 18 O c t o b e r 24 O c t o b e r 30 M a r k e d ( M ) = 188 R e c a p t u r e ( C ) = 178 R e c a p t u r e m a r k e d (R) = 41 P o p u l a t i o n e s t i m a t e (N) = 801 M = C = R = N = 159 127 27 7 0 4 M C R M C R N 35 16 2 N =198 S E C T I O N A 27 9 3 68 J u l y 15 O c t o b e r 24 O c t o b e r 30 M C R N M C R N 103 141 22 635 119 119 32 433 M C R N M C R N 9 10 2 33 13 12 2 56 S E C T I O N B 40 F i s h A s s o c i a t i o n s Cottus aleuticus were prevalent as y e a r l i n g s and adults in the high gradient p o r t i o n of the stream, as f r y in the lower r i v e r and v i r t u a l l y absent f r o m the upper r i v e r . Cottus a s p e r of a l l age groups were most abundant in the lower r i v e r and d e c r e a s e d in abundance upstream except for a few l a r g e adult f i s h which inhabited pools of the upper r i v e r . F r y and y e a r l i n g C. aspe were found only i n the lower r i v e r . The number of C. aleuticus - C. asper a s s o c i a t i o n s d e c r e a s e d f r o m mouth to source because of concomitantly i n c r e a s i n g abundance of C. aleuticus and d e c r e a s i n g abundance of C. a s p e r (fig. 15). Cottus aleuticus were most often a s s o c i a t e d with Salmo g a i r d n e r i i (Table VIII) in r i f f l e areas while C. a s p e r were most highly a s s o c i a t e d with Oncorhynchus k i s u t c h (Table VIII) in pool environments. A s p e c t s of D i e l and Seasonal Movement Observations of day and night d i s t r i b u t i o n s at v a r i o u s stations indicate that adult sculpins which move do so almost e x c l u s i v e l y at night. Results f r o m two s e r i e s of day-night c o l l e c t i o n s i n Section C demonstrate a nocturnal movement of adult C. asper. Cottus a s p e r was l i m i t e d to deep water (pools) during daylight but did move into intermediate depths (flats) d u ring darkness (fig. 16). No consistent t r e n d in movement was noted f o r C. aleuticus although they became m o r e c l o s e l y a s s o c i a t e d with C. a s p e r d u r i n g darkness i n fla t s and pools. The number of C. aleuticus - C. a s p e r 41 100 90 80 LU O 21 70 UJ cc j§ 60 o O 50 £ 40 UJ o a: 30 UJ Q_ 20 10 O COTTUS ALEUTICUS O C. ALEUTICUS , C. ASPER • COTTUS ASPER F i g . 15. P e r c e n t o c c u r r e n c e , a n d n u m b e r ( p a r e n t h e s e s ) o f c o l l e c t i o n s i n w h i c h C . a l e u t i c u s a n d C . a s p e r w e r e f o u n d a l o n e a n d i n a s s o c i a t i o n , A u g u s t t o O c t o b e r , 1965 , L i t t l e C a m p b e l l R i v e r . T A B L E VIII T o t a l and approximate p e r cent o c c u r r e n c e c o f f i s h taken i n 205 coll e c t i o n s containing C. aleuticus and 244 co l l e c t i o n s containing C. asper. S almo g a i r d n e r i i One orhynchus k i s u t c h  Cottus a s p e r Cottus aleuticus G a s t e r o s t e u s aculeatus Leptocottus armatus P l a t i c h t h y s stellatus O t h ers (Gobies, Pholids) Salmo c l a r k i i c l a r k i i C linocottus acuticeps  Oligocottus maculosus None Catostomus catostomus  Oneorhynchus keta C O T T U S A L E U T I C U S T o t a l O c c u r r e n c e 94 72 69 33 22 15 16 12 11 7 11 App r oxim ate P e r cent O c c u r r e n c e 46 35 34 16 11 8 8 6 5 3 5 C O T T U S A S P E R T o t a l O c c u r r e n c e 3 3 9 3 6 9 75 47 32 2 9 10 11 11 6 4 4 Approximate P e r cent O c c u r r e n c e 13 38 28 31 19 13 12 4 5 5 2 2 2 IN) 43 3 < 1 2 LU £= I LU CO or LU 0_ 4 X OO 3 U . 2 or i LU CD LU < or LU > < 3 -COTTUS ALEUTICUS COTTUS ASPER 0900 HRS. ±X_ X I 1600 HRS. J_x_ 2200 HRS RIFFLE I RUN I FLAT DEPTH DISTRIBUTION POOL F i g . 16. A v e r a g e n u m b e r of f i s h p e r s e i n e h a u l i n a r i f f l e - r u n -f l a t - p o o l c o m p l e x , S e c t i o n C , L i t t l e C a m p b e l l R i v e r . D a t a r e p r e s e n t s 53 d a y a n d 61 n i g h t c o l l e c t i o n s t a k e n S e p t e m b e r 3 a n d O c t o b e r 10, 1 9 6 5 . L i m i t s of h a b i t a t d e p t h s i n d i c a t e d i n A p p e n d i x V . A l l f i s h r e t u r n e d t o s i t e of c a p t u r e . 44 a s s o c i a t i o n s i n c r e a s e d during darkness (fig. 17). The d i u r n a l o c c u r r e n c e of food o r g a n i s m s in the stomach and intes t i n a l t r a c t of sculpins i n L i t t l e C a m p b e l l R i v e r was investigated by examination of 160 C. aleuticus and 20 C. asper f r o m day and night c o l l e c t i o n s on October 11, 1965. R e g a r d l e s s of habitat occupied, f i s h captured at night had 35 p e r cent m o r e of the i n t e s t i n a l t r a c t f i l l e d with food, an 86 p e r cent g r e a t e r stomach weight and a 24 p e r cent g r e a t e r stomach to in t e s t i n a l t r a c t weight ra t i o than did f i s h caught during the day (Table IX). Cottus aleuticus and C. as p e r appear to feed p r i n c i p a l l y during darkness, feeding being a s s o c i a t e d with the nocturnal movements noted above. Short t e r m change in habitat quality can allow species r e d i s t r i b u t i o n to occur. Summer t i d a l depth effects of a meter, r e v e r s a l of flow d i r e c t i o n twice d a i l y and concomitant reduced v e l o c i t i e s affect s c u l p i n f r y d i s t r i b u t i o n at Station 4. Cottus asper f r y r a r e l y occupy r i f f l e habitats whereas C. aleuticus .can and do occupy vegetated f l a t s . When r i f f l e habitats are ti d a l l y inundated they become e s s e n t i a l l y pool habitats and C. asper f r y occupy these a r e a s with C. aleuticus f r y (fig. 18). Co l l e c t i o n s in, above, between and below Sections A and B indicated that the m a j o r i t y of m a r k e d f i s h r e c a p t u r e d had re m a i n e d within 120 m of rel e a s e point. M o s t f i s h were r e c a p t u r e d within 15 m of rel e a s e point during the f i r s t month after r e l e a s e and some f i s h were s t i l l within the above l i m i t s after 9 months (fig. 19). T h e r e was no apparent d i r e c t i o n a l i t y of movement, but there was a tendency f o r f i s h to be reca p t u r e d at gr e a t e r 4 5 L U O L U en ZD O o o L U O OC L U CL C. A L E U T l C U S - C . A S P E R C. A L E U T I C U S C A S P E R A S S O C I A T I O N S O C C U R R I N G A L O N E O C C U R R I N G A L O N E F i g . 1 7 . P e r c e n t o c c u r r e n c e a n d n u m b e r ( p a r e n t h e s e s ) o f 5 3 d a y a n d 61 n i g h t c o l l e c t i o n s i n w h i c h C . a l e u t i c u s a n d C . a s p e r w e r e f o u n d a l o n e a n d i n a s s o c i a t i o n . D a t a c o m b i n e d f o r S e p t e m b e r 3 a n d O c t o b e r 10, 1 9 6 5 . 46 T A B L E IX Summary of average p e r cent int e s t i n a l t r a c t occupied (A), weight of stomach contents (B) and Ratio of stomach to in t e s t i n a l t r a c t weight (C) in day and night-captured C. aleuticus and C. asper f r o m different habitats i n Section B, October 11, 1965. Sample s i z e s i n parentheses. • A. P e r cent of i n t e s t i n a l t r a c t occupied. C. aleuticus C. as p e r R i f f 1 e Day R i f f l e 38(40) -P o o l 40(40) 54(10) Ri f f l e . 