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Comparative feeding habits of the fur seal (Callorhinus ursinus), sea lion (Eumetopias jubata) and harbour… Spalding, David Joseph Reede 1963

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COMPARATIVE FEEDING HABITS OF THE FUR SEAL (CALLORHINUS URSIMJS), SEA LION (EUMETOPIAS JUBATA) AND HARBOUR SEAL (PHOCA VITULINA) ON THE BRITISH COLUMBIA COAST by DAVID JOSEPH SPALDING B. A., 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 , 19£6 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS i n t h e D e p a r t m e n t o f ZOOLOGY We a c c e p t t h i s t h e s i s as 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 THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1963. I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y of ' B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r -m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s , . I t i s understood t h a t copying, or p u b l i -c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department of < ; 7 ^ ^ ^ C 5 ^ ' ^ The U n i v e r s i t y of. B r i t i s h Columbia,. Vancouver 8, Canada. Date ^hfa* / ^ 3 - i i -ABSTRACT F e e d i n g h a b i t s o f f u r s e a l s ( C a l l h o r i n u s u r s i n u s ) , sea l i o n s ( E u m e t o p i a s j u b a t a ) and h a r b o u r s e a l s (Phoca v i t u l i n a ) have been examined a l o n g t h e B r i t i s h C o l u m b i a coast.- C o l l e c -t i o n s were made ou t t o 35 m i l e s f r o m s h o r e . A l l p e r t i n e n t p u b l i s h e d and u n p u b l i s h e d d a t a have b e e n combined w i t h t h e o b j e c t o f a s s e s s i n g t h e e f f e c t o f p i n n i p e d p r e d a t i o n u pon com-m e r c i a l l y v a l u a b l e f i s h s t o c k s . A t o t a l o f 126 h a r b o u r s e a l s t o machs, 2,113 f u r s e a l stomachs and 393 s e a l i o n stomachs were a v a i l a b l e . C o m p a r a t i v e anatomy o f t h e d i g e s t i v e t r a c t was examined and n o t a b l e d i f f e r e n c e s were f o u n d i n t h e r e l a -t i v e l y l o n g e r d i g e s t i v e t r a c t and l a t e e r u p t i o n o f permanent t e e t h i n t h e sea l i o n . P u b l i s h e d d a t a i n d i c a t e t h a t f u r s e a l s , s e a l i o n s , and h a r b o u r s e a l s e a t an amount o f f o o d e q u a l t o 6$ o f t h e i r body w e i g h t p e r day w i t h a r a n g e o f 2$ t o 11$. A l l s a mples were g r o u p e d as t o s e a s o n and a r e a o f c o l l e c t i o n and c o m p a r a t i v e s e a s o n a l f e e d i n g h a b i t s were d i s c u s s e d . The e f f e c t o f t h e r e p r o d u c t i v e p e r i o d upon f e e d i n g h a b i t s was e x a m i n e d : t h e r e i s l i t t l e e v i d e n c e r e g a r d i n g f u r s e a l f e e d i n g h a b i t s on t h e r o o k e r i e s e x c e p t f o r c o n f l i c t i n g o b s e r v a t i o n s made on harem b u l l s ; t h e m a j o r i t y o f t h e s e a l i o n r o o k e r y p o p -u l a t i o n f a s t s f o r a f e w days o n l y , d u r i n g p u p p i n g ; h a r b o u r s e a l s on t h e Skeena R i v e r a p p e a r t o f a s t f o r a t l e a s t p a r t o f J u n e . T h e r e i s no e v i d e n c e o f i n t e r s p e c i f i c c o m p e t i t i o n b e t w e e n t h e t h r e e s p e c i e s s t u d i e d on t h e B r i t i s h C o l u m b i a c o a s t . Sea l i o n s and h a r b o u r s e a l s e a c h y e a r e a t an e s t i m a t e d amount e q u i v a l e n t t o 1.6$ o f t h e a n n u a l c o m m e r c i a l s a l m o n c a t c h and 2.7% o f t h e a n n u a l c o m m e r c i a l h e r r i n g c a t c h . P r e d a t i o n a t t h i s l e v e l i s b e l i e v e d t o be o f n e g l i g i b l e i m p o r t a n c e i n t h e r e d u c -t i o n o f e x i s t i n g salmon and h e r r i n g s t o c k s . I n s u f f i c i e n t d a t a f r o m w a t e r s g r e a t e r t h a n 35 m i l e s f r o m s h o r e p r e c l u d e s an a s s e s s m e n t o f f u r s e a l p r e d a t i o n upon o c e a n s a l m o n . F u r t h e r o f f s h o r e c o l l e c t i o n s s h o u l d be made. - x i i -ACKNOWLEDGEMENTS The a s s i s t a n c e and encouragement of D r . I . MoT. Cowan, Head, D e p a r t m e n t o f Z o o l o g y , The 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 , o v e r t h e s e v e r a l y e a r s n e c e s s a r y t o c o m p l e t e t h i s t h e s i s i s g r a t e f u l l y a c k n o w l e d g e d . D r . A. W. H. N e e d i e r , D i r e c t o r o f t h e F i s h e r i e s R e s e a r c h B o a r d ' s S t a t i o n i n Nanaimo, has made a v a i l a b l e a l l d a t a n e c e s s a r y f o r t h i s s t u d y ; I w i s h t o e x t e n d my t h a n k s t o him and t h e F i s h e r i e s R e s e a r c h B o a r d o f Canada f o r t h e i r c o o p e r a t i o n . The f o l l o w i n g have r e a d t h i s t h e s i s i n d r a f t f o r m and made many h e l p f u l s u g g e s t i o n s : D r . W. S. Hoar, D r . N. J . W i l i m o v s k y , D r . J . B e n d e l l and D r . D. C h i t t y o f 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 ; Mr. F . C. W i t h l e r , Mr. G. C. P i k e , and Mr. R. L e B r a s s e u r of t h e B i o l o g i c a l S t a t i o n i n Nanaimo. The a s s i s t a n c e o f D r . M. P. S h e p a r d and D r . F. H. C. T a y l o r i n a s s e s s i n g t h e e f f e c t o f p i n n i p e d p r e d a t i o n upon salmon and h e r r i n g s t o c k s i s g r a t e f u l l y a c k n o w l e d g e d . The c o l l e c t i n g o f s e a l s and s e a l i o n s i s d i f f i c u l t , o f t e n u n p l e a s a n t and o c c a s i o n a l l y d a n g e r o u s . The c o o p e r a t i o n o f t h o s e m e n t i o n e d b e l o w has i n c r e a s e d t h e number o f s p e c i m e n s a v a i l a b l e f o r t h i s s t u d y : Mr. R. K e l l y and crew o f t h e " P a c i f i c Ocean"; M e s s r s . T. and A. B o r o e v i c h and crew o f t h e " S t . J o s e p h " ; Mr. D. B e r v e n and crew of t h e "T. W. I s l a n d e r " ; Mr. W. S e c o r d and Mr. D. S e c o r d ; M e s s r s . D. and W. McNaughton o f Pender H a r b o u r ; Mr. I . B. M a c A s k i e , Mr. T. B i n n e r s l e y , Mr. W. P i n c k a r d and Mr. F. V e l s e n o f t h e B i o l o g i c a l S t a t i o n . The D e p a r t m e n t o f F i s h -e r i e s has c o o p e r a t e d i n t h e c o l l e c t i o n o f s p e c i m e n s whenever - x i i i -p o s s i b l e . I a l s o w i s h t o extend my thanks t o Mr. C. M o r l e y f o r h i s e x c e l l e n t p h o t o g r a p h s , and t o Mr. MacAskie f o r h i s s k u l l d r a w i n g s . - i v -TABLE ' OP C ONTENTS Page A b s t r a c t i i L i s t of F i g u r e s v i i i L i s t o f T a b l e s x Acknowledgements x i i INTRODUCTION 1 HISTORY OF PINNIPED FOOD HABIT STUDIES 1 A. F e e d i n g h a b i t s o f s e a l s o u t s i d e B r i t i s h C o l u m b i a ' s c o a s t a l w a t e r s 2 B. F e e d i n g h a b i t s o f s e a l s i n B r i t i s h C o l u m b i a w a t e r s 6 1. F u r s e a l s .' 6 2. Sea l i o n s . 7 3. H a r b o u r s e a l s 7 METHODS AND MATERIALS 8 A. S p e c i m e n c o l l e c t i o n 8 1. F u r s e a l s 8 2. Sea l i o n s 9 3. H a r b o u r s e a l s .. 13 B. A n a l y s i s of s t o m a c h c o n t e n t s ll). 1. D e g r e e o f f u l l n e s s 15 2. Numbers o f i n d i v i d u a l s 15 3. Dominant i t e m s 15 if . P o i n t s 15 5. Volume and w e i g h t s 15 6. Number o f o c c u r r e n c e s l6 C. I d e n t i f i c a t i o n o f s t o m a c h c o n t e n t s 22 DISTRIBUTION, NUMBERS AND MIGRATORY BEHAVIOUR 23 - v -Page A. G e n e r a l h a b i t a t d e s c r i p t i o n 23 1. F u r s e a l s 2k 2. Sea l i o n s 25 3. H a r b o u r s e a l s 26 COMPARATIVE ANATOMY 28 A. D e n t i t i o n . 28 1. Sea l i o n s •. 28 2. F u r s e a l s 31 3. H a r b o u r s e a l s 31 B. D i g e s t i v e t r a c t 32 FEEDING HABITS 35 A. C o m p a r a t i v e f e e d i n g b e h a v i o u r 35 1. C a p t u r e of p r e y 35 (a) F u r s e a l s 35 (b) Sea l i o n s 36 ( c ) H a r b o u r s e a l s 36 2. F e e d i n g i n r e l a t i o n t o h o u r s a f t e r s u n r i s e ... 37 B. D a i l y f o o d c o n s u m p t i o n 38 C. C o m p a r i s o n o f f o o d i t e m s e a t e n 38 D. U n u s u a l stomach c o n t e n t s 1+6 E . C o m p a r a t i v e s e a s o n a l f e e d i n g h a b i t s l+Q 1. W i n t e r - s p r i n g 52 (a) J a n u a r y 52 (b) F e b r u a r y 52 ( c ) M a r c h 53 (d) A p r i l 53 (e) May Sk - v i -Page 2. Summer 55 (a) F u r s e a l s 55 (b) Sea l i o n s 5£ ( c ) H a r b o u r s e a l s 56 3. F a l l 56 (a) Sea l i o n s 56 (b) H a r b o u r s e a l s 57 F. P r e d a t o r - p r e y s i z e r e l a t i o n s h i p s 58 1. I n t e r s p e c i f i c d i f f e r e n c e s 58 2. I n t r a s p e c i f i c d i f f e r e n c e s ( f u r s e a l s ) 59 G. F e e d i n g h a b i t s and r e p r o d u c t i o n 63 1. F u r s e a l s 63 2. Sea l i o n s 61+ 3. H a r b o u r s e a l s 67 I}.. F a s t i n g 68 H. I n t e r s p e c i f i c c o m p e t i t i o n 70 EFF E C T OF SEAL AND SEA LION PREDATION UPON BRITISH COLUMBIA'S COMMERCIAL FISHERY TU-A. F u r s e a l s 75 1. H e r r i n g 75 2. Salmon , 76 3. T r a w l f i s h e r y 78 B. Sea l i o n s : 80 1. H e r r i n g 80 2. Salmon 8 l 3. H a l i b u t ' 85 1^ . A v a i l a b i l i t y o f f i s h a r o u n d , sea l i o n r o c k s ... 85 - v i i -Page C. H a r b o u r s e a l s 87 1. H e r r i n g 87 2. Sal m o n 87 CONCLUSIONS 89 A. E f f e c t o f f u r s e a l s , s ea l i o n s and h a r b o u r s e a l s upon c o m m e r c i a l l y v a l u a b l e f i s h 89 LITERATURE CITED . .. . 93 APPENDIX 1 100 - v i i i -L I S T OP FIGURES Page F i g u r e 1. M. V. " P a c i f i c Ocean", u s e d e x t e n s i v e l y f o r c o l l e c t i n g f u r s e a l s , h a r b o u r s e a l s and s e a l i o n s 10 F i g u r e 2. C o l l e c t i n g sea l i o n s , S c o t t I s l a n d s , 1959'••• H F i g u r e 3. A n a l y s i s o f s t omach c o n t e n t s . Top: examples f r o m s k e l e t o n c o l l e c t i o n B o t t o m : w e i g h i n g f u r s e a l stomach c o n t e n t s . . 12 F i g u r e ij.. C o m p a r i s o n between a p e r c e n t b y o c c u r r e n c e a n a l y s i s and a p e r c e n t by volume a n a l y s i s o f c o n t e n t s f r o m 869 f u r s e a l stomachs (1958-1961 d a t a ) 18 F i g u r e 5» S m a l l b l a c k cod f o u n d i n f u r s e a l s t o m a c h . . . . 19 F i g u r e 6. T o p : 3-1+-month-old f e m a l e s e a l i o n s k u l l B o t t o m : 15-month-old f e m a l e sea l i o n s k u l l (b - d e c i d u o u s t e e t h ) 29 F i g u r e 7. Top: Lower jaw f r o m 9-month-old f e m a l e s e a l i o n , s h o w i n g permanent c a n i n e s C e n t e r : Young f e m a l e h a r b o u r s e a l s k u l l B o t t o m : 9-month-old f e m a l e f u r s e a l s k u l l . . . 30 F i g u r e 8. F u r s e a l s t o m a c h v o l u m e s and h o u r s a f t e r s u n r i s e LpO F i g u r e 9« P e r c e n t empty stomachs and h o u r s a f t e r s u n r i s e ( f u r s e a l s ) 1+1 F i g u r e 10. Mean.stomach" volume o f 269 s e a l i o n s , and h o u r s a f t e r s u n r i s e 1+2 F i g u r e IL P e r c e n t empty stomachs and h o u r s a f t e r s u n r i s e i n a sample o f 269 s e a l i o n s t o m a c h s . 1+3 F i g u r e 12. Mean s t o m a c h volumes and h o u r s a f t e r s u n r i s e i n a sample o f 50 h a r b o u r s e a l s 1+1+ F i g u r e 13. Stomach c o n t e n t s o f f u r s e a l s , sea l i o n s , h a r b o u r s e a l s , c o l l e c t e d a l o n g t h e c o a s t o f B r i t i s h C o l u m b i a 1+5 F i g u r e l l ] . . C o l l e c t i n g a r e a s on t h e B r i t i s h C o l u m b i a c o a s t ( A r e a IV i n c l u d e s a l l p r o t e c t e d i n l e t s and c h a n n e l s ) 1+9 F i g u r e 15. A n a l y s i s o f 699 f u r s e a l stomachs c o n t a i n i n g f o o d , s h o w i n g s e l e c t i v e f o o d p r e f e r e n c e s a c c o r d i n g t o age 60 - i x -Page F i g u r e 16. T r i a n g l e I s l a n d . Top: Harbour s e a l h a b i t a t b e h i n d b r e a k e r s . Sea l i o n r o c k i n f a r r i g h t background Bottom: Sea l i o n r o c k w i t h T r i a n g l e I s l a n d i n background 1 73 F i g u r e 17. Per cent f r e q u e n c y of o c c u r r e n c e of h e r r i n g i n f u r s e a l stomachs o f f s o u t h e r n Vancouver I s l a n d and m i l e s of h e r r i n g spawn i n B a r k l e y and C l a y o q u o t Sounds (139 stomachs) 77 F i g u r e 18. T r a w l f i s h e r y c a t c h s t a t i s t i c s f o r 1959-I96l (White Rocks f i s h i n g g r o u n d s ) , and f u r s e a l stomach c o n t e n t s c o l l e c t e d f r om t h i s v i c i n i t y 79 F i g u r e 19. Salmon c a t c h e s ( a l l s p e c i e s ) and the d e c r e a s i n g sea l i o n p o p u l a t i o n i n f i s h -e r i e s area 12, from 19Bk t o 1961 8I4. - X -L I S T OP TABLES Page T a b l e I . M o n t h l y c o l l e c t i o n d a t e s f o r a l l a v a i l -a b l e h a r b o u r . s e a l , f u r s e a l and sea l i o n s tomachs Ik T a b l e I I . C o a s t a l h a b i t a t s and p i n n i p e d d i s t r i b u t i o n . 2 l | T a b l e I I I . R a t i o o f whole i n t e s t i n e l e n g t h t o body l e n g t h of f u r s e a l s , sea l i o n s and h a r b o u r s e a l s . Mean l e n g t h s and r a t i o s o f means a r e shown a t t h e b o t t o m o f e a c h r e s p e c t i v e c o l u m n . D a t a f r o m a n i m a l s g r e a t e r t h a n one y e a r o f age 33 T a b l e I V . Maximum numbers o f c e r t a i n f o o d i t e m s f o u n d i n i n d i v i d u a l s tomachs of f u r s e a l s , sea l i o n s and h a r b o u r s e a l s 3& T a b l e V . D a i l y f o o d c o n s u m p t i o n o f p i n n i p e d s as r e p o r t e d i n t h e l i t e r a t u r e , p l u s t h e max-imum w e i g h t s o f s tomach c o n t e n t s f r o m i n d i v i d u a l a n i m a l s c o l l e c t e d i n t h e f i e l d . . 39 T a b l e V I . P u r s e a l s t o m a c h c o n t e n t s by month and a r e a . S o u r c e o f d a t a as i n T a b l e 1 50 T a b l e V I I . H a r b o u r s e a l and sea l i o n s t o m a c h c o n t e n t s b y month and a r e a . S o u r c e o f d a t a as i n T a b l e I 51 T a b l e VLTT. C o m p a r i s o n o f l a r g e and s m a l l f o o d i t e m s e a t e n by f u r s e a l s and sea l i o n s . F r e -quency e x p r e s s e d as a p e r c e n t a g e o f t o t a l o c c u r r e n c e s of a l l f o o d i t e m s f r o m T a b l e v i 6 i T a b l e I X . A n a l y s i s o f 699 f u r s e a l s tomachs c o n -t a i n i n g f o o d s h o w i n g s e l e c t i v e f e e d i n g b e h a v i o u r a c c o r d i n g t o a g e . ( D a t a f r o m p r e s e n t i n v e s t i g a t i o n o n l y . ) 62 T a b l e X . C h a n g i n g r a t i o o f s tomachs w i t h f o o d t o empty stomachs t h r o u g h o u t t h e p u p p i n g and b r e e d i n g s e a s o n i n 228 male and f e m a l e sea l i o n s t o m a c h s . Pups n o t i n c l u d e d . ( D a t a f r o m p r e s e n t i n v e s t i g a t i o n o n l y . ) 65 T a b l e X I . C o n t e n t s o f 23 sea l i o n stomachs f r o m • B a r k l e y S o u n d : 1I4. c o l l e c t e d i n December , 1915 (Newcombe e_t a l . , 1918); n i n e c o l -l e c t e d d u r i n g t h e p r e s e n t i n v e s t i g a t i o n . . . 8 l T a b l e X I I . C o n t e n t s f r o m 52 sea l i o n stomachs f r o m t h e S c o t t I s l a n d s and a d j a c e n t w a t e r s . ( D a t a f r o m p r e s e n t i n v e s t i g a t i o n o n l y . ) . . . 83 - x i -Page Appendix Table I . S c i e n t i f i c and common names of food items mentioned i n t e x t 101+ Appendix Table I I . Pinniped stomach contents from c o l l e c t i o n s made i n North American waters and the Western P a c i f i c ... 110 INTRODUCTION The p r e d a t o r y a c t i v i t i e s o f s e v e r a l members o f t h e o r d e r P I n n i p e d i a p r o v o k e h e a t e d arguments whenever i n s h o r e f i s h e r i e s a r e c a r r i e d out n e a r s e a l o r sea l i o n p o p u l a t i o n s . On t h e one hand c o m m e r c i a l f i s h e r m e n a d v o c a t e s t r i n g e n t c o n t r o l s , and i n some i n s t a n c e s c o m p l e t e e r a d i c a t i o n , o f a l l p i n n i p e d s whose d e p r e d a t i o n s may a f f e c t f i s h c a t c h e s . "The o n l y good s e a l ( o r s e a l i o n ) i s a.