62(40) -P o o l 71(40) 71(10) Night B. Weight of stomach contents (gm) C. aleuticus C. asper Day R i f f l e 0.058 -P o o l 0.044 0.086 R i f f l e 0.152 -P o o l . 0.496 0.711 C. Ratio of stomach to in t e s t i n a l t r a c t weight Day Night C. aleuticus C. asper R i f f l e 1.40 -P o o l 1.40 1.40 Ri f f l e 1.53 -P o o l 2.15 1.97 47 125 r-X ¥1 100 LL. 7 5 O R O a: UJ 50 QQ 2 , => 25 Z 0 (76) FLAT 1 1 COTTUS ALEUTICUS IHIJ COTTUS ASPER 0930 HRS. AUGUST 12,1965 95) (5) RIFFLE DIRECTION OF FLOW [ > LOW TIDE 125 r-X to 100 O F 0 BL UJ 50 CD ZD 25 1830 HRS. AUGUST 12,1965 (37) (63) POOL POOL DIRECTION OF FLOW HIGH TIDE F i g . 18. T i d a l depth influence on dis t r i b u t i o n s of C. aleuticus and C. as p e r f r y , Station 4, L i t t l e Campbell Ri v e r . P e r c e n t o c c u r r e n c e of species i n v a r i o u s habitats indicated in parentheses. 48 2 5 0 -2 0 0 -150 -100-5 0 -X CO CO or LU 10 8 6 4 2 0 8 6 4 2 0 6 4 2 0 4 2 0 •212 •24 I 1 COTTUS ALEUTICUS COTTUS ASPER SEPTEMBER 26,1965 OCTOBER 10,1965 n OCTOBER 23, 1965 Q OCTOBER 30,1965 JUNE 16, 1966 60- 30- + 30 + 60 DISTANCE IN METERS F i g . 19. N u m b e r a n d p o s i t i o n of s c u l p i n s s u b s e q u e n t to i n i t i a l r e l e a s e of 212 C . a l e u t i c u s a n d 24 C . a s p e r at 0 m e t e r m a r k . A l l s a m p l e s r e m o v e d f r o m tes t s e c t i o n on s a m p l i n g - d a t e s i n d i c a t e d . D i r e c t i o n of w a t e r f l o w f r o m +60 m to -60 m . 49 distance f r o m the r e l e a s e point with i n c r e a s i n g time. Cottus aleuticus r e l e a s e d in pools were subsequently found in g r e a t e r numbers in non-pool habitats while C. a s p e r l i b e r a t e d i n r i f f l e s subsequently occupied areas of. non-current. Of 3723 f i s h captured in Sections A, B and C f r o m July 17, 1965, to i • June 16, 1966, some 1604 were m a r k e d (1437 C. aleuticus, 167 C. asper) and 486 subsequently recaptured. Only 20 f i s h of the 1604 m a r k e d were re c a p t u r e d outside o r i g i n a l areas of c o l l e c t i o n and r e l e a s e . F o u r f i s h moved ups t r e a m between 300 m and 425 m while 16 f i s h moved downstream between 75 m and 580 m. E x t e n s i v e sampling outside the approximate 600 m length of s t r e a m c o v e r e d by Sections A, B and C r e c o v e r e d no m a r k e d f i s h . M o s t C. asper inhabiting the lower r i v e r m i g r a t e to the estuary of the L i t t l e C a m p b e l l R i v e r to spawn in A p r i l and May. K r e j s a (1965) indicated that C. asper m i g r a t e d at l e a s t 4 m i l e s (6.4 km) downstream to spawn during M a r c h , A p r i l and May. Studies in 1966 r e v e a l e d that C. asper were a l s o spawning i n the middle p o r t i o n of the s t r e a m in clos e p r o x i m i t y to spawning C. aleuticus. Cottus aleuticus i s not known to spawn i n the estuarine p o r t i o n of the stream. Cottus aleuticus may show l o c a l i z e d movement f o r spawning sites i n the middle, high gradient p o r t i o n of the stream. A l l f r y of both species occupy the upper estuarine p o r t i o n of the stream, p a r t i c u l a r l y around Stations 4, 5 and 6. A s y e a r l i n g s both 50 species of sculpins move upstream; C. asper move l e s s than 6 km and C. aleuticus l e s s than 12 km. Cottus a s p e r adults are found higher up in drainage a r e a than C. aleuticus, moving at le a s t 16 km. M o s t C. aleuticus adults are located 6 to 12 km f r o m the stream mouth in the middle, high gradient section of the stream. R E S U L T S ( L A B O R A T O R Y STUDIES) F l o w and Substrate P r e f e r e n c e s (1) L a b o r a t o r y F i s h A T h i s lot of f i s h was brought d i r e c t l y to the l a b o r a t o r y f r o m the f i e l d and i m m e d i a t e l y subjected to tests of p r e f e r e n c e f o r c u r r e n t and substrate. Cottus aleuticus, l e s s than 40 mm long did not show a p r e f e r e n c e f o r either of the water v e l o c i t y choices; while those g r e a t e r than 40 mm selected c u r r e n t (fig. 20). A l l size groups of C. aleuticus p r e f e r r e d c o a r s e to fine substrate except the 85-90 mm group, which had no p r e f e r e n c e (fig. 20). When offered a simultaneous choice of water v e l o c i t y and substrate, C. aleuticus p r e f e r r e d the c u r r e n t and c o a r s e substrate combination (fig. 21). Cottus a s p e r l e s s than 40 mm long did not show a p r e f e r e n c e for either of the water v e l o c i t y conditions; f i s h between 40 and 85 mm selected quiet water over current; and f i s h in the 85-90 mm group showed no p r e f e r e n c e (fig. 22). Cottus asper l e s s than 40 mm long p r e f e r r e d c o a r s e substrate, while f i s h of l a r g e r size had no p r e f e r e n c e . When offer e d a simultaneous choice of water v e l o c i t y and substrate, C. a s p e r showed no 51 COTTUS ALEUTICUS 100 8 0 6 0 4 0 2 0 CURRENT 6 E E E E E ~io O in CVJ 1 CD 1 o 1 in 6 ro CD 2 0 -4 0 -6 0 -8 0 -100 E E O I m oo E £ o o NON-CURRENT COARSE SUBSTRATE E E in CVJ i o CM E E O I in ro E E to CD I O CD E E O 0> m oo co U J o UJ 0_ FINE SUBSTRATE F i g . 20. A p p r o x i m a t e percent o c c u r r e n c e of Q aleuticus ( L a b o r a t o r y F i s h A) i n c u r r e n t and non-current channels and o c c u r r e n c e o v e r c o a r s e and fine substrates. T e s t s f o r flow and substrate p r e f e r e n c e s p e r f o r m e d separately. / \ 52 C O T T U S A L E U T I C U S 100 8 0 60 UJ cr U u o z LU u ct UJ CL CURRENT © 2 0 E - E o i in 2 0 -4 0 6 0 8 0 IOO E E E E XT) o | o o IT) vO 00 N O N -CURRENT 1 C O A R S E SUBSTRATE E E o I in E E in vO i O o E E o o-i in CO E E o in ro E E in • O E E o o i in CO FINE SUBSTRATE F i g . 21. Approximate per c e n t o c c u r r e n c e of C. aleuticus ( L a b o r a t o r y F i s h A) i n c u r r e n t and non-current channels and o c c u r r e n c e o v e r c o a r s e and fine substrates within channels 1 and 2. T e s t s f o r flow and substrate p r e f e r e n c e s p e r f o r m e d simultaneously. C O T T U S A S P E R 1 0 0 80 60 40 20 20 40 6O 80 IOO CURRENT E E if) CM I o CM E E o I in CO E E in o 1 O o E E o o 1 in 00 in O _1 0 . E E o NON-CURRENT COARSE SUBSTRATE E E in CM 1 O CM E E o 1 m CO E E in 1 O o E E o o 1 in CO • if) z> _i a E E o FINE SUBSTRATE F i g . 22. Approximate percent o c c u r r e n c e of C. as p e r ( L a b o r a t o r y F i s h A) in c u r r e n t and non-current channel and o c c u r r e n c e over c o a r s e and fine substrates. T e s t s f o r flow and substrate p r e f e r e n c e s p e r f o r m e d separately. 