^deadrone" i s a f a v o u r i t e e x p r e s s i o n . On t h e o t h e r hand many n a t u r a l i s t s and s e a l l o v e r s v i g o r o u s l y oppose s u c h c o n t r o l m e a s u r e s . C o n t r o l i s o f t e n synonomous w i t h " s l a u g h t e r " and " e x t i n c t i o n " t o some members o f t h e l a t t e r g r o u p . T h r e e p i n n i p e d s , t h e n o r t h e r n f u r s e a l ( C a l l o r h i n u s  u r s i n u s ) , t h e n o r t h e r n s e a l i o n ( E u m e t o p i a s j u b a t a ) , and t h e h a r b o u r s e a l (Phoca v i t u l i n a ) , a r e f o u n d i n B r i t i s h C o l u m b i a ' s c o a s t a l w a t e r s where c o m m e r c i a l f i s h i n g i s c a r r i e d o u t . T h i s s t u d y i s an a t t e m p t t o d e s c r i b e t h e s e a s o n a l f e e d i n g h a b i t s o f t h e s e t h r e e p i n n i p e d s w i t h p a r t i c u l a r r e f e r e n c e t o t h e c o m m e r c i a l l y v a l u a b l e f i s h s p e c i e s i n t h e i r d i e t . The amount o f s a l mon and h e r r i n g e a t e n b y sea l i o n s and h a r b o u r s e a l s has b e en e s t i m a t e d i n A p p e n d i x • 1 . HISTORY OP PINNIPED FOOD HABIT STUDIES An e x t e n s i v e body o f l i t e r a t u r e d e a l s w i t h p i n n i p e d f e e d i n g h a b i t s , much o f I t about t h e p r o b l e m o f p r e d a t i o n upon c o m m e r c i a l l y v a l u a b l e f i s h s p e c i e s . The f o l l o w i n g summary i n c l u d e s t h e m a j o r p i n n i p e d f o o d h a b i t s t u d i e s c a r r i e d out i n w a t e r s o f w e s t e r n E u r o p e , N o r t h A m e r i c a and J a p a n . F o o d i t e m s - 2 -have b e e n d e s c r i b e d e i t h e r by t h e i r common names, or by b o t h common and s c i e n t i f i c names i n t h e s t u d i e s r e v i e w e d . F o r t h e sake o f c o n s i s t e n c y common names have been u s e d i n t h i s s t u d y . A p p e n d i x T a b l e I i n c l u d e s s c i e n t i f i c and common names o f a l l f o o d i t e m s r e f e r r e d t o . A. F e e d i n g h a b i t s o f s e a l s o u t s i d e B r i t i s h C o l u m b i a ' s S o a s t a l  w a t e r s Rae (i960) summarized t h e m a j o r s t u d i e s c a r r i e d o u t i n w e s t e r n E u r o p e and t h e B r i t i s h I s l e s . H j o r t and K r i p o w i t s c h (1907) and W o l l e b a e k (1907) c o n c l u d e d t h a t s e a l s on the N o r w e g i a n c o a s t were d e s t r o y i n g more s a l m o n t h a n were c a u g h t b y f i s h e r m e n i n t h a t a r e a , d u r i n g t h e e a r l y p a r t o f t h e t w e n t i e t h c e n t u r y . H a v i n g a (1933) e s t i m a t e d t h a t c o m m e r c i a l l y v a l u a b l e f i s h com-p r i s e d 75% o f t h e f o o d o f h a r b o u r s e a l s (Phoca v i t u l i n a ) i n D u t c h w a t e r s . Rae (i960) examined t h e p r e d a t o r y a c t i v i t y o f b o t h t h e h a r b o u r s e a l and t h e g r e y s e a l ( H a l i c h o e r u s g r y p u s ) i n t h e B r i t i s h I s l e s . He c o n c l u d e d t h a t t h e s e two s p e c i e s a n n u a l l y consumed an amount o f f i s h e q u i v a l e n t t o o n e - f i f t h t h e t o t a l a n n u a l B r i t i s h c a t c h f r o m i n s h o r e o r home w a t e r s . " F o o d i t e m s e a t e n by p i n n i p e d s on b o t h t h e A t l a n t i c and P a c i f i c c o a s t s o f N o r t h A m e r i c a ( e x c l u d i n g B r i t i s h C o l u m b i a ) , and i n t h e w e s t e r n P a c i f i c , a r e summarized i n A p p e n d i x T a b l e I I . T h i s t a b l e i l l u s t r a t e s t h e wide r a n g e o f f o o d s a v a i l a b l e . D e s -p i t e t h e l a r g e number o f f o o d i t e m s , however, e a c h p i n n i p e d u s u a l l y c o n c e n t r a t e s on a r e l a t i v e l y f ew i t e m s i n any g i v e n a r e a . The f u r s e a l ( C a l l o r h i n u s u r s i n u s ) has be e n s t u d i e d e x t e n s i v e l y i n b o t h t h e e a s t e r n and w e s t e r n P a c i f i c . Most c o l l e c t i o n s have b e e n made u n d e r t h e terms of two i n t e r n a t i o n a l programs of i n v e s t i g a t i o n : (a) In 1952 a one-year program was undertaken by Japan, the United States and Canada to study the d i s t r i b u t i o n , m i g r a t i o n and food h a b i t s of the f u r s e a l . (b) In 1957 r e p r e s e n t a t i v e s from Russia, Japan, the United States and Canada signed an " i n t e r i m Convention on Conservation of the North P a c i f i c Pur Seals". This convention, e f f e c t i v e f o r s i x years, was designed to i n v e s t i g a t e the numbers, m i g r a t i o n routes and w i n t e r i n g areas of the s e a l s , t h e i r f e eding habits.and e f f e c t s upon commercial f i s h , stocks and f i s h i n g gear. Before 1952, f u r s e a l c o l l e c t i o n s i n the western P a c i -f i c c o n s isted of 6 l stomachs (Taylor et al,., 1955). During 1952, under terms of the f i r s t i n t e r n a t i o n a l i n v e s t i g a t i o n , 1,138 stomachs w i t h food were examined from Japanese waters. Lantern f i s h and squid c o n t r i b u t e d 87$ by volume to these contents (Taylor e_t a J L . , 1955)- These authors concluded that s e a l pre-d a t i o n upon salmon was of o c c a s i o n a l and l o c a l s i g n i f i c a n c e only, but that f u r t h e r studies should be c a r r i e d out. Studies since 1958 (Anon., I 9 6 l ) i n d i c a t e that o f f Sanriku and Honshu l a n t e r n f i s h and squid c o n t r i b u t e d from 70 to 90$ by volume annually (3*3l+7 stomachs examined). Three hundred and seventy-tiro stomachs from the Sea of Japan and the Okhotsk Sea i n d i c a t e d that w h i t i n g was the most important food. In the western B e r i n g Sea. squid and salmonids formed 75$ by volume of the contents of 33 stomachs. Salmon con t r i b u t e d \\.2% by volume to the contents of 17 stomachs from the salmon f i s h i n g , grounds of the northwest P a c i f i c . No conclusions have as yet been drawn i n the present i n t e r n a t i o n a l i n v e s t i g a t i o n about the e f f e c t of f u r seals upon Japanese and Russian f i s h e r i e s . -k -I n t h e e a s t e r n P a c i f i c , A l e x a n d e r (1892) and L u c a s (1899) examined 1I4.O f u r s e a l stomachs f r o m t h e G u l f o f A l a s k a and B e r i n g S e a . S q u i d , salmon, w h i t i n g and r o c k f i s h were t h e most i m p o r t a n t f o o d i t e m s . S c h u l t z and R a f n (1936), May (1937) and Bonham (19^1) examined a t o t a l of 100 stomachs f r o m the W a s h i n g t o n c o a s t and f o u n d t h a t s q u i d and h e r r i n g were t h e two most i m p o r t a n t f o o d i t e m s . W i l k e and Kenyon (1951+) f o u n d t h a t h e r r i n g c o m p r i s e d o v e r 99$ hy volume o f t h e c o n t e n t s o f llj.8 s t omachs f r o m West C r a w f i s h I n l e t , A l a s k a . The f i r s t (1952) i n t e r n a t i o n a l p r o g r a m i n t h e e a s t e r n P a c i f i c f o u n d t h e f o l l o w i n g ( T a y l o r e t a l . , 1955): f r o m C a l i -f o r n i a t o W a s h i n g t o n c l u p e i d s , s m e l t s , a n c h o v y , hake, w h i t i n g and r o c k f i s h f o r m e d n e a r l y 70$ by volume o f t h e c o n t e n t s f r o m 125 s t o m a c h s . I n t h e G u l f o f A l a s k a c a p e l i n f o r m e d o v e r 90$ by volume o f t h e c o n t e n t s of l l 6 s t o m a c h s . No c o n c l u s i o n s were drawn d u r i n g t h e 1952 i n v e s t i g a t i o n a b o u t t h e p o s s i b l e e f f e c t o f f u r s e a l s on e a s t e r n P a c i f i c f i s h e r i e s . R e s u l t s f r o m t h e f i r s t f o u r y e a r s o f t h e sec o n d (1957) i n t e r n a t i o n a l i n v e s t i g a t i o n , e x c l u d i n g t h e B r i t i s h C o l u m b i a c o l l e c t i o n s , were as f o l l o w s (Anon., 1961): s e a l s w i n t e r i n g o f f C a l i f o r n i a f e e d m a i n l y on ancho v y , s a u r y , s q u i d and hake, w h i c h c o m p r i s e between 80 and 90$ o f t h e c o n t e n t s examined e a c h y e a r . I n Oregon w a t e r s a n c h o v y , hake and r o c k f i s h p r e d o m i n a t e i n s t o -machs. The W a s h i n g t o n sample i n d i c a t e d t h a t h e r r i n g , a n c h o v y and r o c k f i s h were the i m p o r t a n t f o o d i t e m s c o n t r i b u t i n g 67$ b y volume t o t h e c o n t e n t s examined. P i s c u s e_t a_l. (1961) s t a t e d t h a t t h e f u r s e a l c o u l d n o t be c o n s i d e r e d a s e r i o u s t h r e a t t o th e c o m m e r c i a l f i s h e r i e s o f C a l i f o r n i a , Oregon and W a s h i n g t o n . - 5 -I n A l a s k a h e r r i n g , c a p e l i n , w h i t i n g and s a n d l a n c e a r e th e i m p o r t a n t f o o d i t e m s and have c o n t r i b u t e d 93$ °y volume t o the t o t a l c o n t e n t s examined. N i g g o l e_t aJL. (i960) c o n c l u d e d t h a t f u r s e a l p r e d a t i o n upon c o m m e r c i a l l y v a l u a b l e f i s h i n A l a s k a n w a t e r s was of - n e g l i g i b l e i m p o r t a n c e . S m i t h (I90i|)and S t a r k s (1918), r e p o r t i n g on sea l i o n s " (E u m e t o p i a s .juhata and Z a l o p h u s c a l i f o r n i a n u s ) f r o m C a l i f o r n i a and Oregon,- f o u n d t h a t s q u i d , s k a t e , s h a r k and r o c k f i s h were the most i m p o r t a n t o f t h e i d e n t i f i e d f o o d s . Sea l i o n p r e d a t i o n upon s a l m o n a t t h e mouth o f t h e C o l u m b i a R i v e r c a u s e d "much damage". Iml.er and S a r b e r (19J4.7) examined 15 n o r t h e r n sea l i o n ( E u m e t o p i a s j_uba_ta) stomachs f r o m A l a s k a . Salmon, w h i t i n g and f l a t f i s h c o m p r i s e d 80$ o f t h e c o n t e n t s examined.' T h o r s t e i n s o n and L e n s i n k (1962) f o u n d t h a t s q u i d , o c t o p u s , r o c k f i s h and s a n d l a n c e p r e d o m i n a t e d I n $6 stomachs c o l l e c t e d a l o n g t h e A l a s k a p e n i n s u l a . M a t h i s e n et a_l. (1962) examined I l k s e a l i o n s f r o m C h e r n a b u r a I s l a n d , - A l a s k a . S q u i d , o c t o p u s , gr9enlings and s m e l t s were t h e most i m p o r t a n t f o o d i t e m s . Salmon o c c u r r e d once. H a r b o u r s e a l s on t h e A t l a n t i c c o a s t o f Canada f e e d m a i n l y on h e r r i n g , cod and f l a t f i s h , which, f o r m e d 59$ by volume of t h e c o n t e n t s i n a sample o f 201 stomachs ( F i s h e r and M a c k e n z i e , 1 9 5 5 ) « Templeman e_t a_l. (1957) r e p o r t e d t h a t c l u p e i d s , s a l m o n i d s , s m e l t s , cods' and f l a t f i s h e s were t h e f o o d i t e m s most o f t e n o b s e r v e d i n h a r b o u r s e a l stomachs f r o m N e w f o u n d l a n d and L a b r a d o r . I n W a s h i n g t o n S t a t e t h e h a r b o u r s e a l i s n o t b e l i e v e d t o consume l a r g e amounts of salmon, b u t may o f t e n cause f i n a n c i a l l o s s t o i n d i v i d u a l f i s h e r m e n ( S c h e f f e r , 1928; S c h e f f e r and S p e r r y , 1931; - 6 -S c h e f f e r and S l i p p , 19I4J+). C r u s t a c e a n s , h e r r i n g , c o d s , f l a t f i s h and s c u l p i n s f o r m e d 65$ hy o c c u r r e n c e o f t h e c o n t e n t s f r o m 95 s t o m a c h s . The h a r b o u r s e a l i n A l a s k a f e e d s e x t e n s i v e l y on e u l a c h o n i n t h e Cop p e r R i v e r a r e a and on h e r r i n g , salmon, e u l a -chon, cods and f l a t f i s h i n s o u t h e a s t A l a s k a ( I m l e r and S a r b e r , 19^-7). Prom o b s e r v a t i o n s made on damaged salmon t h e s e a u t h o r s e s t i m a t e d t h a t h a r b o u r s e a l s i n t h e Cop p e r R i v e r e s t u a r y d e s -t r o y e d an amount o f salmon e q u i v a l e n t t o two t o t h r e e p e r c e n t o f t h a t a r e a ' s t o t a l a n n u a l salmon c a t c h . B. F e e d i n g h a b i t s of s e a l s i n B r i t i s h C o l u m b i a w a t e r s 1. F u r s e a l s P u r s e a l stomachs f r o m B r i t i s h C o l u m b i a were f i r s t e xamined i n 1933 and 1935 (Clemens and W i l b y , 1933; Clemens, H a r t and W i l b y , 1936). T h e s e e a r l y s t u d i e s a t t e m p t e d t o a s s e s s th e r o l e o f f u r s e a l s i n t h e economy of t h e o c e a n o f f t h e Cana-d i a n P a c i f i c c o a s t . I n t h e 193 stomachs examined, h e r r i n g f o r m e d 8L$ by volume o f t h e c o n t e n t s and was o b v i o u s l y i m p o r t a n t i n th e d i e t o f s e a l s o f f s o u t h e r n V a n c o u v e r I s l a n d . These a u t h o r s s u g g e s t e d t h a t f u r t h e r s a m p l i n g was r e q u i r e d d u r i n g t h e e n t i r e m i g r a t o r y p e r i o d . They a l s o s t r e s s e d t h e i m p o r t a n c e o f knowing th e numbers o f m i g r a t i n g s e a l s , how l o n g t h e y r e m a i n e d i n B r i t i s h C o l u m b i a w a t e r s and t h e d a i l y f o o d r e q u i r e m e n t s o f e a c h s e a l . Between 1935 and 1958 no f u r s e a l stomachs f r o m B r i t i s h C o l u m b i a were examined. A l t h o u g h Canada was a member o f t h e f i r s t (1952) i n t e r n a t i o n a l p r o g r a m o f i n v e s t i g a t i o n m e n t i o n e d above, c o l l e c t i o n s were not made i n C a n a d i a n w a t e r s . D u r i n g th e s e c o n d (1957) i n t e r n a t i o n a l i n v e s t i g a t i o n Canada a g r e e d t o c o l l e c t b e t w e e n $00 and 7 5 ° s e a l s e a c h y e a r i n t h e n o r t h e a s t P a c i f i c . C o l l e c t i n g began i n 1958 and d u r i n g t h e f o u r y e a r s f r o m 1958 t o 196l> 1*520 stomachs were examined f r o m B r i t i s h C o l u m b i a c o a s t a l w a t e r s . I n o r d e r t o f u l f i l l Canada's q u o t a commitments an a d d i t i o n a l 500 s e a l s have b e e n c o l l e c t e d d u r i n g t h e f o u r y e a r s , i n W a s h i n g t o n o r A l a s k a n w a t e r s . C o l l e c t i o n s w i l l be c o n t i n u e d u n t i l 1963* a t l e a s t . 2. Sea l i o n s Sea l i o n s were f i r s t s t u d i e d i n B r i t i s h C o l u m b i a d u r i n g 1913 (Newcombe and Newcombe, 1913) and a g a i n d u r i n g 1915 (Newcombe Greenwood and P r a s e r , 1915)• A l t h o u g h few stomachs were exam-i n e d many f i s h e r m e n and f i s h i n g company o f f i c i a l s were i n t e r -v i e w e d . I n two a r e a s , t h e mouth of R i v e r s I n l e t and i n B a r k l e y Sound, sea l i o n s , when p r e s e n t i n l a r g e numbers, e v i d e n t l y a f f e c t e d t h e f i s h i n g i n d u s t r y . L i t t l e r e s e a r c h was done between I 9 l 6 and 1956, when an i n v e s t i g a t i o n was i n i t i a t e d by th e F i s h -merles R e s e a r c h B o a r d o f Canada t o g a t h e r i n f o r m a t i o n on the g e n e r a l b i o l o g y o f sea l i o n s . T h r e e h u n d r e d and s e v e n t y - f o u r stomachs have b e e n c o l l e c t e d s i n c e 1956. P i k e (1958)* r e p o r t i n g on 8 l stomachs c o l l e c t e d d u r i n g t h e e a r l y p a r t o f t h i s l a t t e r p r o g r a m , t e n t a t i v e l y c o n c l u d e d t h a t c o m m e r c i a l l y v a l u a b l e f i s h e s d i d n o t p l a y as i m p o r t a n t a r o l e I n t h e sea l i o n d i e t as was o f t e n c l a i m e d . 3. H a r b o u r s e a l s F i s h e r (1952) was t h e f i r s t t o i n v e s t i g a t e t h e l i f e h i s t o r y o f t h e h a r b o u r s e a l , i t s d i s t r i b u t i o n , numbers and f o o d h a b i t s , p a r t i c u l a r l y i n t h e Skeena R i v e r a r e a . E m p h a s i s was p l a c e d on the r o l e o f sal m o n i n t h e d i e t . H e r r i n g , s a l mon and - 8 -r o c k f i s h c o n t r i b u t e d 68$ b y volume t o t h e c o n t e n t s o f 27 s t o m a c h s . M o n e t a r y l o s s e s f r o m damaged c h i n o o k salmon, t h e s p e c i e s w h i c h s u f f e r e d most f r o m h a r b o u r s e a l a t t a c k , r e p r e -s e n t e d a p p r o x i m a t e l y s e v e n p e r c e n t of t h e t o t a l v a l u e of t h e c o m m e r c i a l . c a t c h ; f r o m a sample o f f i v e f i s h e r m e n . A l t h o u g h F i s h e r r e a l i z e d h i s s t u d y was n o t e x h a u s t i v e , he c o n c l u d e d t h a t h a r b o u r s e a l p r e d a t i o n upon Skeena R i v e r s a l m o n w a r r a n t e d some c o n t r o l . On h i s recommendations t h e D e p a r t m e n t o f F i s h e r i e s o f f i c i a l s u n d e r t o o k a c o n t r o l p r o g r a m c a r r i e d o ut d u r i n g J une o f e a c h y e a r when t h e h a r b o u r s e a l s were p u p p i n g on t h e Skeena R i v e r . F o r t y - f i v e stomachs were examined d u r i n g J une of 191+8 and 191+9 by c o n t r o l o f f i c i a l s . F i f t y - f o u r a d d i t i o n a l stomachs have b e e n c o l l e c t e d s i n c e 1958, when I j o i n e d t h e M a r i n e Mammal I n v e s t i g a t i o n o f t h e F i s h e r i e s R e s e a r c h B o a r d . METHODS AND MATERIALS A. S p e c i m e n c o l l e c t i o n 1. F u r s e a l F rom 1958 t o 196l C a n a d i a n r e s e a r c h v e s s e l s c o l l e c t e d 1,520 f u r s e a l stomachs between 1+8°00'N l a t i t u d e t o 5 5 ° 0 0'N l a t i t u d e d u r i n g t h e months o f J a n u a r y t o J u n e , i n c l u s i v e . O n l y 25 were c o l l e c t e d more t h a n 35 m i l e s f r o m t h e B r i t i s h C o l u m b i a c o a s t . S pecimens were c o l l e c t e d p e l a g i c a l l y , w h i l e e i t h e r w i n t e r i n g i n B r i t i s h C o l u m b i a w a t e r s , o r on t h e i r n o r t h -ward m i g r a t i o n t o t h e b r e e d i n g g r o u n d s i n t h e B e r i n g S ea. Quota commitments c e n t e r e d most h u n t i n g e f f o r t i n a r e a s of s e a l c o n c e n t r a t i o n s . L a r g e numbers o f s e a l s were c o l -l e c t e d b etween Cape F l a t t e r y and t h e n o r t h e r n t i p of V a n c o u v e r - 9 -I s l a n d . A s m a l l w i n t e r i n g p o p u l a t i o n o f a d u l t s i n H e c a t e S t r a i t was a l s o s a m p l e d . H u n t i n g , when w e a t h e r p e r m i t t e d , was c a r r i e d out as f o l l o w s : e a c h m o r n i n g t h e v e s s e l l e f t h a r b o u r and r a n out 25 t o I4.O m i l e s f r o m s h o r e , c o l l e c t i n g a l l s e a l s p o s s i b l e . D u r i n g t h e a f t e r n o o n t h e v e s s e l r e t u r n e d t o t h e c o a s t , w h i c h was r e a c h e d b y n i g h t f a l l . I n t h i s way t h e c o l l e c t i n g v e s s e l moved up and down t h e c o a s t , s e a r c h i n g f o r s e a l c o n c e n t r a t i o n s . The v e s s e l o c c a s i o n a l l y l a y one or more n i g h t s o f f s h o r e , p a r -t i c u l a r l y i f t h e w e a t h e r was f a v o u r a b l e . S e a l s were s i g h t e d f r o m t h e b r i d g e o f t h e v e s s e l ( F i g u r e l ) and were k i l l e d by means of a s h o t g u n w i t h S.S.G. s h o t o r a 3O.O6 r i f l e . F o r t u n a t e l y , dead f u r s e a l s do n o t s i n k r a p i d l y and o n l y about s i x p e r c e n t were l o s t due .to s i n k i n g . R e c o r d s i n c l u d e d t i m e , d a t e and l o c a t i o n of c a p t u r e , sex and b r e e d i n g c o n d i t i o n , a'nd^f e e d l n g : b e h a . v i o u r . Stomachs were removed, i n j e c t e d w i t h 10$ f o r m a l i n , p l a c e d i n c o t t o n s a c k s and s t o r e d i n wooden b a r r e l s c o n t a i n i n g 10$ f o r m a l i n . The p r e s e n c e o r a b s e n c e o f f o o d i n t h e stomach was n o t e d i n t h e l a b o r a t o r y and i f t h e stomach was n o t empty t h e f o l l o w i n g d a t a were r e c o r d e d : w e i g h t o f c o n t e n t s i n grams ( F i g u r e 3)> volume by d i s p l a c e m e n t ( c c ) , f o o d s p e c i e s and numbers of i n d i -v i d u a l s p r e s e n t . 