54 p r e f e r e n c e f o r either of the v e l o c i t i e s . F o r those f i s h which entered the quiet water channel, those i n the 85-90 mm group showed a p r e f e r e n c e fo r fine substrate, while no p r e f e r e n c e was shown by f i s h of the other size groups (fig. 23). The data f o r this s e r i e s of experiments are s u m m a r i z e d in T a b l e s X to XII. Res u l t s of p r e f e r e n c e testing f o r additional size groups are s u m m a r i z e d i n Appendix VII. (.2) L a b o r a t o r y F i s h B F i s h held i n bare troughs at water l e v e l s of 22 cm and a ve l o c i t y of 7.5 cm/sec f o r 60 days before testing showed p r e f e r e n c e s f o r water v e l o c i t y and substrate g e n e r a l l y c o r r e s p o n d i n g to r e s u l t s obtained f o r f i s h tested d i r e c t l y f r o m the f i e l d . The one notable exception was a non-current s e l e c t i o n by 35-40 mm C. asper. The l a c k of habitat, i n the f o r m of flow and substrate conditions, did not g e n e r a l l y affect a species choice of water ve l o c i t y or substrate type. T a b l e s XIII and XIV s u m m a r i z e the r e s u l t s of the sequential tests (Cole, 1962) and other tests p e r f o r m e d on this group of l a b o r a t o r y - h e l d f i s h . (3) L a b o r a t o r y F i s h C Bef o r e testing, these f i s h were held i n the l a b o r a t o r y f o r 60 days under a r t i f i c i a l conditions designed to simulate high or low water v e l o c i t i e s i n combination with c o a r s e or fine substrates, s i m i l a r to those encountered i n the L i t t l e C a m p b e l l R i v e r . The purpose of this e xperiment was to note the response of the species to flow conditions 55 C O T T U S A S P E R 100 80 60 UJ U 40 z UJ Ct ct 20 z> u 8 o h-Z U J 20 U Ct UJ Q. 40 CURRENT \- © E E O in ro 60 -8O -E E in 1 O E E o o 1 in CO IOO tn Q. E E o N O N -CURRENT 2 COARSE SUBSTRATE •.. • •1 • • E E o I in ro E E in 1 O o T77T E E o o 1 in CO <n _J Q. E E ii 1':::: E E o I in ro © E E m o 1 O E E o o 1 in CO m _ l Q. E E o FINE SUBSTRATE F i g . 23. Approximate percent o c c u r r e n c e of C. asper ( L a b o r a t o r y F i s h A) i n c u r r e n t and non-current channels and o c c u r r e n c e o v e r c o a r s e and fine substrates within channels 1 and 2. T e s t s f o r flow and substrate p r e f e r e n c e s p e r f o r m e d s imultan e ous ly. T A B L E X Summary of c u r r e n t and non-current p r e f e r e n c e s f o r L a b o r a t o r y F i s h A. Results s u m m a r i z e d f r o m sequential test design a n a l y s i s (Cole, 1962)*. Approximate p e r cent given i n parentheses. S p e c i e s Size (mm) No. obs. No choice T o t a l F i s h Flow-C u r r e n t N o n - c u r r e n t R e s u l t s * C. aleutic u s 20-25 16 1 15 8(54) 7(46) No p r e f e r e n c e 35-40 21 1 20 8(40) 12(60) No p r e f e r e n c e 60-65 21 0 21 17(81) 4(19) C u r r e n t 85-90 48 12 60 39(85) 9(15) C u r r e n t 110 + 7 0 7 7(100) 0(0) C u r r e n t C. a s p e r 20-25 23 0 23 9(39) 14(61) No p r e f e r e n c e 35-40 18 3 15 7(47) 8(53) No p r e f e r e n c e 60-65 20 0 20 4(20) 16(80) Non - c u r r e n t 85-90 12 2 10 1(10) 9(90) Non - c u r r e n t 57 T A B L E XI Summary of c o a r s e and fine substrate p r e f e r e n c e f o r L a b o r a t o r y F i s h A. Approximate p e r cent o c c u r r e n c e given i n parentheses. T o t a l Substrate Species Size (mm) No. Obs. No. F i s h F i s h C o a r s e F i n e C. aleuticus 20-25 9 15 135 106(78) 29(22) 35-40 9 15 135 104(77) 31(23) 60-65 14 15 210 133(64) 77(36) 85-90 16 15 240 136(56) 104(44) C. a s p e r 20-25 15 15 225 164(73) 61(27) 35-40 12 15 180 149(79) 31(21) 60-65 12 15 180 88(49) 92(51) 85-90 12 15 180 76(42) 104(58) 110 + 13 15 195 82(42) 113(58) T A B L E XII Summary of simultaneous choice of flow and substrate conditions by_C_. aleuticus and C. a s p e r ( L a b o r a t o r y F i s h A). Approximate p e r cent o c c u r r e n c e given i n parentheses. S i z e T o t a l M i s s i n g F l o w * C u r r e n t N o n - c u r r e n t Species (mm) No. Obs. No. f i s h F i s h f i s h C u r r e n t Non-current C o a r s e F i n e C o a r s e F i n e C. aleuticus 35-40. , 13 15 195 8 137(73) 50(27) 130(95) 7(5) 35(70) 15(30) 60-65 11 15 165 3 100(62) 62(38) 69(69) 3^1(31) 54(87) 8(13) 85-90 29 15 435 13 267(63) 155(37) 167(63) 100(37)117(75) 38(25) C. a s p e r 35-40 22 15 330 4 141(43) 185(57) 75(53) 66(47) 117(63) 68(37) 6.0-65 10 15 150 7 68(48) 75(52) 38(57) 29(43) 30(39) 46(61) 85-90 10 15 150 5 ; 63(53) 82(47) 40(63) 23(37) 21(26) 60(74) 100 + 16 15 240 5 105(31) 130(69) 56(53) 49(47) 60(46) 70(54) Ui 00 T A B L E XIII Summary of c u r r e n t and non-current p r e f e r e n c e f o r L a b o r a t o r y F i s h B. Results s u m m a r i z e d f r o m sequential test design a n a l y s i s (Cole, 1962)*. Approximate p e r cent given i n parentheses. Species Size (mm) No. Obs. No Choice T o t a l F i s h F l o w C u r r e n t Non-C. Results C. aleuticus 35-40 15 2 13 6(46) 7(54) No p r e f e r e n c e 60-65 21 - 21 17(81) 4(19) C u r r e n t 85-90 15 - 15 12(80) 3(20) C u r r e n t C. asper 35-40 18 - 18 3(17) 15(83) Non - c u r r e n t 60-65 12 - 12 2(17) 10(83) Non - c u r r e n t 85-90 21 3 18 7(39) 11(61) No p r e f e r e n c e 110 + 12 2 10 1(10) 9(90) Non-current 60 T A B L E XIV Summary of c o a r s e and fine substrate p r e f e r e n c e f o r L a b o r a t o r y F i s h B. Approximate p e r cent o c c u r r e n c e given in parentheses. T o t a l Substrate Species Size (mm) No. Obs. No. F i s h F i s h C o a r s e F i n e C. aleuticus 35-40 8 15 120 84(71) 36(29) 60-65 8 15 120 90(75) 30(25) 85-90 8 15 120 73(61) 27(39) C. a s p e r 35-40 8 15 120 97(81) 23(19) 60-65 8 15 120 69 ( 58)[ 31(42) 85-90 8 15 120 62(52) 38(48) ldtj + 8 15 120 55(46) 65(54) 61 after being h e l d i n habitat conditions i n which they never or r a r e l y o c c u r r e d i n nature. The experiment was l a i d out in a f a c t o r i a l design, with two species, two age groups (actually size groups, suggested by length-frequency analysis to c o r r e s p o n d to " y e a r l i n g f i s h " , and a group of m i x e d older f i s h r e f e r r e d to as "adults"), two different substrates to which f i s h were exposed f o r 60 days, two dif f e r e n t water v e l o c i t i e s to which f i s h were exposed f o r 60 days, and 5 r e p l i c a t e s ( c o n s i s t i n g of in d i v i d u a l fish). The water v e l o c i t y choice was s c o r e d at the end of 3 second, again at 30 seconds, and a t h i r d time at 15 minutes. It became obvious that the f i s h had not had a sufficient time to i become settled by the f i r s t observation time; the outcome of a t r i a l was u s u a l l y the same at the second and t h i r d observation times. A s the three sets of data are not independent, the r e s u l t s given here are based on the t h i r d o b s e r vation time, (Appendix VIII). Of the m a i n effects, only that f o r species was significant (P<0.1) . Cottus aleuticus tended to choose high water v e l o c i t y and C. a s p e r tended to choose low v e l o c i t y or to r e m a i n i n the s m a l l a r e a of the experimental apparatus where f i r s t introduced. T h i s s m a l l a r e a was m o r e li k e the low vel o c i t y channel than the high. A f i s h was given a sc o r e of 1 if it chose curre n t , and a sc o r e of 0 if it chose quiet water or f a i l e d to make a choice. Thus, if half the f i s h of a group chose c u r r e n t and half did not, th e i r average score would be 0.5. The average s c o r e f o r C. aleuticus was 0.650 and, f o r C. asper, was 0.325. 62 Of p a r t i c u l a r a p r i o r i i n t e r e s t were the f i r s t o r d e r i n t e r a c t i o n s , species X water v e l o c i t y holding conditions, and species X substrate holding conditions. However, there was no significant d i f f e r e n t i a l response to holding conditions by the two species, nor was there any response to holding conditions by both species combined. The second o r d e r i n t e r a c t i o n s , species X substrate holding conditions X water v e l o c i t y conditions and species X substrate holding conditions X age were sig n i f i c a n t at the 0.05 p r o b a b i l i t y l e v e l . The f i r s t of these a r i s e s f r o m the tendency f o r C. aleuticus held before testing over fine substrate in c u r r e n t or over c o a r s e substrate i n quiet water to choose c u r r e n t m o re frequently than f i s h of the same species held over fine substrate in quiet water or over c o a r s e substrate i n c u r r e n t , while f o r C. asper, the g r e a t e r tendency to choose c u r r e n t i s found i n f i s h held over fine substrate i n quiet water or over c o a r s e substrate i n current. The second si g n i f i c a n t second-o r d e r i n t e r a c t i o n r e f l e c t s the tendency f o r y e a r l i n g C. aleuticus held over fine substrate to choose c u r r e n t i n p r e f e r e n c e to quiet water m ore frequently than adults held over fine substrate or than either age held over c o a r s e substrate, while f o r C. asper, the most frequent choice of c u r r e n t is by adults held over fine substrate. These d i f f e r e n t i a l responses f are c a n c e l l e d out when data are averaged over the two l e v e l s of one or two or the f a c t o r s involved; hence, no f i r s t o r d e r i n t e r a c t i o n s or m a i n effects, aside f r o m that f o r species, are significant. 63 S U M M A R Y O F R E S U L T S F i e l d observations r e v e a l e d d i f f e r e n c e s i n the d i s t r i b u t i o n and abundance of different size groups of C. aleuticus and C. asper to be attributable to v a r i a t i o n s i n water velocity, substrate, depth and cover. The following points emerge: 1. Cottus aleuticus are found p r i n c i p a l l y i n a r e a s of c u r r e n t although l a r g e i n d i v i d u a l s may inhabit pool areas with C. asper. Cottus a s p e r are r a r e l y found in areas of c u r r e n t . 2. Cottus aleuticus are r a r e l y found over fine-textured substrates; C. a s p e r are found over a wide v a r i e t y of substrate types. 3. Cottus aleuticus and C. asper are l a r g e l y segregated into different m i c r o h a b i t a t s during daylight but may occupy s i m i l a r a r e a s during darkness. 4. Cottus asper are m a i n l y estuarine spawners while C. aleuticus ' spawn e n t i r e l y in freshwater. Some C. a s p e r were observed to spawn i n f r e s h w a t e r in the same habitat as C. aleuticus. 5. Occupation of only the lower reaches of the L i t t l e C a m p b e ll R i v e r by f r y of the two species suggests a downstream passage by pelagic l a r v a e of n e a r l y a l l C. aleuticus ( a l l of which are spawned upstream) and those C. a s p e r which are spawned ups t r e a m of the estuary. 6. Cottus aleuticus d i s p e r s e upstream as y e a r l i n g s i n g r e a t e r numbers than C. asper. Habitat segregation is most pronounced 64 in f i s h between 40 and 80 mm long. 7. In stre a m sections, approximately 125 m long and 6 m wide, some 400 to 800 C. aleuticus and 30 to 200 C. a s p e r were estimated to be present. Average densities f o r J u l y and October, 1965 were 0.85 f i s h / s q . m e t e r f o r C. aleuticus, and 0.35 f i s h / s q . m e t e r f o r C. asper. 8. Adult C. as p e r often move f r o m deep to shallower waters during darkness. 9. Cottus aleuticus and C. as p e r are p r i n c i p a l l y nocturnal feeders. 10. Cottus aleuticus are most often a s s o c i a t e d with S. g a i r d n e r i i i n r i f f l e s while C. as p e r are most often a s s o c i a t e d with O. k i s u t c h i n pools. 11. M a r k and recapture of some 500 sculpins i n the middle section of the stre a m indicated f i s h to be r e l a t i v e l y r e s t r i c t e d i n move-ment between June and October (low water period). M o s t f i s h were reca p t u r e d within 120 m of r e l e a s e point with only a few f a r t h e r than 300 m. Some recognizable individuals were within 5 m of r e l e a s e point after 9 months. L a b o r a t o r y experiments tested the different response of the sc\ilpins to water v e l o c i t y and substrate type. The following points emerge: 1. L a b o r a t o r y experiments show C. aleuticus to p r e f e r c o a r s e substrate and c u r r e n t while C. as p e r show no substrate p r e f e r e n c e and g e n e r a l l y selects quiet water over current. 65 2. The l a c k of habitat conditions and a l s o the p r e sence of habitat conditions (flow and substrate) during a 60 day holding p e r i o d did not appear to a l t e r a s p e c i e s 1 response when compared to f i s h tested d i r e c t l y f r o m the f i e l d . T h ese r e s u l t s are only applicable to y e a r l i n g and adult f i s h . DISCUSSION A number of w o r k e r s f r o m C a l i f o r n i a to B r i t i s h C o l u m b i a have d e s c r i b e d downstream m i g r a t i o n of sculpins to estuarine a r e a s during spawning p e r i o d s (Hunter, 1959; Shapovalov and Taft, 1954; K r e j s a , 1965 unpublished Ph.D.). M c A l l i s t e r and L i n d s e y (1959) indicated that, unlike the p r i n c i p a l l y estuarine-spawning populations of the L i t t l e C a m p b e l l R i v e r , C. a s p e r populations at H a t z i c Lake, B.C., some 50 m i l e s f r o m the sea, spawned in freshwater. Recently settled f r y (young-of-the-year) of both the coast range and p r i c k l y s c u l p i n were commonly captured in the r e l a t i v e l y slow and vegetated water a r e a s of the lower L i t t l e C a m p b e l l R i v e r . T h e r e appeared to be a divergence in habitat e a r l y in l i f e with some C. aleuticus f r y o c c u r r i n g i n c u r r e n t areas within weeks after settling, while C. asper were always most abundant in quiet water. B y the end of the f i r s t year, the two species showed almost complete habitat segregation. The p r e f e r e n c e of C. aleuticus f o r c o a r s e substrate and c u r r e n t and of C. asper f