2. Sea l i o n s Most s p e c i m e n s were c o l l e c t e d by F i s h e r i e s R e s e a r c h B o a r d p e r s o n n e l , a l t h o u g h D e p a r t m e n t o f F i s h e r i e s o f f i c i a l s s a v e d o r r e p o r t e d on s e v e r a l s t o m a c h s . I n a d d i t i o n , I accom-p a n i e d a c o m m e r c i a l e x p e d i t i o n f o r f i v e weeks d u r i n g t h e s p r i n g - 10 -Figure 1. M. V. " P a c i f i c Ocean", used e x t e n s i v e l y f o r c o l l e c t i n g f u r s e a l s , harbour seals and sea l i o n s . Figure 2. C o l l e c t i n g sea l i o n s , Scott I s l a n d s , 1959. - 12 -c c Merluceius productus Sebastodes maliqer gure 3. Analysis of stomach contents Top: examples from skeleton collection Bottom: weighing fur seal stomach contents. - 13 -o f 1959» c o l l e c t i n g s e a l i o n s f o r mink f o o d ; 115 stomachs were examined. Samples were c o l l e c t e d m a i n l y on t h e r o o k e r i e s o r h a u l - o u t r o c k s ( F i g u r e 2 ) ; c o l l e c t i n g a t sea was s e l d o m s u c -c e s s f u l as t h e a n i m a l s were e l u s i v e and s a n k r a p i d l y when k i l l e d . R i f l e s were u s e d e x c l u s i v e l y t o c o l l e c t s p e c i m e n s . D a t a c o l -l e c t e d were s i m i l a r t o t h o s e c o l l e c t e d f o r f u r s e a l s , e x c e p t t h a t volume by d i s p l a c e m e n t was n o t r e c o r d e d f o r t h e c o n t e n t s o f some stomachs examined i n t h e f i e l d . 3. H a r b o u r s e a l s The p r e s s u r e o f f u r s e a l and sea l i o n s t u d i e s has r e s t r i c t e d h a r b o u r s e a l r e s e a r c h , and few s p e c i m e n s a r e a v a i l -a b l e . M e s s r s D. and W. McNaughton of P e n d e r H a r b o u r , w o r k i n g i n c o n j u n c t i o n w i t h t h e D e p a r t m e n t of F i s h e r i e s , v e r y k i n d l y s a v e d a s u b s t a n t i a l sample o f 29 stomachs c o l l e c t e d i n the Queen C h a r l o t t e I s l a n d s d u r i n g t h e f a l l o f 1961. H a r b o u r s e a l s , w h i c h s i n k a l m o s t i m m e d i a t e l y upon b e i n g k i l l e d , were . c o l l e c t e d m a i n l y w h i l e swimming i n s h a l l o w w a t e r . Toward t h e end o f t h e c o l l e c t i n g p e r i o d , however, i t was f o u n d t h a t a good marksman i n a f a s t b o a t c o u l d k i l l and c o l l e c t s e a l s b e f o r e t h e y sank. D a t a r e c o r d e d f o r h a r b o u r s e a l s were s i m i l a r t o t h o s e r e c o r d e d f o r sea l i o n s . T a b l e I i n d i c a t e s numbers o f s p e c i m e n s c o l l e c t e d t h r o u g h o u t t h e c a l e n d a r y e a r . The f u r s e a l s were m a i n l y f e m a l e s , w h i l e b o t h s e x e s a r e r e p r e s e n t e d a p p r o x i m a t e l y e q u a l l y i n t h e h a r b o u r s e a l and sea l i o n s a m p l e s . -11+ -T a b l e I . M o n t h l y c o l l e c t i o n d a t e s f o r . a l l a v a i l a b l e h a r b o u r s e a l , f u r s e a l and s e a l i o n s tomachs. Month o f c o l l e c t i o n No. S p e c i m e n s C o l l e c t e d H a r b o u r s e a l F u r s e a l Sea l i o n J a n u a r y 1 17 --• F e b r u a r y 2 68 5 M a r c h 3 308 A p r i l 1 861 k May 1 7)+l 70 June 1+7 118 ^ 3 J u l y 9 81 A u g u s t 16 10 September 19 1+9 O c t o b e r 20 3 November 6 11+ December l T o t a l s 126 2,113 393 B. A n a l y s i s o f sto m a c h c o n t e n t s An e x a m i n a t i o n o f s t o m a c h c o n t e n t s i s t h e f a v o u r e d method o f i n v e s t i g a t i n g p i n n i p e d f e e d i n g h a b i t s . S c a t s and spewin g s have b e e n n o t e d o c c a s i o n a l l y ( S c h e f f e r and S l i p p , 191+1+; S c h e f f e r , 1950; W i l k e and Kenyon, 1952; W i l k e and Kenyon, 1951+), h ^ t t h e y a r e s e l d o m f o u n d . Most f o o d i t e m s a r e consumed under w a t e r and s i g h t o b s e r v a t i o n s a r e few ( S c h e f f e r , 1950). Hynes (1950)> o u t l i n i n g t h e s e v e r a l p o s s i b l e methods of a n a l y s i n g f i s h s t o m a c h c o n t e n t s , has a l s o c o v e r e d t h e p o s s i b l e a n a l y s e s f o r p i n n i p e d s . The c a r n i v o r o u s f e e d i n g h a b i t s o f most f i s h and p i n n i p e d s , i n an a q u a t i c e n v i r o n m e n t , l e a d s - t o s i m i l a r p r o b l e m s i n a s s e s s i n g s t o m a c h c o n t e n t s . These s e v e r a l methods a r e d i s -c u s s e d b e l o w . - 15 -1. D e g r e e o f f u l l n e s s . A n a r b i t r a r y e s t i m a t e o f t h e f u l l n e s s o f t h e stoma c h h a s b e e n u s e d t o d e m o n s t r a t e s e a s o n a l v a r i a t i o n s i n f o o d i n t a k e 2. Numbers o f i n d i v i d u a l s T o t a l numbers o f i n d i v i d u a l s o f e a c h f o o d i t e m a r e t a b u l a t e d and may be e x p r e s s e d as p e r c e n t a g e s o f a l l f o o d o r g a n i s m s f o u n d i n t h e s a m p l e . T h i s i s an u n s a t i s f a c t o r y t e c h n i q u e f o r a p r e d a t o r whose s i z e o f p r e y r a n g e s f r o m a s t i c k l e b a c k t o a t e n - p o u n d s a l m o n . 3* D o m i n a n t i t e m s The number o f s t o m a c h s i n w h i c h each, f o o d i t e m o c c u r s as t h e d o m i n a n t f o o d s t u f f i s e x p r e s s e d as a p e r c e n t f r e q u e n c y o f o c c u r r e n c e . h' P o i n t s P o o d i t e m s i n e a c h s t o m a c h a r e l i s t e d as common, f r e -q u e n t , e t c . , on t h e b a s i s o f r o u g h c o u n t s o r j u d g e m e n t s made' hy e y e , and e a c h c a t e g o r y i s t h e n a l l o t e d a number o f p o i n t s . A l l p o i n t s g a i n e d by e a c h f o o d I t e m a r e t h e n summed and p e r -c e n t a g e c a l c u l a t i o n s may be made. 5« Volume and w e i g h t s T h i s m e thod, and t h e f'fol.low'i'ng; one, have b e e n t h e c u s t o m a r y t e c h n i q u e s f o r h a n d l i n g p i n n i p e d s t o m a c h c o n t e n t s . The w e i g h t o f e a c h f o o d i t e m i n e a c h s t o m a c h i s c a l c u l a t e d i n e i t h e r o f two w a y s : ( a ) t h e i t e m s i n e a c h s t o m a c h a r e s e p a r a t e and w e i g h e d ; ( b ) an e s t i m a t i o n b y eye i s made o f t h e p e r c e n t a g e c o n t r i b u t i o n o f e a c h i t e m t o t h e c o n t e n t s o f e a c h s t o m a c h ; t h i s p e r c e n t a g e i s t h e n a p p l i e d t o t h e known w e i g h t o f t h e c o n t e n t s o f t h e s t o m a c h , t o e s t i m a t e t h e w e i g h t o f t h e i n d i v i d u a l i t e m . - 1 6 -The w e i g h t s o f e a c h r e s p e c t i v e f o o d i t e m i n t h e sample a r e t h e n summed and may be e x p r e s s e d as a p e r c e n t a g e o f t h e t o t a l c o n -t e n t s e xamined. Volume a n a l y s e s a r e c a r r i e d out i n a s i m i l a r ; f a s h i o n t o t h a t d e s c r i b e d f o r t h e w e i g h t a n a l y s i s , e x c e p t t h a t volume by d i s p l a c e m e n t i s measured, r a t h e r t h a n w e i g h t . Stomach c o n t e n t p e r c e n t a g e s i n b o t h i n t e r n a t i o n a l f u r s e a l programs have been c a l c u l a t e d on a p e r c e n t b y volume b a s i s ( T a y l o r e_t a l . , 1 9 5 5 ; Anon., I 9 6 l ) . The w e i g h t method o f a n a l y s i s has b e e n m o d i f i e d ( R i c k e r , 1 9 3 7 » B o g o r o v , i 9 6 0 ) by m u l t i p l y i n g t h e numbers o f o r g a n i s m s o f e a c h i t e m i n t h e s t o m a c h by the known mean l i v e w e i g h t o f t h a t i t e m . T h i s g i v e s a w e i g h t o f e a c h k i n d o f f o o d e a t e n , r a t h e r t h a n a w e i g h t of e a c h i t e m o f f o o d i n t h e s t o m a c h a t t h e t i m e t h e p r e d a t o r was k i l l e d . A t h i r d m o d i f i c a t i o n of t h e volume o r w e i g h t method I s t o sum t h e p e r c e n t a g e s e a c h i t e m c o n t r i b u t e s t o e a c h stomach. 6 . Number o f o c c u r r e n c e s The number o f stomachs i n w h i c h e a c h f o o d i t e m o c c u r s i s t a b u l a t e d ; t h e s e o c c u r r e n c e s may be summed and e x p r e s s e d as p e r c e n t a g e s o f t h e t o t a l o c c u r r e n c e s o f a l l f o o d i t e m s . Two methods, number o f o c c u r r e n c e s and t h e volume o r w e i g h t method, were c o n s i d e r e d f o r t h i s s t u d y . R i c k e r ' s ( 1 9 3 7 ) m o d i f i c a t i o n s o f t h e w e i g h t a n a l y s i s g i v e t h e most a c c u r a t e a n a l y s i s i f (a) numbers of i n d i v i d u a l s of e a c h i t e m can be d e t e r m i n e d , and (b) i f p r e y s i z e s can be e s t i m a t e d a c c u r a t e l y . The numbers of i n d i v i d u a l s can be c o u n t e d , b u t s i z e o f p r e y i s e x t r e m e l y d i f f i c u l t t o e s t i m a t e f r o m p i n n i p e d s t o m a c h c o n t e n t s . O n l y r a r e l y does one f i n d , as i n F i g u r e $, - 17 -a s t o m a c h i n w h i c h l e n g t h s or w e i g h t s of t h e p r e y c a n be t a k e n d i r e c t l y . L a r g e f i s h a r e s w a l l o w e d p i e c e m e a l , and as p o i n t e d out l a t e r , h e a ds may be d i s c a r d e d . E s t i m a t e s o f l e n g t h , t h e r e -f o r e , c a n o n l y be made f r o m t h e b r o k e n r e m a i n s o f v e r t e b r a l c o l u m n s . F i n a l l y , e s t i m a t e s of s q u i d and o c t o p u s w e i g h t s f r o m beak s i z e i s o n l y j u s t r e c e i v i n g a t t e n t i o n ( C l a r k e , 1962(a); C l a r k e , 1 9 6 2(b)); a t p r e s e n t t h e r e i s no i n f o r m a t i o n a b o u t beak s i z e and body w e i g h t of t h e s q u i d s and o c t o p u s e s f o u n d i n p i n n i p e d stomachs c o l l e c t e d f r o m B r i t i s h C o l u m b i a w a t e r s . F o r t h e s e r e a s o n s I c o n c l u d e d t h a t t h e a n a l y s e s must e i t h e r be b a s e d on t h e a c t u a l volume o r w e i g h t s of t h e stomach c o n t e n t s , o r a f r e q u e n c y o f o c c u r r e n c e o f t h e i n d i v i d u a l i t e m s . Hynes (1950) h a s shown t h a t any o f t h e commonly a c c e p t e d methods o f a s s e s s i n g t h e c o m p o s i t i o n o f an a n i m a l ' s d i e t w i l l g i v e much the same r e s u l t s , i f t h e d a t a a r e s c a l e d down t o p e r c e n t a g e s , and i f l a r g e samples a r e u s e d . T h i s p o i n t , w i t h one e x c e p t i o n i s i l l u s t r a t e d i n F i g u r e 1+, showing t h e 1958 t o 1961 f u r s e a l sample (volume d a t a f r o m P i k e e t a l . , 1958, 1959, I960, 1961). The one m a j o r e x c e p t i o n , s q u i d , c o n -t r i b u t e s o n l y I}..7$ h y volume b u t 22.3$ by o c c u r r e n c e t o t h e sample. S q u i d r e m a i n s , u s u a l l y c o n s i s t i n g o f beaks and eye l e n s e s , d i f f e r m a r k e d l y f r o m f i s h r e m a i n s , w h i c h u s u a l l y i n c l u d e more f l e s h . O c t o p u s f l e s h was r a r e l y f o u n d i n sea l i o n s tomachs. The l a c k o f c e p h a l o p o d f l e s h i n d i c a t e s t h a t e i t h e r s q u i d or o c t o p u s were p r e y e d upon e a r l i e r i n t h e m o r n i n g t h a n f i s h , or t h e i r f l e s h was d i g e s t e d more r a p i d l y t h a n f i s h f l e s h . How-ever., t h e d i s c r e p a n c i e s between t h e s e two c a l c u l a t i o n s a r e e x p l a i n e d , and u n t i l e v i d e n c e t o t h e c o n t r a r y i s p r o d u c e d , I Figure 4. Comparison between a per cent by occurrence a n a l y s i s and a per cent by volume a n a l y s i s of contents from 869 fur s e a l stomachs (1958-1961 data). Figure 5. Small black cod found i n fur s e a l stomach. - 20 -b e l i e v e t h e h i g h e r v a l u e , b a s e d on o c c u r r e n c e , i s the more m e a n i n g f u l c a l c u l a t i o n . A v o l u m e t r i c o r w e i g h t a n a l y s i s o f a s m a l l sample i s p a r t i c u l a r l y s u s c e p t i b l e t o f a u l t y i n t e r p r e t a t i o n . As shown l a t e r , sea l i o n s and f u r s e a l s f e e d m a i n l y d u r i n g t h e e a r l y m o r n i n g . Thus, stomachs c o l l e c t e d i n t h e m o r n i n g a r e f u l l w h i l e t h o s e c o l l e c t e d t o w a r d s n i g h t f a l l a r e empty. The c o n t e n t s f r o m one st o m a c h c o l l e c t e d a t d a y b r e a k w i l l o u t w e i g h t h e c o n -t e n t s f r o m many stomachs c o l l e c t e d l a t e r i n t h e day, and t h e i t e m o r i t e m s i n t h e f o r m e r s t o m a c h w i l l have an e x a g g e r a t e d i m p o r t a n c e i n a p e r c e n t a g e b y w e i g h t a n a l y s i s . P e r c e n t a g e s b a s e d on f r e q u e n c y o c c u r r e n c e c a l c u l a t i o n s a v o i d s u c h e r r o r s . E a c h i t e m e n c o u n t e r e d i n a stomach i s g i v e n one p o i n t , r e g a r d l e s s o f t h e w e i g h t of t h a t i t e m . I f t h e p r e -d a t o r a t e two or more i t e m s , b u t c o n s i s t e n t l y c hose more o f one i t e m t h a n t h e o t h e r s , a f r e q u e n c y o f o c c u r r e n c e a n a l y s i s would e x a g g e r a t e t h e I m p o r t a n c e o f t h a t i t e m e a t e n i n l e s s e r amounts. R i c k e r (1937), e x a m i n i n g t h e f o o d p r e f e r e n c e s o f young s o c k e y e s a l mon i n the l a b o r a t o r y , f o u n d t h a t two e q u a l l y a b u n d a n t f o o d i t e m s were e a t e n , b u t one i t e m was c o n s i s t e n t l y t a k e n more o f t e n t h a n t h e o t h e r . A f r e q u e n c y o f o c c u r r e n c e a n a l y s i s would e x a g g e r a t e t h e i m p o r t a n c e of t h a t i t e m t a k e n i n l e s s e r amounts. However, t h e r e i s no e v i d e n c e f o r s u c h a c o n s i s t e n t s e l e c t i o n i n f a v o u r o f one f o o d i t e m b y e i t h e r f u r s e a l s , sea l i o n s or h a r b o u r s e a l s . T a y l o r e_t aJL. (1955) c o n c l u d e d t h a t f u r s e a l s were n o n - s e l e c t i v e i n t h e i r f e e d i n g h a b i t s , and t e n d e d t o p r e y on t h a t i t e m w h i c h was e a s i e s t t o c a t c h a t t h e moment. The f o l l o w i n g two o b s e r v a t i o n s s u p p o r t t h i s c o n c l u s i o n - 2 1 -f o r a l l t h r e e s p e c i e s s t u d i e d ? (a) E a c h p r e d a t o r u s u a l l y -r e s t r i c t e d i t s e l f t o one p r e y i t e m p-er f e e d ( a c t u a l f i g u r e s w e r e : f u r s e a l s , 7 7 $ of stomachs w i t h f o o d c o n t a i n e d o n l y one i t e m ; sea l i o n s , 7 8 $ of stomachs w i t h f o o d had o n l y one i t e m ; h a r b o u r s e a l s , 7 6 $ o f stomachs w i t h f o o d c o n t a i n e d o n l y one i t e m ) . (b) I n t h e t o t a l o f 3 3 i d e n t i f i e d f o o d i t e m s o n l y f o u r ( l a m p r e y , sea p e r c h , c a b e z o n and s k a t e ) had n o t a t one t i m e o r a n o t h e r b e e n t h e s o l e i t e m i n a stomach. Thus, s e a l s and sea l i o n s on t h e B r i t i s h C o l u m b i a c o a s t p r e y m a i n l y on one i t e m p e r f e e d , and have a wide r a n g e o f p o s s i b l e f o o d i t e m s t o c h o o s e f r o m . Abundance o f p r e y may i n f l u e n c e t h e p r e d a t o r i n i t s c h o i c e o f f o o d . P i k e ejb a_l. ( 1 9 6 1 ) r e p o r t e d t h a t a m i d - w a t e r t r a w l f i s h i n g a t 2 8 - 3 6 f a t h o m s c a u g h t a n c h o v y and e u l a c h o n i n a p p r o x i m a t e l y e q u a l amounts, p l u s a few h e r r i n g ; t h e s t o m a c h c o n t e n t s o f a f u r s e a l c o l l e c t e d a t t h e same t i m e i n t h e same, p o s i t i o n c o n s i s t e d of $0% e u l a c h o n and $0% a n c h o v y , t h e two most a b u n d a n t s p e c i e s i n t h e a r e a . To summarize, u n d e r t h e c i r c u m s t a n c e s d e s c r i b e d above p e r c e n t f r e q u e n c y o f o c c u r r e n c e w i l l g i v e a p p r o x i m a t e l y t h e same r e s u l t s as p e r c e n t b y volume ( o r w e i g h t ) i n a l a r g e sample, b u t a more r e a l i s t i c and u n b i a s e d i n t e r p r e t a t i o n o f a s m a l l s a m p l e . P e r c e n t f r e q u e n c y o f o c c u r r e n c e c a l c u l a t i o n s have been c a r r i e d out as f o l l o w s : t h e