o r quiet water, as demonstrated i n the l a b o r a t o r y , account f o r much of the d i f f e r e n c e i n the d i s t r i b u t i o n of the species observed under na t u r a l 66 conditions in the L i t t l e C a m p b e l l R i v e r . A c c o r d i n g to Bond (1963) the general e c o l o g i c a l r e q u i r e m e n t s of the two sculpins appear to be s i m i l a r . Although sculpins Whow wide t o l e r a n c e s t y p i c a l of f r e s h w a t e r fishes ( L a r k i n , 1956), observations of the habitats of C. aleuticus and C. a s p e r show that p r e f e r e n c e is u s u a l l y indicated f o r s p e c i f i c conditions. Both biotic and abiotic f a c t o r s of the environment are p robably c o n t r o l l i n g s p a t i a l d i s t r i b u t i o n . Some species may be l i m i t e d by a high degree of s p e c i a l i z a t i o n to a r e s t r i c t e d habitat while l e s s s p e c i a l i z e d species can occupy a v a r i e t y of habitats left open by the m o re r e s t r i c t e d f o r m s . Involved in habitat s e l e c t i o n are r e q u i r e m e n t s for the following: flow, substrate, depth, cover, sufficient space to accommodate the i n d i v i d u a l f i s h , and spawning sites. Bond indicates such f a c t o r s as temperature and s a l i n i t y t olerance, oxygen consumption, tolerance of low oxygen and size and type of food accepted as being important in habitat selection. The c r y p t i c behaviour and need f o r stones and other cover are r e c o g n i z e d facets of s c u l p i n biology, (Bond, 1963). Cottus a s p e r which grow l a r g e r than C. aleuticus u l t i m a t e l y need l a r g e r habitats. It follows that as sculpins i n c r e a s e i n s i z e , so must the accommodating elements within habitats. The lower r i v e r , where a l l f r y of both species exist, contains a l i m i t e d amount of c o a r s e substrate and, with d e c r e a s i n g water l e v e l s i n late June, y e a r l i n g C. aleuticus are probably f o r c e d to m i g r a t e u p s t r e a m to l a r g e r substrate. Concomitant with d e c r e a s i n g water l e v e l s 67 a r e i n c r e a s i n g temperatures and it is p o s s i b l e that C. aleuticus r e q u i r e low temperature and i n c r e a s e d oxygen as y e a r l i n g s and adults. These conditions are found i n the steep gradient p o r t i o n of the stream. Cottus asper, which have a g r e a t e r s a l i n i t y tolerance, lower oxygen demand and a higher tolerance of warm temperatures (Bond, 1963) probably d i s p e r s e upstream in response to degree of habitat occupation i n the lower r i v e r . Cottus asper appear to be c l o s e l y a s s o c i a t e d with vegetative c o v e r in the l o w e r r i v e r r e g a r d l e s s of water depth. Only adults were found upstream of the lower r i v e r . The number of C. as p e r in the middle r i v e r i s probably a function of available pool habitat. Depth and rat i o of pools to r i f f l e s d e c r e a s e s upstream except f o r the upper r i v e r where pools predominate (Table I). The s m a l l number of C. as p e r (adults only) i n the upper r i v e r may be a res u l t of l i m i t e d passage upstream due to the s t r e a m becoming subterranean f o r six months of the year. Cottus aleuticus may avoid the upper r i v e r due o to e x c l u s i v e pool environments where temperatures are often 10 higher than the m i d d l e r i v e r and low oxygen concentrations are suggested by the not infrequent f i s h - k i l l s . Bond, (1963) indicated that sculpins avoided oxygen concentrations l e s s than 4 p.p.m. and succumbed at oxygen concen-tratio n s of about 1.5 p.p.m. C. as p e r were shown to have a lower r e s t i n g oxygen consumption than C. aleuticus i n two out of three temperatures tested (Bond). V a r i a t i o n s i n oxygen consumption between the species suggests d i f f e r e n t i a l a b i l i t i e s to occupy v a r i o u s habitats due to interactions between temperature and oxygen. In the L i t t l e C a m p b e l l R i v e r , _C_. aleuticus 68 and C. a s p e r f r y were found in areas of s i m i l a r temperature, while C. aleuticus adults were found only in temperatures l e s s than 15°. C. asper adults occupied areas with temperatures as high as 26.5°. In the lower r i v e r , C. aleuticus f r y occupied both pool and r i f f l e environments when C. asper were absent or s c a r c e . The subsequent appearance of G. a s p e r in pool environments was concomitant with i n c r e a s e d C. aleuticus i n r i f f l e environments. T h e r e i s some suggestion of i n t e r p e c i f i c competition f o r harborage sites. It i s not precluded, however, that h igher oxygen demands are a s s o c i a t e d with habitat occupation by C. aleuticus f r y . Cottus a s p e r o c c u r r e d over the wide v a r i e t y of substrate types in the f i e l d that are found i n n o n - c u r r e n t environments. Although C. a s p e r showed no f i e l d or l a b o r a t o r y p r e f e r e n c e f o r substrate, c o v e r for f r y in the f o r m of vegetation, and depth p r o v i d e d by pools for adults appear to be important in both b r o a d - s c a l e and l o c a l d i s t r i b u t i o n s . M i u r a (1962) stated that the s m a l l e s t individuals had a p r e f e r e n c e f o r yegetated a r e a s in N i c o l a Lake, B.C. Bond (1963) pointed out that the l a r g e s t individuals r e m a i ned in deep water, often hiding i n vegetation, although g e n e r a l l y the species sought concealment l e s s frequently than C. aleuticus. Intrageneric r e l a t i o n s h i p s r e v o l v i n g around one or m o re of the above-mentioned e c o l o g i c a l f a c t o r s involved in habitat s e l e c t i o n could tr a n s l a t e subtle e c o l o g i c a l l i m i t a t i o n s o r c a p a b i l i t i e s into obvious d i f f e r e n c e s in d i s t r i b u -tion. Species better adapted to s p e c i f i c habitats could p a r t l y or completely 69 d i s p l a c e the species l e s s w e l l adapted. P e r h a p s as Gee and Northcote (1963) have suggested near-complete habitat divergence allows two re l a t e d species, which o c c u r i n the same r i v e r areas, to exist without entering into severe competition f o r the e s s e n t i a l r e s o u r c e s of t h e i r environment. O b s e r v a t i o n of reproductive behaviour (not r e p o r t e d on) indicates that the two species have s i m i l a r spawning r e p e r t o i r e s and segregation is p a r t l y m aintained by se l e c t i o n of l a r g e r substrate by C. asper. Cottus asper may be m o r e a g g r e s s i v e than C. aleuticus and p o s s e s s a wider tolerance of e c o l o g i c a l conditions, hence it's w idespread appearance i n both co a s t a l and inland lakes and streams. Coactions among salmonids and sculpins could i n f l u e n c e d i s t r i b u t i o n of both groups. Salmo g a i r d n e r i i f r y , which occupy r i f f l e a r e a s with C. aleuticus during summer months, may be i n d i r e c t competition f o r l a r v a l aquatic food (G.R. P e t e r s o n , p e r s . comm.). T r o u t f r y m a y b e subject to predation by C. aleuticus but trout y e a r l i n g s are probably not p r e y e d upon due to size. H i d i n g behaviour by trout under winter conditions (Hartman, 1965) may have adaptive value i n protecting,.them f r o m " s c o u r i n g " and f r o m b i r d predation (Lindroth, 1955) but may b r i n g them into competition f o r harborage sites. Oncorhynchus k i s u t c h u n d e r y e a r l i n g s , which p r i m a r i l y occupy pool environments i n summer (Hartman, 1965) and feed p r i m a r i l y on t e r r e s t r i a l d r i f t (G.R. P e t e r s o n , p e r s . comm.), probably have l i t t l e i n t e r a c t i o n with either C. asper or l a r g e aleuticus inhabiting pools. 70 With p o s s i b l e competition f o r harborage sites i n r i f f l e a reas between trout and sculpins and the general disturbance of r i f f l e a reas in the f a l l by spawning salmon, trout u n d e r y e a r l i n g s and C. aleuticus may subsequently be d i s p l a c e d into pools. Cottus aleuticus were noted to be m o re abundant in flats and runs downstream of salmon spawning sites. F o o d supply, in the f o r m of salmonid f r y and eggs i s seasonal and probably does not govern the size or maintenance of sc u l p i n populations. However, d i e l d i s t r i b u t i o n of C. asper may be influenced as those caught in downstream nets between A p r i l and June contained m o s t l y salmonid fr y . Downstream movement at night of C. asper and some _C_. aleuticus during J u l y and August is a l s o suggested by trap-caught f i s h (fig. 9). E x a m i n a t i o n of day and night caught sculpins, in r i f f l e - p o o l environments, indicates predominantly nocturnal feeding. It i s suggested that C. a s p e r move out of quiet water and c o v e r (depth and/or vegetation) to feed at night. C. aleuticus ( y e a r l i n g s , adults) and C. a s p e r adults appear to occupy s i m i l a r areas during darkness and segregate into m o r e r e s t r i c t e d type habitats during daylight. The coexistence of m i x e d size groups of the two species is g r e a t e r during darkness than during daylight in both flats and pools. Daylight segregation, on the species l e v e l , may r e f l e c t the i n d i v i d u a l need f o r a c e r t a i n size g r a v e l f o r a harborage site or, as in the case of C. asper in pools, i n t r a - and i n t e r s p e c i f i c competi-tion may be o c c u r r i n g to produce in d i v i d u a l distance. Responses of f i e l d f i s h d i s p l a c e d to habitats not n o r m a l l y occupied and of l a b o r a t o r y f i s h to flow and substrate conditions strongly suggest the importance of environmental f a c t o r s in d e t e r m i n i n g d i s t r i b u t i o n and abundance and, in segregating the two species under n a t u r a l conditions. It is suggested that s c u l p i n behaviour has high adaptive value as does sc u l p i n morphology and physiology. D i f f e r e n t i a l b e h a v i o u r a l responses in C. aleuticus and C. asper strongly influence spatial and t e m p o r a l d i s t r i b u t i o n . 72 A C K N O W L E D G M E N T S I w o u l d l i k e t o a c k n o w l e d g e t h e B . C . F i s h a n d W i l d l i f e B r a n c h of t h e D e p a r t m e n t of R e c r e a t i o n a n d C o n s e r v a t i o n f o r t h e i r s u p p o r t d u r i n g t h i s s t u d y . I a m p a r t i c u l a r l y i n d e b t e d t o M r . S t u a r t B . S m i t h , p a s t C h i e f F i s h e r i e s B i o l o g i s t , f o r h i s e n c o u r a g e m e n t a n d M r . R o n T h o m a s a n d M r . E . V e r n o n f o r t h e i r s u p p o r t . T h e w r i t e r i s g r a t e f u l t o D r s . G . F . H a r t m a n a n d R . J . K r e j s a f o r t h e i r s u g g e s t i o n s a n d i n t e r e s t i n a s p e c t s of the f i e l d a n d l a b o r a t o r y s t u d i e s . T o M r . G . R . P e t e r s o n , a s p e c i a l t h a n k s f o r t h e m a n y m o n t h s o f a s s i s t a n c e i n e v e r y p h a s e of t h e f i e l d w o r k . I a l s o w i s h t o a c k n o w l e d g e M e s s r s . L . K r a u s e , A . L a n c e , J . M c L e a n a n d m e m b e r s of t h e I n s t i t u t e of F i s h e r i e s w h o w e r e i n v o l v e d i n f i e l d c o l l e c t i o n s . M i s s G . P e t r i e a n d M i s s I n e z S m i l l i e w e r e i n v o l v e d i n m a n y h o u r s of l a b o r a t o r y w o r k a n d a n a l y s e s . I a m p a r t i c u l a r l y i n d e b t e d t o m y s u p e r v i s o r , D r . J . T . M c F a d d e n , f o r h i s s t a t i s t i c a l a i d a n d g u i d a n c e t h r o u g h o u t t h e s t u d y . D r s . C . C . L i n d s e y , N . R . L i l e y a n d T . G . N o r t h c o t e o f f e r e d t h e i r a d v i c e a n d c r i t i c i s m s t h r o u g h o u t t h e s t u d y a n d t h e w r i t e r i s g r a t e f u l . T o m y w i f e , L y n n e , m y s i n c e r e g r a t i t u d e f o r h e r u n d e r s t a n d i n g , p a t i e n c e a n d h o u r s of d a t a r e c o r d i n g . 73 L I T E R A T U R E C I T E D A r m s t r o n g , J. E . 1957. S u r f i c i a l geology of New W e s t m i n s t e r map area, B r i t i s h Columbia; Geol. Surv., Canada, P a p e r 57-5, 25 pp. Bond, C. E . 1963. D i s t r i b u t i o n and ecology of f r e s h w a t e r sculpins, genus Cottus, i n Oregon. Ph.D. T h e s i s , Univ. of M i c h i g a n , 186 pp. Cole, L. C. 1962. A c l o s e d sequential test design f o r t o l e r a t i o n experiments. E c o l o g y , 43:749-753. Gee, J. H. 1961. E c o l o g y of the l e o p a r d dace (Rhinichthys falcatus) and its e c o l o g i c a l r e l a t i o n s h i p with the longnose dace (Rhinichthys cataractae) M.Sc. T h e s i s , Dept. of Zool., Univ. of B r i t i s h Columbia, 51 pp. and T. G. Northcote. 1963. Comparative ecology of two sympatric species of dace (Rhinichthys) in the F r a s e r R i v e r system, B r i t i s h Columbia. J. F i s h . Res. Bd. Canada 20 (1): 105-118. Hartman, G. F. 1965. The role of behaviour i n the ecology and i n t e r -action of u n d e r y e a r l i n g coho salmon (Oncorhynchus kisutch) and steelhead trout (Salmo g a i r d n e r i ) . J. F i s h . Res. Bd. Canada, 22 (4): 1035-1081" Hunter, J. G. 1959. S u r v i v a l and production of pink and chum salmon in a c o a s t a l stream. J i FLsh. Res. Bd. Canada, 16 (6): 835-886. K e l l e y , C. C , and R. H. Spilbury. 1939. S o i l survey of the lower F r a s e r V a l l e y . D ominion of Canada, Department of A g r i c u l t u r e . Publ. 650, T e c h n i c a l B u l l . 