number o f t i m e s a g i v e n i t e m o c c u r r e d has b e e n e x p r e s s e d as a p e r c e n t a g e of t h e t o t a l number o f o c c u r r e n c e s o f i d e n t i f i a b l e f o o d i t e m s i n the sample. An example f r o m T a b l e V I I (page 51) w i l l c l a r i f y t h i s : n i n e t y -two stomachs w i t h f o o d were c o l l e c t e d f r o m sea l i o n b r e e d i n g - 22 -c o l o n i e s d u r i n g t h e summer. I n t h i s sample, l l | . d i f f e r e n t i t e m s were e n c o u n t e r e d 85 t i m e s ; r o c k f i s h , o c c u r r i n g 11 t i m e s ( i . e . , i n 11 s t o m a c h s ) c o n t r i b u t e d 12.9$ t o t h e t o t a l d i e t i n t h a t a r e a . C. I d e n t i f i c a t i o n o f stomach c o n t e n t s A f i s h s k e l e t o n c o l l e c t i o n was begun d u r i n g t h e e a r l y w i n t e r of 1958 and s p e c i m e n s were added when n e c e s s a r y . F r o z e n o r s a l t e d s p e c i m e n s were g e n t l y b o i l e d , t h e f l e s h removed and a l l bones s a v e d . An a t t e m p t was made t o keep the s k u l l and v e r t e b r a l column i n t a c t as i t was f o u n d t h e v e r t e b r a e and v e r t e b r a l column were t h e most u s e f u l a i d s i n i d e n t i f i c a t i o n o f s t omach c o n t e n t s ( F i g u r e 3 )« T o t a l v e r t e b r a l c o u n t s , r e l a -t i v e p o s i t i o n s o f f i r s t h a e m a l a r c h and s p i n e s , and m o d i f i c a -t i o n s o f p a r a p o p h y s e s and z y g a p o p h y s e s were p a r t i c u l a r l y u s e f u l i n t h e i d e n t i f i c a t i o n of f i s h s p e c i e s . F i s h i d e n t i f i c a t i o n was a i d e d by t h e f o l l o w i n g pub-l i c a t i o n s : Chapman, 191+1; Chapman, 19M+; Clemens and W i l b y , 1961; C l o t h i e r , 1950; G r e g o r y , 1933; H a r t and McIIugh, 1 9 ^ ; Sunde and L i n d s e y , 1958. S c i e n t i f i c n o m e n c l a t u r e and o r d e r o f a r r a n g e m e n t f o l l o w s Clemens and W i l b y (1961). I n e v e r s u c c e e d e d i n s a t i s f a c t o r i l y i d e n t i f y i n g a l l s q u i d and o c t o p u s r e m a i n s w h i c h u s u a l l y c o n s i s t e d of be a k s o n l y . I d e n t i f i c a t i o n o f whole s q u i d s was f a c i l i t a t e d b y r e f e r e n c e t o B e r r y (1912). One sample was s e n t t o t h e U n i t e d S t a t e s F i s h and W i l d l i f e S e r v i c e i n S e a t t l e f o r i d e n t i f i c a t i o n . - 2 3 -DISTRIBUTION, NUMBERS AND MIGRATORY BEHAVIOUR A. G e n e r a l h a b i t a t d e s c r i p t i o n A d e s c r i p t i o n o f t h e s e v e r a l h a b i t a t s f r e q u e n t e d b y f u r s e a l s , s e a l i o n s and h a r b o u r s e a l s i s i n c l u d e d t o h e l p u n d e r s t a n d t h e d i f f e r e n c e s and s i m i l a r i t i e s i n f o o d h a b i t s d i s -c u s s e d b e l o w . Rugged p r o m o n t o r i e s , p e n i n s u l a s and i s l a n d s b r e a k up t h e B r i t i s h C o l u m b i a c o a s t a l w a t e r s I n t o numerous s t r a i t s , g u l f s , b a y s and i n l e t s o f v a r y i n g s h apes and d e p t h s , and have r e s u l t e d i n a c o a s t l i n e o f an e s t i m a t e d 1 6 , 9 0 0 m i l e s ( S c a g e l , 1 9 6 l ) . I n a d d i t i o n , t h e r e a r e many r i v e r s e m p t y i n g I n t o t h e s e a , c r e a t i n g e s t u a r i n e c o n d i t i o n s . T h e s e e n v i r o n m e n t s may be r o u g h l y d i v i d e d i n t o f o u r c a t e g o r i e s , t h e f i r s t two o f w h i c h have a l r e a d y b e e n d e s c r i b e d (Cowan and G u i g u e t , 1 9 5 6 ) : ( 1 ) P e l a g i c w a t e r s b i o t i c a r e a - w a t e r s o u t s i d e any p r o t e c t i o n f r o m l a n d and open t o t h e f u l l f o r c e o f a l l o c e a n o g r a p h i c a l and m e t e o r o l o g i c a l c h a n g e s . ( 2 ) C o a s t w a t e r s b i o t i c a r e a -b o d i e s o f w a t e r l y i n g b e h i n d , and p r o t e c t e d by, i s l a n d s , p o i n t s o r r e e f s . ( 3 ) E s t u a r i e s - r i v e r mouths where a m i x i n g o f s a l t and f r e s h w a t e r o c c u r s . ( I 4 . ) F r e s h w a t e r - c o a s t a l r i v e r s , and l a k e s c o n n e c t e d t o t h e m a r i n e e n v i r o n m e n t by r i v e r s . T a b l e I I o u t l i n e s t h e d i s t r i b u t i o n o f p i n n i p e d s on t h i s c o a s t i n r e l a t i o n t o t h e above f o u r e n v i r o n m e n t s . F u r s e a l s a r e s e l d o m f o u n d w i t h i n 5 m i l e s f r o m t h e c o a s t ; i n c o m p a r i s o n , s e a l i o n s and h a r b o u r s e a l s a r e r a r e l y f o u n d f a r t h e r t h a n 5 m i l e s f r o m s h o r e . - 21+ -Table I I . C o a s t a l h a b i t a t s and p i n n i p e d d i s t r i b u t i o n . H a b i t a t S e a l or sea l i o n s present P e l a g i c waters b i o t i c area 3oast waters b i o t i c area E s t u a r i e s F r e s h water f u r s e a l x sea l i o n f u r s e a l harbour s e a l x sea l i o n x f u r s e a l harbour s e a l x sea l i o n harbour s e a l x I n d i c a t e s area of g r e a t e s t p r e f e r e n c e 1 . Fur s e a l s The f u r s e a l m i g r a t i o n i s one of the best documented mi g r a t i o n s of marine mammals (Jordan, 1 8 9 9 ; Kenyon and Wilke, 1 9 5 3 ; : T a y l o r et a l . , 1 9 5 5 ) « The mature cows, young males and females, and the f o u r - and five-month-old pups leave the P r i b i l o f I s l a n d s In the B e r i n g Sea d u r i n g l a t e October and November. Many move as f a r south as southern C a l i f o r n i a i n the e a s t e r n P a c i f i c , and southern Japan i n the western P a c i f i c . In the s p r i n g they r e t u r n t o the P r i b i l o f s , a r r i v i n g i n June and J u l y , h a v i n g covered a d i s t a n c e of up to 6 , 0 0 0 miles each year on t h e i r round t r i p . Males, except f o r the one-and two-year-olds, and many t h r e e - and f o u r - y e a r - o l d s , remain i n the B e r i n g Sea and n o r t h e r n G u l f of A l a s k a a l l y e a r . From p u b l i s h e d l i f e t a b l e s (Abegglen et a l . , i 9 6 0 ) the P r i b i l o f s e a l herd c o n s i s t s of approximately 1 , 2 5 0 , 0 0 0 females and 1 + 0 0 , 0 0 0 males one to f o u r years of age. Th e r e f o r e , approximately 1 , 6 5 0 , 0 0 0 f u r s e a l s move south from the B e r i n g Sea each f a l l , i n t o the North P a c i f i c . Some of these, perhaps a r e l a t i v e l y l a r g e per cent, w i n t e r i n waters w i t h i n 1 5 0 miles - 2 5 -o f f e i t h e r t h e A m e r i c a n o r A s i a n l a n d masses. S e a l c o n c e n t r a t i o n s i n t h e e a s t e r n P a c i f i c have b e e n s t u d i e d by t h e U n i t e d S t a t e s and C a n a d i a n i n v e s t i g a t o r s f r o m s o u t h e r n C a l i f o r n i a t o t h e B e r i n g S e a . O l d e r f e m a l e s move f a r t h e r s o u t h , and few one-, two- and t h r e e - y e a r - o l d m a l e s o r f e m a l e s t r a v e l s o u t h o f W a s h i n g t o n . R e l a t i v e l y h i g h c o n c e n t r a -t i o n s o f y o u n g e r s e a l s a r e f o u n d i n some B r i t i s h C o l u m b i a c o a s t a l w a t e r s . T h e s e s e a l s f i r s t a p p e a r i n December and b y J a n u a r y may be f o u n d i n H e c a t e S t r a i t , Queen C h a r l o t t e Sound and t h e i n s i d e c h a n n e l s and i n l e t s o f n o r t h e r n B r i t i s h C o l u m b i a . The m a j o r i t y r e m a i n i n t h e s e w a t e r s u n t i l t h e end o f A p r i l , and some s t r a g g l e r s may s t i l l be f o u n d d u r i n g J u n e and J u l y . S o u t h o f B r i t i s h C o l u m b i a , p a r t i c u l a r l y o f f C a l i f o r n i a , t h e r e a r e h e a v y c o n c e n t r a t i o n s o f mature f e m a l e s , w h i c h f i r s t a p p e a r i n December ( T a y l o r e_t a _ l . , 1 9 5 5 » Anon, 1 9 6 l ) . D u r i n g t h e s p r i n g most s e a l s b e g i n t h e i r r e t u r n t o t h e P r i b i l o f I s l a n d s . Many y e a r l i n g s , however, and some two-and t h r e e - y e a r - o l d s r e m a i n a t sea t h e e n t i r e y e a r . The n o r t h -ward m o v i n g h e r d o f a d u l t cows f i r s t a p p e a r s o f f s o u t h e r n V a n c o u v e r I s l a n d d u r i n g l a t e M arch; t h e g r e a t e s t numbers o f t h e s e s e a l s a r e e n c o u n t e r e d b e t w e e n t h e m i d d l e o f A p r i l and t h e m i d d l e o f May, p a s s i n g by i n a s e r i e s o f waves f r o m f i v e t o 3 5 m i l e s o f f s h o r e . S u f f i c i e n t i n f o r m a t i o n I s n o t a v a i l a b l e t o e s t i m a t e a c c u r a t e l y t h e numbers o f s e a l s m i g r a t i n g t h r o u g h o r w i n t e r i n g i n B r i t i s h C o l u m b i a c o a s t a l w a t e r s . 2 . Sea l i o n s The s e a l i o n m i g r a t i o n s a r e n o t f u l l y u n d e r s t o o d a t - 2 6 -present, although i t i s known that much of the population undergoes a seasonal movement. In contrast to the fur seals, where the longest migration i s undertaken by the females and young males, the sea l i o n cows with pups apparently remain on the rookeries throughout the entire year; males one year and older move from the exposed rookeries into the i n l e t s or to rocks closer to more sheltered bodies of water. Barren cows and impregnated cows which have l o s t t h e i r pups on the rookeries may also move inshore with the males. Winter counts indicate that over hal f the breeding population gradually leaves the rookeries following pupping and breeding. A population of 1,600 animals on the Scott Islands during September, I 9 6 0 , had dwindled to only 700 (mostly cows and pups) by January, 1961; 200 animals on Cape St. James i n A p r i l , 1962, had increased to 600 by May 31, 1962. A census i n 1956 indicated 11,000 to 12,000 sea li o n s (~5$) o n the B r i t i s h Columbia coast (Pike and Maxwell, 1957). During 1959 and i960 the Department of F i s h e r i e s reduced these numbers by sending out several hunting parties of t h e i r own, and by encouraging k i l l i n g for mink or pet food. A census taken during the summer of 1961 (unpublished data, F i s h e r i e s Research Board of Canada) indicated there were approximately 1,500 pups and l+,500 adults resident i n B r i t i s h Columbia waters. During the summer months approximately 70$ of t h i s population, or 3»100 adults, concentrate on the two rookeries of Cape St. James and the Scott Islands (Pike and Maxwell, 1957). 3. Harbour seals This species i s regarded as non-migratory i n the sense - 2 7 -o f a s e a s o n a l exodus and r e t u r n o f a l l o r a l a r g e p a r t o f t h e p o p u l a t i o n I n t o o r o u t o f t h e p o p u l a t i o n a r e a . However, P i s h e r ( 1 9 5 2 ) n o t i c e d a movement i n t o and up t h e Skeena R i v e r f o l l o w i n g s a l m o n , w h i l e b o u n t y h u n t e r s have n o t i c e d t h a t many s e a l s h e r d t o g e t h e r i n s m a l l g r o u p s d u r i n g t h e e a r l y summer. F u t u r e s t u d i e s w i l l d e t e r m i n e t h e e x t e n t o f h a r b o u r s e a l movements, b u t p r e s e n t i n f o r m a t i o n i n d i c a t e s no m i g r a t i o n c o m p a r a b l e t o t h a t o f e i t h e r t h e f u r s e a l o r t h e s e a l i o n . A h a r b o u r s e a l c e n s u s h a s n e v e r b e e n c o n d u c t e d a l o n g t h e B r i t i s h C o l u m b i a c o a s t . However, o b s e r v a t i o n s made on f i e l d t r i p s s i n c e 1 9 5 8 s u g g e s t t h a t d u r i n g t h e f a l l and w i n t e r , when t h e s e a n i m a l s a r e w i d e l y d i s p e r s e d , t h e r e may be as many as one s e a l p e r m i l e o f s h o r e l i n e , o r 1 7 , 0 0 0 s e a l s . B o u n t y h u n t e r s (D. McNaughton) have e s t i m a t e d t h e r e a r e a p p r o x i m a t e l y 2 0 , 0 0 0 h a r b o u r s e a l s on t h i s c o a s t . To summarize, t h e r e a r e 6 , 0 0 0 ( — 5 $ ) s e a l i o n s and an e s t i m a t e d 1 7 , 0 0 0 t o 2 0 , 0 0 0 h a r b o u r s e a l s r e s i d e n t i n B r i t i s h C o l u m b i a ' s c o a s t a l w a t e r s . I n a d d i t i o n t h e r e I s an unknown number o f f u r s e a l s , some o f w h i c h w i n t e r and some o f w h i c h m i g r a t e t h r o u g h t h e s e w a t e r s . C o n f i d e n c e l i m i t s c a n n o t be a t t a c h e d t o t h e e s t i m a t e of h a r b o u r s e a l numbers as r e p e a t e d c o u n t s a r e n o t a v a i l a b l e . - 2 8 -COMPARATIVE ANATOMY The comparative anatomy of the digestive t r a c t , including the dentition, was examined to add to our understanding of feeding habits. A. Dentition 1 . Sea li o n s The formula f o r o t a r i i d milk d e n t i t i o n (V. B. Scheffer, personal communication) i s : A , 1 - 2 - 3 , 1 0 - 2 - 3 - k d i o - 2 - 3 ' d c T ' d m — 2 - 3 - it Permanent d e n t i t i o n i s : 1 - 2 - 3 1 1 - 2 - 3 - U - 5 0 - 2 - 3 * 1* 1 - 2 - 3 - 4 - 5 By the end of September, at approximately three and a h a l f months af t e r b i r t h , a l l the permanent de n t i t i o n i s e v i -dent except f o r the two upper and lower canines, which are s t i l l represented by deciduous teeth. Figure 6 shows the permanent de n t i t i o n at t h i s stage as well as the three deciduous post canines s t i l l adhering to gum tissue beside the permanent teeth. The deciduous canines p e r s i s t u n t i l February and March when the young sea lio n s are eight to nine months old. One male s k u l l , collected March 8 , 1 9 6 l , had two upper canines protruding f i v e mm through the gum, the lower l e f t canine was through two mm, and the lower r i g h t was not showing (Figure 7 K Figure 6 i l l u s t r a t e s the permanent dentition at 1 5 months of age. The l a s t post canine i s double rooted, while a l l others are single rooted; crowns are i r r e g u l a r l y conical. - 29 -Figure 6. Top: 3-4-month-old male sea l i o n s k u l l Bottom: 15-month-old female sea l i o n s k u l l (b = deciduous teeth) Figure 7. Top: lower jaw from 9-month-old male sea l i o n , showing permanent canines Center: young female harbour s e a l s k u l l Bottom: 9-month-old female f u r s e a l s k u l l - 31 -The lower post canines, p a r t i c u l a r l y the t h i r d and fourth, have very s l i g h t accessory cusps. Canines of both jaws are large. The two outer upper i n c i s o r s are canine-like i n form and three-quarters as long as the canines. 2. Fur seals The o t a r i i d dental formula (see above) i s applicable to f u r seals. At b i r t h a l l the permanent de n t i t i o n i s evident except f o r the s i x t h upper post canine (Kuboto and Komuro, 196l). This appears shortly a f t e r b i r t h . Figure 7 i l l u s t r a t e s the permanent de n t i t i o n at eight months of age. These permanent teeth are haplodont, with canines and i n c i s o r s single rooted, and the post canines incom-p l e t e l y double rooted (Allen, 1880). The canines are large and the outer upper i n c i s o r i s s l i g h t l y enlarged. 3. Harbour seals No f o e t a l or skulls of pups were examined In this study. The dental pattern i s as follows (Allen, 1880): Deciduous teeth - i ^ , c "p pc ^ Permanent teeth - }• " j- ~ 3 1 1 - 2 - 3 - U - 5 0 - 2 - 3 ' T' . 