20, 67 pp. K r e j s a , R. J. 1965. The systematics of the p r i c k l y sculpin, Cottus  asper: A n investigation of genetic and non-genetic v a r i a t i o n within a polytypic species. Ph.D. T h e s i s , Dept. of Zool., Univ. B r i t i s h C olumbia, 109 pp. L a r k i n , P. A. 1956. I n t e r s p e c i f i c competition and population c o n t r o l in f r e s h w a t e r f i s h e s . J. F i s h . Res. Bd. Canada, 3 (3): 327-342. L i n d r o t h , A. 1955. M e r g a n s e r s as salmon and trout p r e d a t o r s in the R i v e r Indalsalven. Ibid., 36:126-132. M c A l l i s t e r , D. E . and C. C. L i n d s e y . 1959., Sy s t e m a t i c s of the freshwater sculpins (Cottus) of B r i t i s h Columbia. National Museum of Canada, B u l l . No. 172, pp. 66-89. 74 M c L a r n e y , W. O. 1964. The coastrange sculpin, Cottus aleuticus: S t r ucture of a population and predation on eggs of the pink salmon, Oncorhynchus gorbuscha. M.Sc. T h e s i s , Univ. of M i c h i g a n , 83 pp. Meehan, W. R. and W. L. Sheridan. 1966. E f f e c t s of toxaphene on fi s h e s and bottom fauna of B i g K i t o i Creek, Afognak Island, A l a s k a . U.S. Dept. of In t e r i o r R e s o u r c e s P u b l i c a t i o n 12, pp. 1-9. M i u r a , T. 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 of five i nshore species of 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 , Dept. Zool., Univ. B r i t i s h Columbia, 133 pp. Northcote, T. G. 1962. M i g r a t o r y behaviour of juvenile rainbow trout, . Salmo g a i r d n e r i , i n outlet and inlet s t r e a m s of L o o n Lake, B r i t i s h Columbia. J. F i s h . Res. Bd. Canada, 19 (2): 201-270. R i c k e r , W. E . 1958. Handbook of computations f o r b i o l o g i c a l s t a t i s t i c s of f i s h populations. J. F i s h . Res. Bd. Canada, B u l l . No. 19, 300 pp. Shappvalov, L. and A. C. Taft. 1954. The l i f e h i s t o r i e s of the steelhead rainbow trout (Salmo g a i r d n e r i g a i r d n e r i ) and s i l v e r salmon (Oncorhynchus kisutch) with s p e c i a l r e f e r e n c e to Waddell Creek, C a l i f o r n i a , and recommendations regarding t h e i r management. C a l i f , Dept. F i s h and Game, F i s h B u l l . No. 98, 375 pp. Steel, G. D. and J. H. T o r r i e . I960. P r i n c i p l e s and p r o c e d u r e s of s t a t i s t i c s . M c G r a w - H i l l Book Co. Inc., Toronto, 481 pp. Water R e s o u r c e s Branch. 1961-1964. Dept. of N o r t h e r n A f f a i r s and N a t i o n a l R e s o u r c e s . Surface Water Supply of Canada, P a c i f i c Drainage, Water R e s o u r c e s P a p e r Nos. 136, 139, 142 and 146. A P P E N D I X T A B L E I. Summary of monthly total d i s s o l v e d solids (TDS) r e c o r d e d at six s e l e c t e d stations, L i t t l e C ampbell R i v e r , White Rock, B.C. Stations 1 and 2 under sa l i n i t y effects. 1965 1965 1966 1966 R i v e r a r e a Station Aug Sept Oct Nov Dec Jan F e b M a r A p r June L O W E R 7 131 143 165 115 69 50 66 73 80 124 :*5 122 156 122 145 93 61 123 120 118 135 2* 140 - - - 570 830 410 730 1100 -M I D D L E 10 116 99 101 77 -5\0 40 60 62 63 113 U P P E R 14 118 147 142 82 51 50 63 60 56 82 13 149 81 87 75 51 44 49 52 49 80 * under s a l i n i t y influence A P P E N D I X T A B L E II. Summary of pH r e c o r d e d at 14 c o l l e c t i n g stations, L i t t l e C a m p b e ll R i v e r , White Rock, B.C. 1965 1965 1966 1966 R i v e r a r e a Station July Aug Sept Oct Dec Jan F e b A p r M a y June L O W E R 8 7.2 7.3 8.4 7.8 8.3 8.1 7 7.4 7.2 8.0 7.6 8.3 8.7 8.1 7.6 7.6 6a 7.9 7.5 8.0 7.6 8.3 8.0 5 7.9 7.5 7.8 7.6 8.4 8.7 8.0 7.5 7.7 3 8.1 8.3 8.4 7.9 8.6 8.0 2 7.3 8.3 8.2 7.8 8.3 8.3 7.8 7.2 7.3 M I D D L E 12 D R Y DRY DRY D R Y 7.8 8.3 D R Y DRY 11 7.3 7.4 7.7 7.4 7.8 8.3 10 7.5 7.4 7.7 7.8 8.1 8.9 8.3 7.6 7.6 9 8.0 7.7 8.3 7.8 8.3 8.3 U P P E R 17 8.0 8.0 7.9 7.6 8.3 8.2 16 7.5 7.9 7.9 7.7 8.3 8.7 14 7.8 7.7 8.1 7.7 8.1 8.9 8.7 7.6 7.8 13 7.8 7.7 8.1 7.6 8.3 8.9 8.7 7.7 7.8 A P P E N D I X T A B L E III. Summary of monthly temperature r e c o r d e d at 14 c o l l e c t i n g stations, M a y 18, 1965, to June 16, 1965, L i t t l e C a m p b e l l R i v e r , White Rock, B.C. R i v e r a r e a Station 1965 18 M a y . 15 . 'June 1 Jul y 3 Aug 5 Sept 13 Oct 8 Nov 1965 10 Dec 1966 15 Jan 17 Feb 6 A p r 15 M a y 1966 16 June L O W E R 8 11.0 14.0 19. ,0 18. .0 13. 0 11. 0 8 .0 6, .5 4.5 6.0 13.0 7 11.0 14.0 19. 5 18. .0 13. .0 11. 0 9, .5 6, .5 4.5 6.0 13.0 6a 11.0 14.0 19. .5 18. .0 13. .0 11. 0 9 .5 7, .0 5.0 6.0 13.0 5 12.0 14.0 20. .0 19. .0 13. .0 11. .0 9 .5 7, .0 5.5 6.0 11.5 3 14.0 15.0 26. .5 24. ,5 16. ,5 11. 0 9 .0 6. .0 4.5 5.5 13.0 2 15.0 15.5 24. .5 24. 0 15. ,5 11. .5 9 .5 5, .5 4.5 5.5 14.0 M I D D L E 12 13.0 17.0 D RY DRY D R Y DRY 9 .0 6, ,5 4.0 4.5 14.0 DRY D R Y : i l 10.5 15.0 16. 0 13. 0 12. ,0 1.0. .5 8, .0 6. .5 4.0 4.5 13.0 14.5 10 10.0 14.0 15. ,5 14. 5 12. ,5 10. 0 8. .0 6, ,5 4.0 5.0 13.0 15.0 9 1(0.5 13.0 . 17. 0 18. 0 13. .0 11. 0 8 .0 6. .5 4.5 5.0 13.0 U P P E R 17 13.5 18.0 19. .5 18. 0 15. .0 9. 5 9, ,0 6, ,0 4.0 4.5 14.0 16 14.5 19.0 21. 0 21. .0 17. .5 10. 0 9, .0 16, .0 4.0 4.5 14.0 14 15.0 19.0 24. 0 23. 0 19. 0 12. 0 9, .0 5. ,5 4.0 4.5 14.0 20.0 13 15.0 18.0 25. .5 23. 0 19. ,5 12. 0 9, .0 6. ,0 4.0 4.5 14.0 21.5 A P P E N D I X T A B L E IV. Summary of some p h y s i c a l conditions in Sections A, 3 and G, L i t t l e C a m p b e l l R i v e r , White Rock, B.C. Substrate g r e a t e r than 1.25 cm c o n s i d e r e d coarse; a l l others c o n s i d e r e d fine. Habitats c l a s s i f i e d as c u r r e n t areas if v e l o c i t y greater than 23 cm/sec, or as non-current areas if l e s s . T I O N A S E C T I O N B S E C T I O N C A r e a Approx. A r e a Approx. A r e a Approx. (sq.m. ,) % (sq.m.) % (sq.m.) % T o t a l a r e a 763 1057 348 T o t a l c o a r s e substrate 654 86 974 93 286 82 T o t a l fine substrate 109 14 83 7 62 18 T o t a l c u r r e n t a r e a 499 65 833 79 256 74 T o t a l n o n-current a r e a 264 35 224 21 92 26 T o t a l c o a r s e - c u r r e n t a r e a 466 61 795 75 245 71 T o t a l c o a r s e - n . c. a r e a 188 25 179 17 54 15 T o t a l f i n e - c u r r e n t a r e a 22 3 32 3 24 1 T o t a l fine-n. c. a r e a 73 9 45 4 24 7 Other 14 •> 6 1 21 6 A P P E N D I X T A B L E V Number and d i s t r i b u t i o n of mean depths and v e l o c i t i e s of 13Z c o l l e c t i o n sites in Section A, B and C, August 16, 1965. Mean values a s s e m b l e d in groups of 7.6 cm/sec and 7.6 cm fo r c u r r e n t and depth r e s p e c t i v e l y . L i m i t s of r i f f l e , run, flat and pool'indicated by dividing l i n e s . D E P T H (CM) 0.00- 7.62- 15 .24- 22.86- 30.48- 38.10- 45.72- 53.34-7.31 14.93 22.55 30/17 37.79 45.41 53.03 60.65+ 0.00- 7.31 - 3 - 3 - - 3 3 - 3 5 - 1 - - 4 1 - 6 7 2 7.62-14.93 ( F L A T S ) 1 4 - - 1 2 2 4 2 - 1 - - 2 - 2 - - 6 15.24-22.55 1 1 - 3 3 4 1 2 - 1 1 2 - - - - - 1 (POOLS) 22.86-30.17 _. _ 2 •1 12 1 1 - 1 30.48-37.79 1 - - 2 3 1 38.10-45.41 ( R I F F L E S ) - - - 1 1 2 - - 2 45.72-53.03 - 1 - 1 - - - - 1 (RUNS) 53.34-60.55 1 - - - - 1 - - 2 60.96-68.27 1 - - - - 2 68.58-75.89 -. - 1 -76.20-83.82 83.82-91.13 - - 1 Section A B C A B C A B C A B C A B C A B C A B C A B C u w 10 O Q W W co H W & D U A P P E N D I X T A B L E VI Summary of multiple c o r r e l a t i o n c o e f f i c i e n t s (R) fo r the same analyses on pa r t i t i o n e d data (different capture method) of section seining. D e s c r i p t i o n of analys es given on pag ;e 35. Species and Size C l a s s . (dependent v a r i a b l e s ) C o r r e l a t i o n C o e f f i c i e n t s (R) T o t a l A n a l y s i s 1 0.402 C. as p e r 2 -3 -4 0.730 5 0.744 6 0.782 Adu l t A n a l y s i s 1 0.387 C. as p e r 2 -3 -4 0.734 5 0.748 6 0.782 T o t a l A n a l y s i s 1 0.503 C. aleuticus 2 0.451 3 0.635 4 0.659 5 0.772 6 0.827 Y e a r l i n g A n a l y s i s 1 0.461 C. aleuticus ' 2 0.441 3 0.582 4. 0.657 5 0.759 6 0.814 Adult A n a l y s i s 1 0.418 C. aleuticus 2 0.372 3 0.542 4 0.504 5 0.562 6 0.775 C. asper to A n a l y s i s 1 0.396 C. aleuticus 2 0.383 R A T I O 3 0.450 4 0.402 5 0.483 6 0.527 A P P E N D I X T A B L E VII Summary of c u r r e n t and non-current p r e f e r e n c e s of C. aleuticus and C. a s p e r ( L a b o r a t o r y Fish. A). Sequential test design a n a l y s i s (Cole, 1962)* employed f o r single-tested f i s h ; group f i s h showing ove r 70 p e r cent o c c u r r e n c e f o r an experimental condition c o n s i d e r e d ! selective; Single / No H o u r s of Specie s Size (mm) group C u r r e n t N o n-curr. Choice Observations R e s u l t s * C. aleuticus 70-95 S 10 2 C u r r e n t 85-90 S 11 4 - C u r r e n t 110 + S 6 - - C u r r e n t 35-40 G 19 17 9 3 No p r e f e r e n c e 60-65 G 44 7 9 4 C u r r e n t C. a s p e r 20-25 S 7 6 4 No p r e f e r e n c e 20-25 S 1 6 6 1 No p r e f e r e n c e 20-35 S 5 8 5 - No p r e f e r e n c e 30-35 S 7 6 4 No p r e f e r e n c e 40-45 S 11 25 4 No p r e f e r e n c e 70-75 S 2 10 - N o n - c u r r e n t 70-95 S 7 6 2 No p r e f e r e n c e 85-90 S 6 6 2 No p r e f e r e n c e 85-90 S 8 7 - No p r e f e r e n c e 95-110 s 6 7 2 No p r e f e r e n c e 40-45 G 21 57 27 7 No p r e f e r e n c e 70-75 G 13 47 1 5 Non - c u r r e n t 95-100 G 12 31 2 3 No p r e f e r e n c e 110 + G 5 36 4 3 Non - c u r r e n t 82 A P P E N D I X T A B L E VIII Summary of responses to c u r r e n t and non-current by f i s h h eld over a r t i f i c i a l habitats f o r 60 days. ( L a b o r a t o r y F i s h C). Random Holding conditions F l o w response T e s t i n g Size O r d e r Species Substrate F l o w (mm) Replicate Initial Interim F i n a l 7. A l Co c 60 2 ns non-c non-c 40. A l F i c 60 5 ns ns c 51. A l F i non-c 60 1 non-c non-c c 49. A l F i non-c 35 4 c c c 58. A l F i non-c 85 2 non-c non-c ns 8. A l Co c 60 3 c c c 25. A l Co non-c 60 5 c c c 111. A s F i non-c 60 1 non-c non-c non-c 59. A l F i non-c 85 1 ns c c 75. A s Co c 85 5 ns ns c 104. A s F i c 85 4 non-c non-c non-c 67. A s Co c 60 2 non-c ns non-c 6. A l Co c 60 1 c non-c non-c 71. A s Co c 85 2 non-c non-c c 52. A l F i non-c 65 2 non-c c c 12. A l Co c 85 3 ns ns non-c 26. A L Cer . non-c 85 1 c c c 60. A l F i non-c 85 5 c non-c non-c 119. A s F i non-c 85 5 non-c non-c non-c 110. A s F i non-c 35 5 non-c non-c non-c 66. A s Co c 60 2 no f i s h 93. A s F i c 35 3 no f i s h 77. A s Co non-c 35 2 ns non-c non-c 64. A s Co c 35 4 no f i s h 94. A s F i c 35 4 no f i s h 41. A l F i c 85 1 non-c non-c non-c 83. A s Co non-c 60 3 no f i s h 20. A l Co non-c 35 5 non-c non-c non-c 53. A l F i non-c 60 3 non-c non-c non-c 16. A l Co non-c 35 1 non-c c c 55. A l F i non-c 60 5 ns c c 101. A s F i c 85 1 c c c 100. A s F i c 60 5 non-c non-c non-c •"27. A l Co non-c 85 2 ns non-c non-c 76. A s Co non-c 35 1 non-c non-c non-c 46. A l F i non-c 35 1 non-c c c 39. A l F i c 60 4 . ns ns c 78. A s Co non-c 35 3 non-c non-c non-c 80. A s Co non-c 35 5 non-c c c 47. A l F i non-c 35 2 non-c non-c non-c 83 A P P E N D I X T A B L E VIII (continued) Random Holding conditions F l o w response T e s t i n g Size O r d e r Species Substrate F l o w (mm.) Replicate Initial Interim F i n a l 50. A l F i non-c 35 5 c c c 31. A l F i c 35 1 c c c 79. A s Co non-c 35 4 non-c non-c non-c 115. A s F i non-c 60 5 non-c ns c 44. A l F i c 85 4 c c c 36. A l F i c 60 1 ns c c 103. • A s F i c 85 3 c c c 73. A s F i c 85 3 non-c non-c non-c 14. A l Co c 85 4 c c c .:. 58. A l F i non-c 85 3 c c c 70. A s Co c 60 5 ns ns non-c 1.05. A s F i c 85 5 non-c non-c non-c 81. . A s Co non-c 60 1 non-c non-c non-c 37. A l F i c 60 2 non-c non-c c 1. A l Co c 35 1 ns non-c non-c 48. A l F i non-c 35 3 c c C 12. A l Co c 85 2 ns c C 33. A l Co c 35 3 c c c 92. A s F i c 35 2 no f i s h 32. A l F i c 35 2 c c c *38. A l F i c 60 3 c c c lis; A s F i non-c 85 3 c c c 18. A l Co non-c 35 3 non-c ns non-c 97. A s F i c 60 2 c non-c non-c 19. A l Co non-c 35 4 c c c 95. A s F i c 35 5 no f i s h A l F i non-c 85 1 non-c non-c non-c 89. A s Co non-c 85 4 ns non-c non-c 113. A s F i non-c 60 3 non-c non-c non-c 3. A l Co c 35 3 non-c non-c nbn-c 120 A s F i non-c 85 5 non-c non-c c 71 A s Co c 85 1 non-c non-c non - c 87. A s Co non-c 85 2 non-c non-c non-c 10. A l Co c 60 5 c c c 43. A l F i c 85 3 non-c ns c 114. A s F i non-c 60 4 non-c non-c non-c 90. A s Co non-c 85 5 non-c non-c non-c 54. A l F i non-c 60 4 non-c non-c c 17. A l Co non-c 35 2 ns c c 74. A s Co c 85 4 non-c ns ns 63. A s Co c 35 3 no f i s h 84 A P P E N D I X T A B L E VIII (continued) Random Holding conditions F l o w response T e s t i n g S i z e O r d e r Species Substrate F l o w (mm) Replicate Initial Interim F i n a l 24. A l Co non-c 60 4 ns c c 28. A l Co non-c 85 3 non-c c c 105. A s F i non-c 35 1 no f i s h 35. A l F i c 35 5 ns c c 21. A l Co non-c 60 1 ns ns non-c 15. A l Co c 85 5 ns ns c 34. A l F i c 35 4 c c c 109. A s F i non-c 35 4 no f i s h 99. A s F i c 60 4 non-c non-c non-c 117. As F i non-c 85 2 non-c non-c non-c 4. A l Co c 35 4 c c non-c 107. A s F i non-c 35 2 no f i s h 30. A l Co non-c 85 5 ns c c 85. A s Co non-c 60 5 non-c ns ns 45. A l F i c 85 5 c c c 11. A l Co c 85 1 ns ns non-c 88. A s Co non-c 85 3 ns non-c non-c 102. A s Co c 85 2 non-c c c 22. A l Co non-c 60 2 non-c c c 91. A s F i c 35 1 no f i s h 42. A l F i c 85 2 c non-c non-c 29. A l Co non-c 85 4 non-c non-c non-c 84. A s Co non-c 60 4 c c c 108. A s F i non-c 35 3 no f i s h 68. A s Co c 60 3 c c c 82. A s Co non-c 60 2 non-c non-c non-c 98. A s F i c 60 3 non-c non-c non-c 86. As Co non-c • 85 1 ns non-c non-c 112. A s F i non-c 60 2 ns ns non-c 9. A l Co c 60 4 ns ns c 66. A s Co c 60 1 non-c c c 5. A l Co c 35 5 non-c c c 96. A s F i c 60 1 non-c non-c ns 116. A s F i non-c 85 1 non-c c c 61. As F i c 35 i no f i s h 2. A l Co c 35 2 ns non-c non-c 23. A l Co non-c 60 3 non-c c c 65. A s Co c 35 5 no f i s h 61. A s Co c 35 1 no f i s h L E G E N D A l C u r r e n t p r e f e r e n c e A s C. as p e r N o n - c u r r e n t p r e f e r e n c e Co No select i o n of either F i F i n e substrate flow condition 

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