1 - 2 - 3 - 5 - 5 The eruption of the permanent teeth has not been des-cribed but Scheffer (1958) states that the milk teeth disappear before or soon a f t e r b i r t h . Young harbour seals are weaned at approximately one month of age and probably require a f u l l set of strong teeth for the capture of food. Figure 7 shows the permanent dentition of a young harbour seal. The post canines are double rooted and multilobed, except f o r the f i r s t post canine which i s single rooted. Canines - 3 2 -are large and the outer upper i n c i s o r i s s l i g h t l y enlarged. B. Digestive t r a c t The mouth i s simple and rather elongated i n each species. The tongue Is notched at the t i p , perhaps as an aid i n sucking from a small teat (Scheffer, 1 9 5 8 ) . The esophagus leads d i r e c t l y to the simple "J"-shaped stomach, which i s aligned with the long axis of the body. An unusually long small in t e s t i n e and a r e l a t i v e l y short large intestine i s common to a l l three pinnipeds. The r e l a t i v e shapes and posi-tions of these organs are the same i n each species studied. Several authors have mentioned the great length of the pinniped i n t e s t i n e . Engle ( 1 9 2 6 ) found the whole Intestine of an adult male northern sea l i o n to be about 3 8 times the body length. Laws ( 1 9 5 3 ) found that the in t e s t i n e length i n the southern elephant seal (Mirounga leonlna) varied from twenty to twenty-five times the body length. Mohr ( 1 9 5 2 ) found that the i n t e s t i n e length was 1 3 to 2 2 times the body length of several European pinnipeds. The r a t i o of body length to intestine length was examined i n each of the three pinnipeds under study (Table I I I ) . A l l lengths were taken to the nearest 1 0 cm. Harbour seal and fur seal i n t e s t i n e lengths are approximately the same with a r a t i o of mean body length to mean i n t e s t i n a l length of l : l 6 and 1 : 1 7 , respectively. The range f o r both groups i s 1 : 1 3 to 1 : 2 1 . The sea l i o n body length-intestine length r a t i o i s nearly twice as great at 1 : 3 0 , with a range of 1 : 2 3 to 1 : 3 5 * Table III. Ratio of whole intestine length to body length of fur seals, sea lions and harbour seals. Mean lengths and ratios of means are shown at the bottom of each respective column. Data from animals greater than one year of age. Fur seals Sea lions Harbour seals Body Intestine Ratio Body Intestine Ratio Body Intestine Ratio length length length .length length .length (cm) (cm) (cm) (cm) (cm) (cm) 100 2000 1:20.0 100 1790 1:17.9 150 4500 1:30.0 100 1670 1:16.7 110 1910 1:17.4 160 4760 1:29.7 100 1710 1:17.1 110 1670 1:15.2 160 4430 1:27,6 110 1920 1:17.4 110 1740 1:15.8 180 4170 1:23.2 110 1800 1:16.4 120 2500 1:20.8 180 4960 1:27.5 120 2200 1:18.3 120 2340 1:19.4 180 5000 1:27.8 120 2150 1:17.9 120 1630 1:13.6 190 4840 1:25.5 120 1550 1:12.9 120 1640 1:13.7 190 5450 1:28.6 140 1970 1:14.1 120 2170 1:18.1 210 5900 1:28.1 150 2190 1:14.6 130 1810 1:13.9 220 6260 1:28.5 130 2080 1:16.0 220 6700 1:30.5 130 2240 1:17.2 240 8400 1:35.0 130 2030 1:15.6 250 7080 1:28.3 140 2230 1:15.9 250 7630 1:30.6 260 8320 1:32.0 270 8310 1:29.7 290 9600 1:33.2 300 10130 1:29.7 119 1985 1:17 216 6469 1:30 119 1907 1:16 - 3k -There i s no sa t i s f a c t o r y explanation f o r the r e l a t i v e l y long pinniped i n t e s t i n e or why the northern sea l i o n has an intestine length nearly twice as great, i n r e l a t i o n to i t s body length, as either the harbour seal or f ur seal. The r e l a t i v e l y longer sea l i o n intestine may r e s u l t from the greater volume of t h i s animal. However, the southern elephant seal with a maximum weight of two and one-half tons has a r e l a t i v e l y shorter t r a c t than the northern sea l i o n , with a maximum weight of one ton. Laws ( 1 9 5 3 ) suggested the long pinniped intestine may be an adaptation to diet ; i n p a r t i c u l a r a'mechanism to aid i n the breakdown of the chitinous beaks of molluscs. However, the diet of the three pinnipeds studied here i s quite similar (Figure 1 3 ) , y Q t marked differences are evident i n the body length - i n t e s t i n a l length r a t i o . Further studies to investigate differences at the c e l l u l a r He v e l of the intestine may c l a r i f y t h i s problem. From th i s b r i e f examination two anatomical differences have emerged: the sea l i o n s ' complete permanent dentition i s not evident u n t i l the animal i s eight to nine months of age, and the body length-intestine 3e ngth r a t i o i s approximately 1 : 3 0 . In comparison fur seals and harbour seals, not as closely-related taxonomically as fur seals and sea l i o n s , show si m i l a r -i t i e s i n these two respects: body length-intestine length r a t i o i s approximately 1 : 1 6 i n both cases, and a l l permanent teeth appear before the pups of both species are three months old. Sea l i o n s show the only adjustment i n feeding behaviour - 3 5 -which may be related to the eruption of permanent d e n t i t i o n : sea l i o n pups suckle f o r several months (at le a s t 1 5 months i n some cases) while the fur seal and harbour seal pups are weaned within one to three months afte r b i r t h . FEEDING HABITS A. Comparative feeding behaviour 1 . Capture of prey (a) Fur seals. Most fur seal food consists of small schooling fishes or squids which are eaten beneath the surface. Except f o r very small Items, such as l a n t e r n f i s h , the prey i s usually swallowed head f i r s t (Figure 5 ) « Seals have been observed eating salmon and r o c k f i s h at the surface on four occasions, and a f i s h believed to be a cod once. Larger f i s h such as salmon, cod and r o c k f i s h are brought to the surface, reduced to pieces by violent shaking, and swallowed piecemeal. Fur seals waste l i t t l e of t h e i r prey when feeding. F i s h f l e s h unaccompanied by bones has been observed only twice during the examination of 2 , 0 0 0 stomachs. However, heads of r o c k f i s h may sometimes be discarded; 1 8 out of 2 8 r o c k f i s h ( 6 5 $ ) which had not been affected by digestion, lacked heads. Euphausiids are frequently encountered i n f u r seal stomachs containing herring or r o c k f i s h remains. Data com-paring frequency of occurrence of euphausiids and the stage of digestion of f i s h remains i n the seal stomach indicate that these invertebrates are found only when the f i s h stomach i s exposed by digestion. Such euphausiids had been eaten by f i s h which i n turn were preyed upon by seals. - 36 -T a b l e I V l i s t s t h e maximum numbers o f c e r t a i n f o o d i t e m s f o u n d i n t h e stomachs o f f u r s e a l s . (b) Sea l i o n s . S m a l l f i s h s u c h as h e r r i n g a r e e a t e n u n d e r w a t e r . L a r g e r p r e y a r e b r o u g h t t o t h e s u r f a c e and r e d u c e d t o s m a l l p i e c e s b y v i o l e n t s h a k i n g . On e i g h t o c c a s i o n s s e a l i o n s have b e e n o b s e r v e d e a t i n g l i n g c o d , r o c k f i s h , salmon and h a l i b u t , a t t h e s u r f a c e . S l e p t s o v (1950) r e c o r d s an o b s e r v a t i o n o f a sea l i o n s u r f a c i n g w i t h an o c t o p u s i n i t s jaws. T a b l e IV l i s t s t h e maximum numbers o f c e r t a i n f o o d i t e m s e n c o u n t e r e d i n s e a l i o n s t o m a c h s . ( c ) H a r b o u r s e a l s . An a d u l t s e a l was o b s e r v e d e a t i n g a l a r g e s c u l p i n o r r o c k f i s h a t t h e s u r f a c e on one o c c a -s i o n , w h i l e F i s h e r ( 1 9 5 2 ) o b s e r v e d h a r b o u r s e a l s f e e d i n g on s a l m o n I n t h e Skeena R i v e r . S m a l l s c h o o l i n g f i s h , s u c h as h e r r i n g and e u l a c h o n a r e p r o b a b l y e a t e n b e l o w t h e s u r f a c e , w h i l e l a r g e r p r e y a r e consumed a t t h e s u r f a c e . T a b l e I V l i s t s t h e maximum numbers o f f i s h e n c o u n t e r e d i n h a r b o u r s e a l s t o m a c h s . T a b l e I V . Maximum numbers o f c e r t a i n f o o d i t e m s f o u n d i n i n d i -v i d u a l stomachs o f f u r s e a l s , s e a l i o n s and h a r b o u r s e a l s . F o o d i t e m Maximum numbers of i t e m s f o u n d stomachs i n I n d i v i d u a l F u r s e a l s Sea l i o n s H a r b o u r s e a l s S q u i d 2kk D o g f i s h 3k 7 H e r r i n g 1 8 Salmon 15 7 2 E u l a c h o n 154 iJ+8 Hake 1B W h i t i n g 19 S a b l e f i's'h l l R o c k f i s h 7 15 2 2 - 3 7 -2 . Feeding In r e l a t i o n to hours afte r sunrise Both fur seals and sea l i o n s have less food i n the i r stomachs as the day progresses (Figures 8 and 1 0 ) . Figure 8 i l l u s t r a t e s two samples of fur seal stomachs, one from the Gulf of Alaska and one from B r i t i s h Columbia, r e l a t i n g mean stomach contentjvolume)and hours afte r sunrise. The A l a s k a sample shows c l e a r l y that feeding begins late i n the evening and reaches a peak some time during the hours of darkness. A l l stomachs contained food early In the morning but by 1 1 hours after sunrise a l l stomachs were empty. The B r i t i s h Columbia sample i l l u s t r a t e s the same type of feeding behaviour. Figure 9 shows the corresponding increase i n per cent of empty stomachs as the day progresses f o r the B r i t i s h Columbia sample. Sea l i o n stomach contents show a similar decrease from a mean of 1 , 7 3 2 cc at 1 . 5 hours after sunrise to only 2 cc at 1 5 » 5 hours a f t e r sunrise (Figure 1 0 ) . Figure 1 1 shows the cor-responding increase i n per cent empty stomachs. In comparison with f u r seals and sea l i o n s the harbour seal sample of 5 0 stomachs indicates daylight feeding (Figure 1 2 ) . Samples have not been collected during the hours of darkness. This includes a period of four hours f o r fur seals, eight hours for sea li o n s and 1 2 hours f o r harbour seals. No conclusions can be reached regarding feeding habits of harbour seals during the hours of darkness; feeding may or may not occur. However, f u r seals and sea l i o n s feed mainly during the hours of darkness and the early morning. Stomachs collected during the morning contain food and mean volumes are high. - 3 8 -These contents are digested throughout the day and by early evening stomachs are empty. B. Daily food consumption In order to f i n d out the e f f e c t of pinniped predation upon commercially valuable f i s h stocks, an estimation of d a i l y food requirements must be made. Table V indicates that p i n n i -ped food requirements range from two to eleven per cent of body weight, with an average d a i l y food intake of s i x per cent of the animals' body weight. Refinement of these data to allow f o r growth, pregnancy, l a c t a t i o n or hard work (for long migrations) i s impossible; detailed studies of the n u t r i t i o n a l requirements of pinnipeds have not been undertaken. C. Comparison of food items eaten Pood items i d e n t i f i e d i n the stomachs of each of the three pinniped species under investigation have been sum-marized i n Figure 1 3 , regardless of date or loc a t i o n of c o l -l e c t i o n . Items which occurred only once i n the sample are not included. This figure has been arranged i n such a manner as to point out s i m i l a r i t i e s and differences which exi s t between each of the predators studied: food items common to a l l three are shown f i r s t and items common to two or only one follow. The factors which prevent extensive intermingling of the northern fur seal, sea l i o n and the harbour seal do not r e s t r i c t movements of t h e i r prey. Ten of the 2 1 food Items i n Figure 1 3 , squid, clupeids, salmon, rockfish, cod, hake, f l a t f i s h , greenling, lamprey and smelts are common to a l l three pinnipeds; combined they contribute over 5 0 $ to the diet - 39 -Table V. Daily food consumption of pinnipeds as reported i n the literature, plus the maximum weights of stomach contents from individual animals collected in the f i e l d . Species of seal Authority Body weight (lb) Food intake (lb/day) Daily food intake as a percentage of body weight Northern fur seal Scheffer (1958) Anon. (1962) . Sergeant (1962) 66 65 4 4 7 6 5 Observed maximum 106 11 10 Northern sea lio n Scheffer (1958) 600 14 2 Observed maximum 490 1500 19 35 4 2 Harbour seal Havinga (1933) Scheffer.(1958) 66 70 3 4 5 6 Observed maximum 62 7 11 Gray seal Myers (1955) 150 10 7 Mean 6 - 40 -6 2 . Lo S 10 Id. !¥• /£> 16 Hours a f t e r s u n r i s e F i g ure 8. Fur s e a l stomach volumes and hours a f t e r s u n r i s e . Figure 9. Per cent empty stomachs and hours a f t e r s u n r i s e ( f u r s e a l s ) . - 42 -IS J-5" J J 7-5" 9'5~ IIS 13? /5-5 Hours a f t e r s u n r i s e F i g u r e 10. Mean stomach volume of 269 sea l i o n s and hours a f t e r s u n r i s e . - € 3 -Figure 11>: Percent empty stomachs and hours a f t e r s u n r i s e -sea l i o n s , 269 stomachs, 130 empty. llOOr IO0O aoo-ioDO 400 loo-O I = I * I s • : I : I • I 2 H- 6 & IO 12. Hours of su n r i s e F i g u r e 12. Mean stomach volumes and hours a f t e r s u n r i s e i n a sample of 50 harbour s e a l s . - 45 -F i g u r e 13. Stomach contents of f u r s e a l s , sea l i o n s , harbour s e a l s , c o l l e c t e d along the coast of B r i t i s h Columbia. of each predator. The differences which do exist, however, may be explained l a r g e l y by differences i n d i s t r i b u t i o n of each group of predator. Most fur seals are offshore (Table II) and th e i r d i e t consists l a r g e l y of small f i s h and squid schooling at the surface. Sea l i o n s and harbour seals are inshore (Table I I ) ; bottom f i s h and octopus are more important In t h e i r d i e t . The high percentage of salmon i n the harbour seal sample i s due to 2.9 stomachs collected i n the v i c i n i t y of salmon spawning creeks during September and October, 1961; t h i s Is not repre-sentative of the actual role of salmon i n the yearly diet of these seals. D. Unusual stomach contents Small pebbles, sand, b i t s of wood or bark, kelp and small clam she l l s have occasionally been found i n stomachs of each of the three groups studied. I t i s believed these are ingested accidently. However, smooth stones of varying shapes from one-half Inch to three inches across, are found so f r e -quently i n sea l i o n stomachs that some functional explanation Is Indicated. Oneto ten stones weighing up to four pounds were found i n one-third of a l l sea l i o n stomachs examined. Several suggestions have been presented i n an attempt to explain the presence of stones i n pinniped stomachs: (a) stones are taken accidentally when sea l i o n s prey on octopuses which have stones grasped i n t h e i r tentacles (Sleptsov, 1950); (b) they add bulk to the stomach during periods of f a s t i n g (Howell, 1930, and Laws, 1956); (c) they aid i n div i n g (Murray and Renard i n Emery, 19I4.I, and Hamilton, 1933); (d) they -kl -macerate stomach parasites (Hamilton,, 1 9 3 3)> (e) they aid i n the ph y s i c a l breakdown of food i n the stomach (Mathews, 1 9 2 9 ) . Two observations do not support the theory that stones are ingested accidentally with octopus remains: (a) stones were found i n the stomach of a six-month-old nursing sea l i o n ; apparently even young animals are capable of picking up and swallowing such objects; (b) stones are not found i n the stomachs of harbour seals which frequently prey upon octopus. Although Laws ( 1 9 5 6 ) presented convincing evidence to support his theory that stones add bulk to the stomach of a f a s t i n g elephant seal, his theory does not apply to the stones found i n northern sea l i o n stomachs. These are found throughout the year and i n the stomachs of l a c t a t i n g cows, when n u t r i t i o n a l requirements are high. Mathews' ( 1 9 2 9 ) theory that stones aid i n the break-down of food i s supported by evidence from the northern sea l i o n . The sea l i o n teeth, p a r t i c u l a r l y the post canines, are designed f o r grasping and tearing rather than grinding (Figure 6 ) ; thus, food i s swallowed i n pieces. As much of the sea l i o n food consists of large, heavily-boned species the grinding a c t i v i t y of stones i n the stomach would be of great assistance i n the physical maceration of f l e s h , bones and octopus beaks. Observations of captive animals have shown that such stones are e a s i l y regurgitated, and t h i s occurs after the digestion of food (Emery, 1 9 1 + 1 ) . Stones si m i l a r to those found i n sea l i o n stomachs are also found on sea l i o n haul-out rocks. The majority of the f u r seals' food, and probably that of the harbour seal, i s smaller f i s h or squid; an addi t i o n a l - 1+8 -grinding mechanism i n the stomach i s not needed. E. Comparative seasonal feeding habits Differences i n feeding habits of these three pinnipeds are evident, r e l a t i n g to time of year and also to area. Accord-ingly, the samples have been grouped as to season and area of c o l l e c t i o n . The feeding habits of f u r seals during January, February, March, A p r i l and May are described i n d e t a i l (Table VI); whenever possible comparisons have been made with the feeding habits of sea l i o n s and harbour seals (Table V i i ) . Following the northward migration of f ur seals, sea lio n s and harbour seals remain. The samples from these two species have been divided into "summer breeding" and "summer non-breeding" categories f o r sea l i o n s , and a "summer" sample for harbour seals. Samples from September 15> to December 3 0 have also been combined. The B r i t i s h Columbia coast has been divided into four main areas (Figure ll+) as an aid to describing feeding habits. This figure also shows the major sea l i o n and harbour seal l o c a l i t i e s mentioned i n the text. Area I extends from 1+8°0G'N to 5l°00'N or the north end of Vancouver Island; area II includes waters off the west coast of the Queen Charlotte Islands; area I II includes Hecate S t r a i t , Queen Charlotte S t r a i t and Dixon Entrance; while area IV includes a l l protected channels and i n l e t s of the B r i t i s h Columbia coast. References to numbers of stomachs i n the following account refer to numbers of stomachs with food only. F i g u r e 14. C o l l e c t i n g areas on the B r i t i s h Columbia coast (Area IV i n c l u d e s a l l protected i n l e t s and channels). I'iiHLi VI: Fur seal stomach contents by month and area. Source of data as in Table I. MONTH JAN. FEBRUARY MARCH APRIL MAI JUKE- TOTALS AREA IV I III IV I III IV I III IV I IV I II III IV Stomachs vtdth food. Stomachs empty. 8 9 1 22 19 15 11 69 118 20 16 46 39 334 495 9 16 6 1 324 413 2 1 43 53 9 7 3 1 1 1 912 l^OO 1 TOTALS 17 1 41 26 187 36 85 829 25 7 737 3 96 16 4 2 2.1A2 SPECIES Lolieo op. G. maeister Unid. Squid Lamprey Ratfish Herring Shad Clupeids Anchovy Salmon Eulachon Capelin Smelt Saury Hake Whiting Cods King- of-the-s Fl a t f i s h Greenling -Pomfret Squaretail Sablefish Rockfish Stickleback Sandlance Birds Misc.4 Unid. Fish4 F2 F F F F F % F % F % F F 1 F % F F F F F F 6 1 -Oman 2 1 2 1 4 7 2 1 1 9 1 3 3 1 1 ' 2 1 3 1 1 4 3 19 3 24 2 3 6 2 1 1 2 4 6 11 22 3.4 21.9 3.4 27.6 2.3 3.4 6.9 2.3 1.2 1.2 2.3 4.6 6.9 12.6 2 4 8 1 7 1 1 7 1 2 3 6.2 12.5 25.0 3.1 21.9 3.1 3.1 21.9 3.1 28 58.3 11 22.S 4 8.3 2 4.2 1 2.1 1 2.1 1 2.1 1 4 2 44 1 180 19 4 14 30 1 6 6 1 1 2 1 18 28 25 18 2 9 60 0.5 10.9 0.2 44.8 4.7 1.0 3.5 7.5 0.2 1.5 1.5 0.2 0.2 0.5 0.2 4.5 7.0 6.2 4.5 0.5 2 6 1 2 4 5 2 5 44 1 1 188 3 4 34 5 1 7 4 3 1 4 3 1 1 12 7 2 7 1 8 93 1.5 13.1 0.2 0.2 56.0 0.9 1.2 10.1 1.5 0.2 2.1 1.2 0.9 0.2 1.2 0.9 0.2 0.2 3.6 2.1 0.6 2.1 0.2 1 1 1 6 28 2 4 5 3 1 3 1 1 11.1 51.9 3.7 7.4 9.3 5.6 1.8 5.6 1.8 1.8 9 1 1 1 1 1 4 1 1 2 1 13 28 158 6 6 443 24 5 9 59 48 1 10 15 12 16 6 9 7 46 41 39 26 9 TOTALS 9 14 16 87 100.0 32 99.9 48 100.0 403 100.1 11 7 339 100.1s 2 54 100.0 14 2 1 1,036 1 - one empty stomach collected i n area 4 during May not included 2 - frequency of occurrence 3 - per cent frequency of occurrence 4 - not used i n calculations T A B L ^ V I I '• Harbour s e u l and sea lion stomach contents, by month and area. Source of data as in Table I . SEA LIONS HARBOUR SiiAL WINTER SUMMER FALL WINTER SUMMER FALL MONTH Dec. Feb. Mar. Apr. May 15-Sept. 15 May 15-Sept. 15 Sept. 16 -Dec. 15 Jan, Feb. Mar. Apr. May May 15-Sept. 15 Sept. 16 -Dec. 15 AREA IV IV IV IV Breeding Colonies Non-Breeding Colonies Entire Coast IV IV IV IV IV IV IV Stomachs with food. 3 9 2 92 35 35 1 1 2 1 0 26 38 Stomachs empty. 0 2 5 2 155 22 17 0 1 1 0 1 48 6 TOTALS 14 5 14 4 247 57 52 1 2 3 1 1 74 44 SPECIES F l F - F F F *2 F it F % F F F F F F % F % Shrimp 2 2.4 1 2.4 2 Clamshell 2 3 3.5 1 2.4 1 2.4 2 6.5 1 2.2 Octopus 1 1 1 36 42.4 5 12.2 1 2.4 8 25.8 7 15.2 Squid 1 5 5.9 2 4.9 3 7.1 1 3.2 8 17.4 Lamprey 1 1.2 2 6.5 Skate 1 Batfish 2 2.4 2 4.9 1 2.4 Dogfish 1 1 1 5 5.9 2 4.9 3 7.1 Herring 12 1 3 1 1.2 1 2.4 1 3 9.7 5 10.8 Salmon 6 7.1 4 9.5 5 16.1 14 30.4 Eulachon 1 2 Smelt 1 1 2.2 Hake 3 3.5 8 19.0 1 Graycod 1 2.4 1 2.4 Whiting 1 2 3 3.5 9 21.9 3 7.1 1 2.2 Halibut 1 2.4 Flatfish 4 9.8 3 7.1 4 8.7 Seaperch 1 2.2 Mackereljack 1 2.4 Sablefish 1 3.2 1 2.2 Lingcod 1 1 2.4 1 3.2 Greenling 1 2.2 Rockfish 2 1 11 12.9 9 21.9 7 16.7 7 22.6 1 2.2 Cabezon 1 2.2 Sandlance 1 1.2 2 4.9 Sea bird 1 3.2 Milk 1 6 7.1 2 4.9 4 9.5 Kelp3 1 1 Unidentified^ 2 25 3 4 1 19 6 TOTALS 17 3 11 4 85 100.0 41 99.9 42 99.9 1 2 2 1 0 33 100.0 46 100.1 1 - frequency of occurrence 2 - per cent frequency of occurrence 3 - not used in calculations - 52 -1. W i n t e r - s p r i n g (a) J a n u a r y . P u r s e a l s f i r s t a p p e a r i n J a n u a r y and a r e t o be f o u n d i n H e c a t e S t r a i t , Queen C h a r l o t t e Sound and some o f t h e n o r t h e r n i n l e t s . T hese a r e m o s t l y y o ung males and f e m a l e s , b u t some a d u l t cows a r e a l s o s e e n a t t h i s t i m e . E i g h t f u r s e a l stomachs were c o l l e c t e d d u r i n g J a n u a r y i n K n i g h t I n l e t and Queen C h a r l o t t e S t r a i t . S q u i d and s m a l l s a b l e f i s h were t h e most i m p o r t a n t f o o d s p e c i e s i d e n t i f i e d . Male sea l i o n s , p l u s a few n o n - l a c t a t i n g cows and immature f e m a l e s a r e t o be f o u n d on h a u l - o u t r o c k s a d j a c e n t t o t h e c o a s t , o r i n more p r o t e c t e d w a t e r s f o l l o w i n g h e r r i n g ; most cows w i t h pups a r e on t h e r o o k e r i e s . T h e r e a r e no sea l i o n s tomachs a v a i l a b l e f o r t h i s month. H a r b o u r s e a l s may be f o u n d anywhere a l o n g t h e c o a s t . One h a r b o u r s e a l , c o l l e c t e d i n K n i g h t I n l e t d u r i n g J a n u a r y , had b e e n f e e d i n g on e u l a c h o n . (b) F e b r u a r y . D i s t r i b u t i o n o f a l l s p e c i e s i s q u i t e s i m i l a r t o t h a t o f J a n u a r y , a l t h o u g h more y o u n g f u r s e a l s a r e e v i d e n t i n a l l n o r t h e r n a r e a s and some a d u l t and young f u r s e a l s m a y . a l s o be f o u n d o f f t h e west c o a s t o f V a n c o u v e r I s l a n d . Stomach c o n t e n t s f r o m 22 f u r s e a l s c o l l e c t e d i n H e c a t e S t r a i t i n d i c a t e t h a t h e r r i n g was t h e p r i m a r y i t e m i n t h e d i e t w h i l e w h i t i n g and s q u i d were o f s e c o n d a r y i m p o r t a n c e . F u r s e a l s f r o m i n s i d e w a t e r s were f e e d i n g m a i n l y on s m a l l s a b l e f i s h , r a t f i s h and s q u i d w h i c h f o r m e d o v e r h a l f t h e d i e t . T h r e e sea l i o n s , c o l l e c t e d f r o m B e r k l e y Sound and S a a n i c h I n l e t a t t h i s t i m e o f y e a r had been f e e d i n g on w h i t i n g , h e r r i n g and d o g f i s h . - 53 -One h a r b o u r s e a l c o l l e c t e d i n B a r k l e y Sound d u r i n g F e b r u a r y had been f e e d i n g on hake. (c) March. By l a t e March the young f u r s e a l s b e g i n t o l e a v e the p r o t e c t e d waters of B r i t i s h Columbia's c o a s t , w h i l e t h e r e i s an i n c r e a s e i n the number of a d u l t f u r s e a l s a p p e a r i n g o f f Vancouver I s l a n d . One hundred and t h i r t y - f i v e f u r s e a l stomachs were c o l l e c t e d d u r i n g March i n areas I , I I and IV. Twenty stomachs from Hecate S t r a i t i n d i c a t e d t h a t h e r r i n g was the most pre-, f e r r e d f i s h , w h i l e s q u i d , w h i t i n g and s m a l l s a b l e f i s h were a l s o i m p o r t a n t . A sample of 69 stomachs from area I i n d i c a t e d t h a t h e r r i n g and s q u i d were the two most i m p o r t a n t items con-t r i b u t i n g 50$ t o the d i e t . F u r s e a l s from i n s i d e w a t e r s , p r e -d o m i n a t e l y y e a r l i n g s c o l l e c t e d i n K n i g h t I n l e t , were p r e y i n g h e a v i l y upon the s q u i d , Gonatus m a g i s t e r . Q u a n t i t a t i v e data on the movement of sea l i o n s i n B a r k l e y Sound i n d i c a t e t h a t sea l i o n s r e a c h t h e i r maximum numbers i n March, presumably f o l l o w i n g the h e r r i n g . Sea l i o n s move i n t o K n i g h t I n l e t d u r i n g March and A p r i l . Nine sea l i o n stomachs were c o l l e c t e d i n K n i g h t I n l e t and Queen C h a r l o t t e S t r a i t d u r i n g March. W h i t i n g , h e r r i n g and r o c k f i s h o c c u r r e d seven times i n a t o t a l of e l e v e n i d e n -t i f i a b l e f o o d s . The h a r b o u r s e a l s c o l l e c t e d i n K n i g h t I n l e t d u r i n g March had been f e e d i n g on e u l a c h o n . (d) A p r i l . D u r i n g A p r i l the main n o r t h w a r d - m i g r a t i n g f u r s e a l h e r d has reached s o u t h e r n B r i t i s h Columbia w a t e r s , w h i l e most of the young f u r s e a l s have moved out of the s h e l t e r e d - Bk -i n s i d e w a t e r s . T h r e e h u n d r e d and f o r t y - n i n e f u r s e a l stomachs were c o l l e c t e d i n a r e a s I , I I I and IV. H e r r i n g p r e d o m i n a t e d i n t h e n i n e stomachs c o l l e c t e d i n H e c a t e S t r a i t . A l a r g e sample o f 33I4. stomachs f r o m s o u t h e r n V a n c o u v e r I s l a n d i n d i c a t e d t h a t h e r r i n g was a g a i n t h e most i m p o r t a n t f o o d s p e c i e s , b u t s q u i d , s had, s t i c k l e b a c k , e u l a c h o n and r o c k f i s h were a l s o t a k e n f r e -q u e n t l y . S q u i d p r e d o m i n a t e d i n stomachs o f s i x y o u n g a n i m a l s c o l l e c t e d f r o m a r e a IV. Sea l i o n s w h i c h , p r i o r t o A p r i l , had s c a t t e r e d t h r o u g h o u t many o f t h e i n l e t s and i n s i d e p a s s a g e s p r o b a b l y b e g i n t h e i r m i g r a t i o n b a c k t o t h e r o o k e r i e s by t h e end o f A p r i l . Two s e a l i o n stomachs were c o l l e c t e d d u r i n g A p r i l i n B a r k l e y Sound and K n i g h t I n l e t ; t h e f o r m e r had been f e e d i n g on r o c k -f i s h , o c t o p u s and s k a t e , w h i l e t h e l a t t e r had b e e n f e e d i n g on e u l a c h o n . H a r b o u r s e a l s a r e d i s t r i b u t e d o v e r t h e e n t i r e c o a s t , w i t h no e v i d e n c e o f h e r d i n g . One h a r b o u r s e a l c o l l e c t e d o f f Maude I s l a n d , S t r a i t o f G e o r g i a , i n A p r i l , had been f e e d i n g on h e r r i n g . ( c ) May. D u r i n g t h e e a r l y p a r t o f May, v i r t u a l l y a l l f u r s e a l s have l e f t H e c a t e S t r a i t and a r e a I V w a t e r s , w h i l e f u r s e a l s o f a l l ages a r e abu n d a n t o f f V a n c o u v e r I s l a n d . By t h e end of May t h e a d u l t s h a v e p a s s e d i n t o A l a s k a n w a t e r s . T h r e e h u n d r e d and t w e n t y - s i x f u r s e a l stomachs f r o m a r e a s I , I I I and I V c o n t a i n e d f o o d d u r i n g May. A l a r g e sample o f 32I+ stomachs c o l l e c t e d i n a r e a I i n d i c a t e d t h a t h e r r i n g a g a i n c o m p r i s e d o v e r h a l f t h e f o o d . Salmon assumed i t s g r e a t e s t - 55 -i m p o r t a n c e d u r i n g May i n t h e f u r s e a l d i e t i n t h i s a r e a when i i t c o n t r i b u t e d 10.1$ t o t h e t o t a l i n t a k e o f f o o d . The t h r e e s p e c i e s , k i n g - o f - t h e - s a l m o n , p o m f r e t and s q u a r e t a i l , were e n c o u n t e r e d i n one s t o m a c h c o l l e c t e d 200 m i l e s s o u t h w e s t of E s t e v a n P o i n t , V a n c o u v e r I s l a n d . A l l sea l i o n and h a r b o u r s e a l s p e c i m e n s were c o l l e c t e d l a t e r t h a n May 15 and have t h e r e f o r e been p l a c e d i n t h e a p p r o -p r i a t e "summer" c a t e g o r y b e l o w . 2. Summer (a) F u r s e a l s . D u r i n g J u n e t h e r e a r e s t i l l a few l a t e m i g r a n t s , m o s t l y y o u n g a n i m a l s o f f B r i t i s h C o l u m b i a . F o r t y - s e v e n - s e a l s f r o m t h e west c o a s t o f V a n c o u v e r I s l a n d had been f e e d i n g on h e r r i n g , h a k e , cod and s q u i d . O n l y n i n e f u r s e a l s tomachs have b e e n c o l l e c t e d f r o m w a t e r s west o f t h e Queen C h a r l o t t e I s l a n d s . These s e a l s , c o l l e c t e d d u r i n g J u n e b e t w e e n 100-150 m i l e s o f f s h o r e , were f e e d i n g m a i n l y on an u n i d e n t i f i e d s q u i d ( n i n e out o f a t o t a l o f f o u r t e e n o c c u r r e n c e s ) , w h i l e s a u r y , r a t f i s h , w h i t i n g and l a m p r e y r e m a i n s were a l s o i d e n t i f i e d . One o f t h e s e n i n e s t o m a c h s , c o l l e c t e d a t 5^°21 ' N -136°2li'W, c o n t a i n e d l a m p r e y , w h i t i n g and r a t f i s h w h i c h i s t y p i c a l o f an i n s h o r e s t o m a c h . A m i s t a k e may have b e e n made i n p o s i t i o n i n g t h i s s e a l ; i f t h i s was the case s q u i d has an even g r e a t e r I m p o r t a n c e i n t h i s sample t h a n i s shown i n T a b l e V I . (b) Sea l i o n s . By l a t e May and e a r l y J u n e 70$ o f t h e sea l i o n p o p u l a t i o n have c o n g r e g a t e d on t h e r o o k e r i e s o f Cape S t . James and t h e S c o t t I s l a n d s , f u r p u p p i n g and b r e e d i n g . O c t o p u s , f o r m i n g n e a r l y h a l f of t h e c o n t e n t s e x a m i n e d , i s b y f a r t h e most i m p o r t a n t f o o d , a l t h o u g h r o c k f i s h , d o g f i s h and - 56 -s a l m o n were a l s o p r e y e d upon q u i t e h e a v i l y . S i x y e a r l i n g s tomachs c o n t a i n e d m i l k . The sample f r o m n o n - b r e e d i n g , o r h a u l - o u t , r o c k s i n d i c a t e s t h a t o c t o p u s i s o f l e s s i m p o r t a n c e w h i l e w h i t i n g and r o c k f i s h a r e t h e two m a j o r f o o d i t e m s . ( c ) H a r b o u r s e a l s . By J u n e , a c c o r d i n g t o D. McNaughton ( p e r s o n a l c o m m u n i c a t i o n ) , many h a r b o u r s e a l s have c o n g r e g a t e d i n t o s m a l l h e r d s i n i s o l a t e d a r e a s a l o n g t h e c o a s t l i n e where p u p p i n g o c c u r s . Many o f t h e s e h e r d s a p p a r e n t l y r e m a i n t o g e t h e r u n t i l t h e end of t h e summer. However, i n some a r e a s , e.g., t h e Skeena R i v e r , s e a l h e r d s b r e a k up f o l l o w i n g t h e p u p p i n g p e r i o d and t h e . a n i m a l s move e i t h e r down o r up r i v e r by t h e end o f J u n e ( F i s h e r , 1952). T w e n t y - s i x stomachs a r e a v a i l a b l e f o r t h e summer months, c o l l e c t e d m o s t l y f r o m t h e F r a s e r and Skeena R i v e r s . I n t h i s sample o c t o p u s , r o c k f i s h , s a l m on and h e r r i n g a r e t h e most i m p o r t a n t f o o d I t e m s . 3. F a l l T h e r e a r e no f u r s e a l stomachs a v a i l a b l e f o r t h e f o u r months f r o m September t o December. T h i s s p e c i e s I s r a r e l y f o u n d i n B r i t i s h C o l u m b i a w a t e r s u n t i l J a n u a r y (Manzer and Cowan, 1956). ( a ) Sea l i o n s . D u r i n g t h e e a r l y f a l l many s e a l i o n s b e g i n t o l e a v e t h e b r e e d i n g r o c k s and s c a t t e r a l o n g t h e c o a s t l i n e . M a l e s , and f e m a l e s w i t h o u t p u p s , p r o b a b l y move s o u t h f r o m t h e S c o t t I s l a n d s t o w a r d s V a n c o u v e r I s l a n d o r t o w a r d s t h e m a i n l a n d I n l e t s . Sea l i o n s on Cape S t . James p r o b a b l y move n o r t h w a r d s up b o t h t h e e a s t and west c o a s t s o f - 57 -t h e Queen C h a r l o t t e I s l a n d s , o r a c r o s s H e c a t e S t r a i t t o t h e m a i n l a n d . The sample o f 35 stomachs f r o m S c o t t I s l a n d s , Cape S t . James, i n s i d e w a t e r s o f Moresby I s l a n d , Skedans and I s n o r R o c k s , i n d i c a t e s t h a t a t t h i s t i m e o f y e a r r o c k f i s h and hake a r e t h e most i m p o r t a n t f o o d s p e c i e s . Salmon i s t h e t h i r d most p r e v a l e n t f o o d and i s t a k e n l a r g e l y by s e a l i o n s w h i c h have moved i n t o t h e I n l e t s and c r e e k mouths where s a l m o n a r e r e a d i l y a v a i l a b l e . F i v e m a c k e r e l j a c k , t o t a l l i n g 18 p o u n d s , were i d e n -t i f i e d i n one s t o m a c h c o l l e c t e d f r o m t h e S c o t t I s l a n d s d u r i n g September, 196l . T h i s s p e c i e s i s f a i r l y common d u r i n g t h e summer months i n w a t e r s o f f t h e B r i t i s h C o l u m b i a c o a s t (Clemens and W i l b y , 1961). M i l k was i d e n t i f i e d f r o m f o u r lli - 1 5-month-o l d a n i m a l s c o l l e c t e d d u r i n g t h e f a l l . ( b) H a r b o u r s e a l s . D u r i n g t h e e a r l y f a l l t h e s m a l l h e r d s o f h a r b o u r s e a l s a p p a r e n t l y b r e a k up and a l l members d i s p e r s e . I t i s b e l i e v e d t h e s e movements a r e r e l a t i v e l y l i m i t e d a l t h o u g h t h e y have n o t b e e n s t u d i e d c l o s e l y . The i i l i stomachs a v a i l a b l e f o r t h i s p e r i o d a r e p r e -d o m i n a t e l y f r o m t h e Queen C h a r l o t t e I s l a n d s , c o l l e c t e d when salmon were m o v i n g i n t o t h e s t r e a m s t o spawn; c o l l e c t i o n s were a l s o made on t h e S c o t t I s l a n d s and i n t h e G u l f o f G e o r g i a . Salmon was t h e most i m p o r t a n t f o o d i t e m ( m o s t l y chum and p i n k s almon) c o n t r i b u t i n g 30.1i$ t o t h e d i e t ( T a b l e V I I ) . O c t o p u s and s q u i d were f r e q u e n t l y e a t e n -The s e a s o n a l f o o d h a b i t s o f t h e s e t h r e e p i n n i p e d s may be summarized as f o l l o w s : i ) F u r s e a l s : H e r r i n g i s t h e most i m p o r t a n t f o o d d u r i n g a l l months o f f V a n c o u v e r I s l a n d and i n H e c a t e S t r a i t , w h i l e s q u i d a r e a l s o t a k e n f r e q u e n t l y . Salmon assumes i m p o r t a n c e - 58 -only during May off Vancouver Island. Seals i n inside waters feed mainly on squid, r a t f i s h and sa b l e f i s h . i i ) Sea l i o n s : Rockfish are one of the main food items f o r a l l sea l i o n s at a l l times of the year. In addition to ro c k f i s h , herring are important during the winter; octopus, dogfish and salmon are taken frequently by breeding animals, while non-breeding animals feed heavily on whiting during the summer. Rockfish, salmon, whiting and hake are important food items during the f a l l . I i i ) Harbour seals: During the winter eulachon i s an important food, p a r t i c u l a r l y i n the i n l e t s . Summer sampling, mostly on the Skeena and Fraser Rivers, Indicated that octopus, r o c k f i s h and salmon were the important food Items. During the f a l l , salmon constitutes nearly one-third of the food eaten. F. Predator-prey size relationships Prey size may have an important bearing upon the f i s h species preferred by each respective predator and two aspects of t h i s problem haverbeen investigated: (a) di f f e r e n t feeding habits between sea lio n s and fur seals produced by i n t e r - s p e c i -f i c size differences; (b) an increase i n prey size with the increasing age (and size) of fur seals. 1. Inter-specif1c differences Table VIII compares the importance of large and small food items i n the diet of f u r seals and sea l i o n s . The mean fur seal weight was only 29.1 kg with a range of 5*9-63.5 kg, while the mean female sea l i o n weight was 177 kg with a range of 58-265 kg. Although no mature b u l l sea l i o n weights were - 59 -t a k e n , some b u l l s w e i g h 90° k g (Cowan and G-uiguet, 1956). P r o f e s s i o n a l b u t c h e r s have e s t i m a t e d t h a t l a r g e b u l l s t a k e n f o r mink f o o d w e i g h 680 k g (1500 l b ) . T h i s t a b l e i l l u s t r a t e s t h e i m p o r t a n c e o f s m a l l s c h o o l i n g f i s h e s i n t h e f u r s e a l s ' d i e t : 63$ compared t o 11$ i n t h e s e a l i o n s ' d i e t . I n c o m p a r i s o n , t h e l a r g e s p e c i e s o f salmon, r o c k -f i s h , d o g f i s h , c o d , h a k e , h a l i b u t and l i n g c o d c o m p r i s e \yfo o f t h e s e a l i o n s ' f o o d b u t o n l y 12$ o f t h e f u r s e a l s ' f o o d . As 75$ o f t h e h a r b o u r s e a l stomachs were c o l l e c t e d i n t h e v i c i n i t y o f s a l m o n s t r e a m s and r i v e r s t h e y c a n n o t be a n a l y s e d i n t h e above manner. 2. I n t r a - s p e c i f i c d i f f e r e n c e s ( f u r s e a l s ) T a b l e IX and F i g u r e 15 summarize t h e a v a i l a b l e d a t a on f e e d i n g b e h a v i o u r o f f u r s e a l s , a c c o r d i n g t o age. U n i d e n -t i f i e d c o n t e n t s and s p e c i e s w h i c h o c c u r r e d o n l y r a r e l y have n o t b e e n i n c l u d e d . W i t h i n c r e a s i n g age, and t h u s s i z e o f p r e d a t o r , f i s h o f l a r g e r s i z e ( s a l m o n , cod, hake, r o c k f i s h and s h a d ) become i n c r e a s i n g l y i m p o r t a n t : a r i s e o c c u r s f r o m t h r e e p e r c e n t f r e -q u e n c y o f o c c u r r e n c e i n t h e one y e a r age group t o 38$ and 37$ r e s p e c t i v e l y , i n t h e n i n e t o t e n and 10T age g r o u p s . Shad e a t e n b y f u r s e a l s a r e l a r g e r t h a n o t h e r c l u p e i d s p e c i e s and have t h e r e f o r e b e e n g r o u p e d w i t h t h e l a r g e r f o o d i t e m s . W i t h i n c r e a s i n g age o f f u r s e a l s , f o o d s o t h e r t h a n t h o s e l a r g e r s p e c i e s m e n t i o n e d above a r e of d e c r e a s i n g i m p o r t a n c e i n t h e d i e t . T h ese c o m p a r i s o n s show t h a t p r e d a t o r s i z e has a d i r e c t b e a r i n g upon p r e y s i z e . L a r g e f u r s e a l s p r e y on l a r g e r f o o d i t e m s t h a n s m a l l f u r s e a l s ; sea l i o n s p r e y on l a r g e r f o o d i t e m s Figure ."15: A n a l y s i s of 699 f u r s e a l stomachs c o n t a i n i n g food, showing s e l e c t i v e food preferences according to age. - 61 -Table V I I I . Comparison of large and small food items eaten by fur seals and sea lions. Frequency expressed as a percentage of total occurrences of a l l food items from Table V i . Prey (large) Salmon Rockfish Cod Dogfish Hake Halibut Lingcod Mackereljack Sub total Total occurrences ( a l l species) Per cent Sea lions p* Predators Fur seals P 10 59 30 41 20 22 13 11 12 1 2 1 88 203 43.4 134 1036 11.9 Prey (small) Clupeids Smelt Sablefish (small) Stickleback Sandlance Sub total Total occurrences ( a l l species) Per cent 18 1 481 59 46 39 26 22 203 10.8 651 1036 62.8 •Frequency of occurrence - 62 -Table IX. Analysis of 699 fur seal stomachs containing food showing selec-tive feeding behaviour according to age. (Data from present investigation only.) Food items Age (years) 1 2 3-4 5-6 7-8 9-10 10+ Totals Clupeids*and smelt F^ 77 38 45 59 35 18 49 301 % 3 37.0 52.0 50.0 44.3 37.6 36.0 41.5 Salmon, cod, rockfish, hake and shad F 7 2 IS.'.' 25 28 19 44 140 % 3.4 2.7 16.7 28.4 30.1 38.0 37.3 Squid F 89 16 15 13 15 8 13 169 % 42.8 21.9 16.7 14.8 16.1 16.0 11.0 Sablefish, saury, stickleback and sandlance F 35 17 15 11 15 5 12 110 % 16.8 23.3 16.7 12.5 16.1 10.0 10.2 Totals F 208 73 90 88 93 50 118 720 % 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Total food Total empty 196 77 98 79 90 48 111 699 261 115 140 80 75 41 65 777 Clupeids do not include shad. Frequency of occurrence. 'Per cent frequency of occurrence. - 63 -t h a n t h e s m a l l e r f u r s e a l s . G. F e e d i n g h a b i t s and r e p r o d u c t i o n P i n n i p e d f o o d h a b i t s d u r i n g t h e p u p p i n g and b r e e d i n g s e a s o n were examined p r i m a r i l y t o d e t e r m i n e th e p e r i o d o f r e d u c e d f o o d i n t a k e . 1. F u r s e a l s A v a i l a b l e d a t a i n d i c a t e t h a t f o o d i n t a k e by t h e m a l e s i s r e d u c e d . A b e g g l o n et_ _al (1958) r e p o r t t h a t " o n l y 27 stomachs c o n t a i n e d f o o d among the t h o u s a n d s o f empty ones, i n t h e S t . P a u l I s l a n d f u r s e a l h a r v e s t " . B a r t h o l o m e w and H o e l (1953) c o n -c l u d e d t h a t harem m a s t e r s d i d n o t f e e d f o r t h e two months o f J u n e and J u l y w h i l e t h e y m a i n t a i n e d t h e i r t e r r i t o r i e s . S t u d i e s c a r r i e d out d u r i n g t h e p r e s e n t f u r s e a l r e s e a r c h p r o g r a m have i n d i c a t e d , however, t h a t t h i s t y p e o f b e h a v i o u r does n o t a l w a y s o c c u r (Anon, 196l). R u s s i a n i n v e s t i g a t o r s have shown t h a t harem b u l l s on t h e Commander and Robben I s l a n d s r e m a i n on t h e i r t e r r i -t o r i e s f o r l e s s t h a n one month a t any one t i m e , and t h a t v a c a n c i e s on t h e r o o k e r i e s a r e f i l l e d by r e s e r v e b u l l s . The cows come a s h o r e , and w i t h i n t h r e e d a y s g i v e b i r t h t o t h e i r pups (Bartholomew and H o e l , 1953)' W i t h i n f o u r : t o s e v e n d a y s a f t e r p a r t u r i t i o n c o p u l a t i o n t a k e s p l a c e ; t h e cow t h e n goes t o sea e i t h e r on t h e same day o r t h e day f o l l o w -i n g t h a t on w h i c h c o p u l a t i o n o c c u r r e d , l e a v i n g h e r pup on t h e r o o k e r y . H e r f i r s t s t a y away f r o m t h e r o o k e r y l a s t s a p p r o x -i m a t e l y s i x d a y s . She r e t u r n s f o r one t o two d a y s and t h e n r e - e n t e r s t h e sea f o r an a v e r a g e o f e i g h t d a y s ; e a c h s u c c e s s i v e - 61i -t r i p t o s e a becomes l o n g e r . The pups f i r s t v e n t u r e i n t o t h e w a t e r i n A u g u s t ( B a k e r , 1957) and f r o m A u g u s t t o O c t o b e r o r November, when abandoned by t h e cows, t h e y g r a d u a l l y l e a r n t o f e e d f o r t h e m s e l v e s . P u r s e a l pups have t r i p l e d t h e i r b i r t h w e i g h t by O c t o b e r . The l a c k o f f o o d i n w a t e r s a d j a c e n t t o t h e r o o k e r i e s may p r o v i d e an e x p l a n a t i o n f o r t h e l e n g t h y t r i p s o f p o s t - p a r t u m f e m a l e s . D r a g g i n g o p e r a t i o n s ( W i l k e and Kenyon, 1954) a n d p e l a g i c s t o m a c h samples i n d i c a t e t h a t o n l y a l i m i t e d f o o d s u p p l y i s a v a i l a b l e w i t h i n a r a d i u s o f 30 m i l e s o f t h e P r i b i l o f I s l a n d s . E i g h t y - f i v e p e r c e n t o f t h e stomachs c o l l e c t e d w i t h i n t h i s 3 0 - m i l e r a d i u s a r e empty ( N i g g o l , e t a l . , i 9 6 0 ) . These a u t h o r s s u g g e s t t h a t t h e 1.5 t o 2 m i l l i o n s e a l s i n t h i s a r e a d u r i n g t h e s i x months f r o m J u n e t o November have r e d u c e d t h e a v a i l a b l e f o o d , p a r t i c u l a r l y b o t t o m f i s h . - Salmon m i g r a t e p a s t t h e P r i b i l o f I s l a n d s b u t a r e s e l d o m t a k e n b y f u r s e a l s ( W i l k e and Kenyon, 1954)* Chapman (1961) has s u g g e s t e d t h a t t h e l a c k o f f o o d i n t h i s a r e a may e x p l a i n t h e h e a v y m o r t a l i t y o f f u r s e a l p u p s . 2. Sea l i o n s P u p p i n g b e g i n s d u r i n g t h e l a s t week i n May and I s f i n i s h e d b y t h e end o f J u n e ( P i k e and M a x w e l l , 1958? p e r s o n a l o b s e r v a t i o n s made d u r i n g 1 9 5 9 ) ' The r e l a t i o n s h i p b e t w e e n t h e p u p p i n g and b r e e d i n g s e a s o n and f e e d i n g h a b i t s o f male, and female s e a l i o n s i s shown i n a s e r i e s o f samples c o l l e c t e d f r o m May t o September. T a b l e X compares the p e r c e n t a g e o f empty stomachs t o t h o s e w i t h f o o d I n t h e s e s a m p l e s . N o r m a l l y , a p p r o x i m a t e l y s i x t y - 6 5 -Table X. Changing ratio of stomachs with food to empty stomachs through-out the pupping and breeding season i n 228 male and female sea lio n stom-achs. Pups not included, (Data from present investigation only.) Male Female Food Empty Food Empty May 2 22-29 F2 14 10 13 18 Rookeries (58.3) (41.7) (41.9) (58.1) June 5-18 F 16 5 15 40 Rookeries % (76.1) (23.9) (27.2) (72.8) July 3-22 F 2 7 12 9 Rookeries % (57.1) (42.9) September 21-30 F 2 0 16 9 Rookeries lo (64.0) (36.0) Non-breeding F 15 10 11 4 May 21 - August 17 % • (60.0) (40.0) (73.3) (26.7) Frequency of occurrence 2 \ , Per cent frequency of occurrence - 66 -per cent of sea l i o n stomachs collected during the daylight hours contain food. During the l a s t week i n Hay males have taken up t e r r i t o r i e s but are feeding r e g u l a r l y as 58$ of stomachs con-t a i n food. The females, which have just started to pup, show the f i r s t signs of a decrease i n food intake, with only 1).2$ of stomachs containing food. The next period of observation, June 5-18, i s during the peak of the pupping period and presumably there i s l i t t l e breeding a c t i v i t y on the part of the males. This sample of 21 males indicates an increase i n feeding. Female food intake Is at a minimum,with only 27$ of female stomachs containing food. The probable explanation for the high percentage of empty female stomachs at t h i s time i s that cows are remaining with t h e i r newborn pups. The f i r s t three weeks i n July indicate a complete reversal of the June s i t u a t i o n . Feeding i s at a minimum i n the male population, but i s nearly normal for the females. Although the male sample i s small I believe the high frequency of empty stomachs (seven out of nine examined) accurately r e f l e c t s the f a c t that many males are busy maintaining t e r -r i t o r i e s and breeding. The cows have finished pupping, l a c t a -t i o n i s well i n progress and normal feeding has been re-esta-blished (57$ of stomachs with food). Although no detailed study of sea l i o n breeding behaviour comparable to Bartholomew and Hoel's (1953) fur seal study i s available, i t i s probable that sea l i o n cows i n contrast to the fur seal cows, do not leave t h e i r pups f o r extended periods of time. Food i s - 67 -abundant i n the immediate v i c i n i t y o f the sea l i o n r o o k e r i e s (see below) and t h e cows' f e e d i n g t r i p s are p r o b a b l y o n l y of a few h o u r s ' d u r a t i o n . The l a s t sample, c o l l e c t e d d u r i n g l a t e September i s p r e d o m i n a t e l y a female sample. By t h i s time n e a r l y a l l the b u l l s and many cows w i t h o u t pups have d e p a r t e d f o r more p r o -t e c t e d w a t e r s , l e a v i n g the l a c t a t i n g cows and pups on the r o o k e r i e s . F e e d i n g by the a d u l t cows i s p r o b a b l y a t a maxi-mum, w i t h 65$ of stomachs c o n t a i n i n g f o o d . Pups have more t h a n doubled t h e i r b i r t h w e i g h t and make heavy n u t r i t i o n a l demands on the cows. I t i s not known when l a c t a t i o n c e a s e s . However, o b s e r v a t i o n s of f e m a l e s s u c k l i n g a n i m a l s 12 and 15 months o l d i n d i c a t e t h a t up t o 25$ o f the y e a r l i n g s are not c o m p l e t e l y weaned. I n some i n s t a n c e s a y e a r l i n g sea l i o n w i l l be n u r s i n g , and s u p p l e m e n t i n g t h i s m i l k d i e t w i t h f i s h , e.g., on J u l y 6, 1959* a y e a r l i n g sea l i o n was c o l l e c t e d w i t h m i l k and a r a t -f i s h i n i t s stomach. I n c r e a s e d numbers of sea l i o n s on r o o k e r i e s d u r i n g the summer months c o u l d s e r i o u s l y r e duce s t o c k s o f f i s h a d j a c e n t t o such r o c k s . E x p l o r a t o r y f i s h i n g (page 85) has shown, however, abundant f o o d s u p p l i e s a d j a c e n t t o Cape S t . James and the S c o t t I s l a n d r o o k e r i e s . 3. Harbour s e a l s D u r i n g the a c t u a l p u p p i n g p e r i o d f o o d i n t a k e i s a t a minimum. Only f i v e stomachs c o n t a i n e d f o o d i n \\$ c o l l e c t e d on the Skeena R i v e r d u r i n g the peak of the p upping p e r i o d . How l o n g t h i s p e r i o d of f a s t c o n t i n u e s i s not d e f i n i t e l y known, but - 68 -i n t h e c a s e o f t h e Skeena R i v e r p o p u l a t i o n p r o b a b l y o n l y u n t i l t h e a d u l t s move down r i v e r t o t h e G i b s o n I s l a n d a r e a . Prom F i s h e r ' s (1952) d a t a i t i s e v i d e n t t h a t b y A u g u s t h a r b o u r s e a l pups, b o r n i n J u n e , a r e f e e d i n g on t h e i r own. T h e s e o b s e r v a t i o n s a r e s t r e n g t h e n e d b y t h o s e o f McNaughton ( p e r s o n a l c o m m u n i c a t i o n ) who has o b s e r v e d t h a t t h e f i r s t pups a r e b o r n d u r i n g t h e l a s t week o f May and p u p p i n g r e a c h e s a p e a k a b o u t t h e m i d d l e o f J u n e . T h i s i s c o m p a r a b l e t o t h e s e a l i o n p u p p i n g b e h a v i o u r . However, Mr. McNaughton n o t e d t h a t I n c o n t r a s t t o s e a l i o n p u p s , the- h a r b o u r s e a l pups a r e q u i t e c a p a b l e o f l o o k i n g a f t e r t h e m s e l v e s w i t h i n one month o f b i r t h , and a t t h i s e a r l y age a r e abandoned by t h e cows. 11. F a s t i n g The phenomena o f f a s t i n g among p i n n i p e d s h as b e e n r e f e r r e d t o b y s e v e r a l a u t h o r s . Some a d u l t male n o r t h e r n f u r s e a l s w i l l f a s t f o r two months w h i l e m a i n t a i n i n g t h e i r harems ( B a r t h o l o m e w and H o e l , 1953); t h e s o u t h e r n e l e p h a n t s e a l f a s t s , f o r o v e r two months i n t h e w i l d and 100 days i n c a p t i v i t y (Laws, 1956); a monk s e a l u nderwent a f o u r - m o n t h f a s t i n c a p -t i v i t y ( S c h e f f e r , 1958). H o w e l l (1930) r e f e r s t o t h e "many weeks" o f f a s t t h a t a male s e a l i o n undergoes.when g u a r d i n g h i s harem, w h i l e P i k e (1958), when d i s c u s s i n g t h e f o o d h a b i t s o f t h e n o r t h e r n s e a l i o n , o b s e r v e s t h a t " . . . d u r i n g a l a r g e p a r t o f t h e y e a r most o f t h e p o p u l a t i o n i s f a s t i n g " . S e a s o n a l f a s t i n g by s e a l i o n s and h a r b o u r s e a l s h a s been e x a m i n e d . Female s e a l i o n s do n o t e a t w h i l e p u p p i n g , a p e r i o d o f a few days o n l y . Harem b u l l s may n o t f e e d f o r a t l e a s t p a r t o f J u l y , w h i l e m a i n t a i n i n g harems. However, - 6 9 -a p r o l o n g e d f a s t does n o t o c c u r i n t h e s e a l i o n p o p u l a t i o n ; t h e p o s s i b i l i t y of s u c h an o c c u r r e n c e c a n n o t be s u g g e s t e d to m i n i m i z e t h e e f f e c t o f s e a l i o n p r e d a t i o n upon c o m m e r c i a l l y v a l u a b l e f i s h e s . The l i m i t e d h a r b o u r s e a l d a t a i n d i c a t e t h a t p o s t -p a r t u m cows i n t h e Skeena R i v e r a r e a u n d e r g o a f a s t f o r a t l e a s t p a r t o f J u n e . S u m m a r i z i n g t h e a v a i l a b l e i n f o r m a t i o n r e g a r d i n g p i n -n i p e d f o o d h a b i t s and r e p r o d u c t i o n t h e f o l l o w i n g was f o u n d : (a) P u r s e a l s : P r e s e n t e v i d e n c e r e g a r d i n g male f e e d i n g b e h a v i o u r on r o o k e r i e s i s c o n t r a d i c t o r y . B a r t h o l o m e w and H o e l ( 1 9 5 3 ) s t a t e t h a t harem b u l l s f a s t f o r two months; R u s s i a n i n v e s t i g a t o r s have f o u n d t h i s does n o t a l w a y s o c c u r and a f r e q u e n t exchange o f b u l l s i n t h e harem may t a k e p l a c e . Stomachs f r o m most young m a l e s c o l l e c t e d c o m m e r c i a l l y a r e empty. F e m a l e s f a s t f o r a b o u t t e n i d a y s d u r i n g t h e p u p p i n g p e r i o d and t h e n s t a r t f e e d i n g , b u t may be f o r c e d t o make e x t e n s i v e f o r a g e s t o sea f o r f o o d . (b) Sea l i o n s : A f a s t o c c u r s f o r a few d a y s d u r i n g J u n e ( e x a c t number o f d a y s n o t known) w h i l e the cows pup. Upon t h e t e r m i n a t i o n o f t h i s f a s t f o o d i n t a k e i s i n c r e a s e d t o s u s t a i n t h e r a p i d l y g r o w i n g pup. Harem m a s t e r s p r o -b a b l y f a s t d u r i n g p a r t o f J u l y when t h e y a r e m a i n t a i n i n g t h e i r harems. ( c ) H a r b o u r s e a l s : H a r b o u r s e a l s on t h e Skeena R i v e r u n d e r g o a p o s t - p a r t u m f a s t d u r i n g J u n e , a l t h o u g h t h e e x a c t l e n g t h o f t h i s f a s t i s n o t known. - 70 -H. I n t e r s p e c i f i c c o m p e t i t i o n The t e r m c o m p e t i t i o n as u s e d h e r e r e f e r s t o an i n t e r s p e c i f i c i n t e r a c t i o n w h i c h a d v e r s e l y a f f e c t s t h e g r o w t h and s u r v i v a l of•• i n d i v i d u a l s o f one s p e c i e s by a n o t h e r d o m i n a n t o r more s u c c e s s f u l s p e c i e s (Odum, i960) . P u r s e a l s , s e a l i o n s and h a r b o u r s e a l s have been f o u n d t o g e t h e r o n l y i n K n i g h t I n l e t and B a r k l e y Sound. Sea l i o n s and h a r b o u r s e a l s may be s e e n t o g e t h e r o c c a s i o n a l l y a l o n g t h e c o a s t . D u r i n g F e b r u a r y and M a r c h o f most y e a r s , y e a r l i n g f u r s e a l s c o n g r e g a t e t o w a r d s t h e head o f K n i g h t I n l e t , w h i c h i s f o u r m i l e s wide. D u r i n g March, 196l , t h e r e were a p p r o x i m a t e l y 100 f u r s e a l s i n m i d - c h a n n e l a t a d i s t a n c e g r e a t e r t h a n one m i l e f r o m e i t h e r s h o r e and two m i l e s ' f r o m t h e e s t u a r y o f t h e K l e e n R i v e r a t t h e head o f t h e i n l e t . When t h i s areavwas sampled o n l y f o u r f u r s e a l s had v e n t u r e d i n s h o r e i n t h e d i r e c t i o n o f t h e e s t u a r y . These f o u r had been f e e d i n g e x c l u s i v e l y on e u l a c h o n . S i x t y s e a l s c o l l e c t e d i n ' t h e m i d d l e o f t h e I n l e t had b e e n f e e d i n g on s q u i d . D u r i n g t h i s same p e r i o d a p p r o x i m a t e l y 30 sea l i o n s I n g r o u p s o f f o u r t o t e n were r a n g i n g ; mp and down t h e s h o r e , m o v i n g o c c a s i o n a l l y i n t o t h e m i d d l e of t h e i n l e t o r t h e e s t u a r y o f t h e r i v e r . One s e a l i o n c o l l e c t e d h ad b e e n f e e d i n g on dog-f i s h and w h i t i n g . x x One s e a l i o n s t o m a c h c o l l e c t e d and examined by D e p a r t m e n t o f F i s h e r i e s o f f i c i a l s d u r i n g A p r i l , i960, i n K n i g h t I n l e t , c o n t a i n e d e u l a c h o n . - 7 1 -T w e n t y - f i v e h a r b o u r s e a l s were f o u n d a t t h i s t i m e i n t h e e s t u a r y o f t h e K l e e n a K l e e n R i v e r ; some s o l i t a r y i n d i -v i d u a l s were f o u n d a l o n g t h e s h o r e of t h e i n l e t , m a i n t a i n i n g a s t a t i o n a r y p o s i t i o n , c l o s e t o t h e b e a c h . Two h a i r s e a l s f r o m t h e r i v e r e s t u a r y had b e e n f e e d i n g on e u l a c h o n . T h e r e f o r e , h a r b o u r s e a l s p l u s t h e few f u r s e a l s w h i c h had moved i n t o t h e K l e e n a K l e e n e s t u a r y were f e e d i n g on e u l a c h o n . The m a j o r i t y of t h e f u r s e a l s were f e e d i n g on s q u i d , w h i l e t h e one s e a l i o n c o l l e c t e d had b e e n f e e d i n g on d o g f i s h and w h i t i n g . D u r i n g F e b r u a r y , 1 9 5 8 , t h e t h r e e p i n n i p e d s were f o u n d t o g e t h e r i n B a r k l e y Sound; d i s t r i b u t i o n t h e r e was s i m i l a r t o t h a t o b s e r v e d i n K n i g h t I n l e t . The f u r s e a l s were g r e a t e r t h a n one m i l e f r o m s h o r e ; s e a l i o n s and h a r b o u r s e a l s were b o t h c l o s e t o s h o r e a l t h o u g h t h e s e a l i o n s were u s u a l l y a c t i v e l y swimming, i n c o n t r a s t t o t h e more s e d e n t a r y h a r b o u r s e a l s . A t t h i s t i m e t h e r e were a p p r o x i m a t e l y 2 5 f u r s e a l s , 3 0 0 s e a l i o n s , and an unknown number o f h a r b o u r s e a l s i n t h e a r e a . Stomach c o n t e n t s I n d i c a t e d t h a t f u r s e a l s ( f o u r stomachs w i t h f o o d ) were f e e d i n g on h e r r i n g , r a t f i s h , hake and s m e l t s , w h i l e s e a l i o n s (two s t o m a c h s ) were f e e d i n g on h e r r i n g and w h i t i n g ; one h a r b o u r s e a l c o l l e c t e d was f e e d i n g on hake. A l t h o u g h b o t h f u r s e a l s and sea l i o n s were f e e d i n g on h e r r i n g , t h e s m a l l numbers o f f u r s e a l s i n t h e a r e a , and t h e l a r g e volume o f h e r -r i n g a v a i l a b l e i n , B a r k l e y Sound a t t h a t t i m e o f y e a r , i n d i c a t e d t h a t any a c t i v e c o m p e t i t i o n b e t w e e n t h e s e two s p e c i e s was u n l i k e l y , p a r t i c u l a r l y when t h e i r r e l a t i v e d i s t r i b u t i o n s were c o n s i d e r e d . - 72 -Sea l i o n s are rarely found offshore i n the v i c i n i t y of fur seals, and when located are d i f f i c u l t to k i l l . However, on May 21, I96l, a young sea l i o n was collected 10 miles out-side Tofino i n 30 fathoms of water. This animal, k i l l e d i n waters where fur seals were feeding predominately on herring (75$ hy volume during May, 196l) had been feeding on lingcod and on unidentified f l a t f i s h . Pur seal stomachs occasionally contain f l a t f i s h , but lingcod have never been i d e n t i f i e d i n stomachs collected i n B r i t i s h Columbia waters. On Triangle Island a small population of 25 harbour seals l i v e near 500-600 sea l i o n s . The sea l i o n s haul out on small rocks situated a few yards to one mile off Triangle Island, while harbour seals haul out on the beaches of the main islan d spend considerable time i n protected pools behind the outer reefs (Figure l 6 ) . Occasionally harbour seals have been seen outside the surf, near a sea l i o n rock or a group of swimming sea l i o n s , but no animosity has been observed between the two species. Two harbour seals collected had fed on lingcod and small sablefish, neither of which have been i d e n t i f i e d i n an examination of 35 sea.lion stomachs with food from Triangle Island. Thus >inter-specific competition appears to be neg-l i g i b l e i n B r i t i s h Columbia waters even though i t i s known that i n several Instances the same species of f i s h may be preyed upon by each of the three pinnipeds-.:. I i i the r e l a t i v e l y few areas where the three predators (or only two of them) occur together, intermingling i s rare. When stomach contents i n d i -cate that the same food species i s being preyed upon by two, Figure 16. T r i a n g l e I s l a n d Top: harbour s e a l h a b i t a t behind breakers. Sea l i o n rock i n f a r r i g h t background Bottom: sea l i o n rock w i t h T r i a n g l e I s l a n d i n background - 7k -or the three, predators i n the same area and at the same time, the numbers of predators are so few, and the prey species i s so abundant that competition i s u n l i k e l y . Where larger populations are concerned, however, competition may exist. Intermingling of adult fur seals, sea l i o n s and harbour seals was observed during June, 1962, on the Portlock Bank, Gulf of Alaska, 30 to liO miles from shore. Whether or not active competition for food occurred was not determined as only fur seals were co l l e c t e d . These l a t t e r were feeding exclusively on sandlance. Sea l i o n s were observed at the surface eating r o c k f i s h twice and salmon once. EFFECT OF SEAL AND SEA LION PREDATION UPON BRITISH COLUMBIA'S COMMERCIAL FISHERY Two problems must be faced when considering pinniped predation upon the commercial f i s h e r y : (a) the e f f e c t of seal and sea l i o n predation upon f i s h stocks; (bj the e f f e c t of this predation upon the commercial fisherman and h i s gear. This study has attempted to f i n d the answer to (a). The answer to (b) requires further i n v e s t i g a t i o n i n the form of questionnaires and Interviews with fishermen. The Department of Fisheries i s at present undertaking such a program. The amount of salmon and herring eaten by sea l i o n s and harbour seals has been estimated i n Appendix 1. There are i n s u f f i c i e n t data to estimate the amounts of herring and salmon eaten by fur seals. - 75 -A. F u r s e a l s S p e c i e s o f g r e a t e r o r l e s s e r e c o n o m i c i m p o r t a n c e make up a l a r g e p a r t o f t h e f u r s e a l d i e t i n B r i t i s h C o l u m b i a w a t e r s . Over t h e p a s t f o u r y e a r s t h e y have t o t a l l e d 65$ o f t h e c o n t e n t s e xamined, and i n c l u d e h e r r i n g , salmon, h a k e , cod, s a b l e f i s h , r o c k f i s h and f l a t f i s h . However, o n l y p r e d a t i o n u pon h e r r i n g , s a l m o n and some o f t h e s p e c i e s e x p l o i t e d by t h e t r a w l f i s h e r y c a n be r e g a r d e d as p o t e n t i a l l y s e r i o u s , as i t i s t h e s e g r o u p s o f f i s h w h i c h a t p r e s e n t a r e b e i n g h e a v i l y e x p l o i t e d b y man. No c o n c e r n i s e x p r e s s e d r e g a r d i n g p r e d a t i o n upon o t h e r c o m m e r c i a l l y v a l u a b l e f i s h e s as t h e y a r e e i t h e r f i s h e d s p a s -m o d i c a l l y o r t a k e n i n v e r y s m a l l q u a n t i t i e s by f u r s e a l s . 1. H e r r i n g H e r r i n g a r e t h e most f a v o u r e d f i s h s p e c i e s t a k e n by f u r s e a l s i n B r i t i s h C o l u m b i a w a t e r s , and c o n t r i b u t e i i 3 $ t o t h e t o t a l d i e t ( F i g u r e 1 3 ) . The n o r t h w a r d m i g r a t i o n o f f u r s e a l s o f f t h e west c o a s t o f V a n c o u v e r I s l a n d c o i n c i d e s w i t h t h e o f f s h o r e movement o f h e r r i n g o u t o f B a r k l e y and C l a y o q u o t Sounds a f t e r s pawning, w h i c h r e a c h e s a p e a k d u r i n g m id-March. An i n d e x o f t h e s i z e o f t h e a d u l t h e r r i n g p o p u l a t i o n i s computed on t h e b a s i s o f " m i l e s of spawn" d e p o s i t e d . The amount o f spawn d e p o s i t e d i s e s t i m a t e d e a c h y e a r by t h e D e p a r t m e n t o f F i s h e r i e s and c o n s i s t s o f m e a s u r i n g t h e l e n g t h and w i d t h o f e a c h spawn d e p o s i t i o n . I n a d d i t i o n , i n t e n s i t y o f d e p o s i t i o n i s e x p r e s s e d as one o f f i v e b r o a d c a t e g o r i e s b a s e d on t h e numbers of eggs p e r l i n e a r i n c h o f n a r r o w b l a d e d v e g e t a t i o n , o r p e r s q u a r e i n c h o f b r o a d -l e a f e d v e g e t a t i o n . The spawn i n d e x , e x p r e s s e d as " m i l e s o f - 76 -spawn", i s then calculated by summing the lengths of a l l spawnings, afte r adjustments have been made f o r differences i n i n t e n s i t y and width (Outram, I96l). Indices of abundance f o r 1958, 1959, I960 and 1961 have been compared with the per cent frequency occurrence of herring found i n stomachs collected i n waters between Barkley and Clayoquot Sounds (Figure 17)• The trend of a sharp decrease i n the size of the herring spawning population as exhibited by the "miles of spawn" index from 1958 to 1959, followed by a l e v e l l i n g off from 1959 to i960, and an increase i n 1961 appears to be f a i r l y well duplicated by the presence of herring i n seal stomachs. Thus, the magnitude of fur seal predation upon her-r i n g i s apparently related to the abundance of spawning herring. 2. Salmon Salmon have occurred only 59 times (5*8% frequency of occurrence) i n a t o t a l of 2113.stomachs examined. Fur seals do not appear to show a preference f o r salmon and they may, i n f a c t , prefer smaller f i s h such as herring, when the two types of prey are available. The only i n d i c a t i o n of salmon aval l a b i l i t y i s the presence of the t r o l l i n g f l e e t off southern Vancouver Island: seals, collected i n the v i c i n i t y of t r o i l e r s presumably have had an opportunity to prey upon salmon. During i960, i n nine stomachs containing food collected i n the v i c i n i t y of the t r o l l i n g f l e e t on La Perouse Bank, none contained salmon. Herring was the predominate food species. In 1959, six stomachs containing herring were collected i n an area where salmon were reported as p l e n t i f u l by t r o l l e r s . During the 196l pelagic c o l l e c t i n g program there was an apparent 77 lb % frequency occur. M i l e s of spawn Ik - If »58 1959 1960 1961 Year Figure 17. Per cent frequency of occurrence of h e r r i n g i n fur s e a l stomachs "off southern Vancouver I s l a n d and m i l e s of h e r r i n g spawn i n Barkley and Clayo-quot Sounds (139 stomachs). - 78 -i n c r e a a e o f s m a l l coho o f f B a r k l e y and C l a y o q u o t Sounds, as r e p o r t e d b y c o m m e r c i a l t r o l l e r s . However, s e a l stomachs were empty when c o l l e c t e d i n t h e v i c i n i t y o f t r o l l e r s . D e s p i t e t h e s e n e g a t i v e r e s u l t s t h e o c c u r r e n c e o f s a l m o n i n stomachs i n c r e a s e d d u r i n g 196l ( o v e r i960), w h i c h p r o b a b l y r e f l e c t e d an i n c r e a s e d abundance o f s m a l l s almon. T h e r e i s no c o r r e l a t i o n b e t w e e n f r e q u e n c y o f o c c u r -r e n c e o f s a l m o n i n s e a l stomachs and t h e c o m m e r c i a l c a t c h of s p r i n g and coho salmon i n t h e a r e a s u n d e r s t u d y . 3. T r a w l f i s h e r y The m i g r a t o r y p a t h o f many f u r s e a l s p a s s e s a c r o s s most of t h e t r a w l f i s h i n g b anks, and s e v e r a l f i s h s p e c i e s i d e n -t i f i e d i n s e a l stomachs a r e a l s o e x p l o i t e d by t h i s f i s h e r y . D u r i n g F e b r u a r y and March, f r o m 1959 t o 1962 i n c l u -s i v e , f u r s e a l s were h u n t e d i n t h e v i c i n i t y o f t h e W h i t e Rock t r a w l i n g g r o u n d i n n o r t h e r n H e c a t e S t r a i t . A t o t a l o f 38 stomachs w i t h f o o d were c o l l e c t e d d u r i n g t h e s e f o u r y e a r s . C a t c h s t a t i s t i c s f o r t h e two months u n d e r c o n s i d e r a t i o n , t o t a l l e d f o r t h r e e y e a r s , have b e e n compared w i t h s e a l s t o m a c h c o n t e n t s ( F i g u r e 18). Th e s e c o m m e r c i a l d a t a i n c l u d e n o t o n l y f o o d f i s h , b u t a l s o f i s h s p e c i e s c a u g h t f o r mink o r p e t f o o d and a r e t h e r e f o r e r e p r e s e n t a t i v e o f b o t t o m f i s h a v a i l a b l e on t h e g r o u n d s . T h e r e i s l i t t l e r e l a t i o n s h i p between t h e two s e t s o f s t a t i s t i c s i l l u s t r a t e d i n F i g u r e 18. C o m m e r c i a l g r e y cod a r e l a r g e mature f i s h c a u g h t between ij-5 and 63 f a t h o m s , w h i c h may be t o o deep f o r f u r s e a l s (Kenyon, 1951)• W h i t i n g , a l t h o u g h a p p a r e n t l y n o t t o o abu n d a n t , a r e se c o n d i n i m p o r t a n c e t o h e r r i n g ' i n . t h e f u r s e a l d i e t . T h e r e a r e v i r t u a l l y no s a b l e f i s h o f F i g u r e 18. Trawl f i s h e r y catch s t a t i s t i c s f o r 1959-1961 (White Rocks f i s h i n g grounds), and f u r s e a l stomach contents c o l l e c t e d from t h i s v i c i n i t y . - 80 -commercial s i z e i n t h i s area, but small s a b l e f i s h do show In some of the t r a w l catches; these s m a l l e r f i s h are taken by s e a l s . S t u d i e s conducted by the F i s h e r i e s Research Board of Canada have shown that s a b l e f i s h , w h i t i n g and h e r r i n g f r e -q u e n t l y s c h o o l t o g e t h e r . When l o o k i n g f o r f i s h other than h e r r i n g caught i n h e r r i n g purse seines, the only two s p e c i e s i n l a r g e numbers, other than h e r r i n g , were s m a l l s a b l e f i s h ( 9 " - L I L " ) and sm a l l w h i t i n g ( l l n - l l | . " ) . E x p l o r a t o r y f i s h i n g w i t h mid-water t r a w l s i n Saanich I n l e t i n d i c a t e d t h a t h e r r i n g and sma l l w h i t i n g (12") were w e l l o f f the bottom (Barraclough and Herlin v e a u x , I 9 6 l ) . T h e r e f o r e , s m a l l w h i t i n g and s a b l e f i s h r i s e o f f the bottom and i n some cases mingle with the h e r r i n g s c h o o l s ; commercially v a l u a b l e grey cod and f l a t f i s h remain on the bottom, and are seldom preyed upon by f u r s e a l s . B. Sea l i o n s Commercially v a l u a b l e f i s h c o n t r i b u t e d 52.5$ to the t o t a l sea l i o n sample. These i n c l u d e h e r r i n g , salmon, hake, grey cod, w h i t i n g , f l a t f i s h , h a l i b u t , s a b l e f i s h , l i n g c o d and r o c k f i s h . S e v e r a l of these f i s h e r i e s are not f u l l y u t i l i z e d by man and only the h e r r i n g , salmon and h a l i b u t f i s h e r y w i l l be d i s c u s s e d i n d e t a i l . 1. H e r r i n g Compared t o f u r s e a l s , sea l i o n s do not rejLy so much upon h e r r i n g as a food; approximately 10$ of the sea l i o n s ' d i e t i s h e r r i n g compared t o 1+3$ f o r f u r s e a l s . N e v e r t h e l e s s , i n c e r t a i n l o c a l i t i e s sea l i o n s prey e x t e n s i v e l y upon h e r r i n g - 81 -d u r i n g t h e w i n t e r months, and a r e o b s e r v e d by f i s h e r m e n swimming c l o s e t o , o r i n , t h e i r h e r r i n g s e i n e s , f e e d i n g on h e r r i n g . As m e n t i o n e d e a r l i e r , h e r r i n g m i g r a t e i n t o B a r k l e y Sound d u r i n g t h e w i n t e r months t o spawn. E a c h w i n t e r , sea l i o n s a r e a l s o f o u n d i n t h e s e w a t e r s , r e m a i n i n g u n t i l A p r i l . A t o t a l o f 30 stomachs have b e e n examined f r o m t h e B a r k l e y Sound a r e a s i n c e 19lii. H e r r i n g , w h i c h o c c u r r e d l6 t i m e s i n a t o t a l o f 29 i d e n t i f i a b l e f o o d i t e m s , was the. most i m p o r t a n t f o o d i t e m ( T a b l e X I ) . However, t h e r e l a t i v e l y h i g h number o f o c t o p u s and r o c k f i s h r e m a i n s i n d i c a t e t h a t h e r r i n g were n o t t h e e x c l u s i v e d i e t o f sea l i o n s , e ven i n a r e a s o f h e r r i n g abun-d a n c e . T a b l e X I . C o n t e n t s o f 23 s e a l i o n stomachs f r o m B a r k l e y Sound: 1I4. c o l l e c t e d i n December, 1915 (Newcombe e t a l . , 1918); n i n e c o l l e c t e d d u r i n g t h e p r e s e n t i n v e s t i g a t i o n . S p e c i e s F r e q u e n c y % F r e q u e n c y H e r r i n g 16 55.2 R o c k f i s h 3 10.3 O c t o p u s 3 10.3 S k a t e 1 3-* L i n g c o d 1 3.5' F l a t f i s h 2 6.8 W h i t i n g 1 3-5 S q u i d 1 3.5 D o g f i s h 1 3.5 T o t a l 29 2. S a l m o n The o v e r a l l p e r c e n t a g e c o n t r i b u t i o n of s a l m o n t o b o t h t h e f u r s e a l and s e a l i o n d i e t i s q u i t e s i m i l a r : 5.6$ f o r s e a l i o n and 5«8$ f o r f u r s e a l s . However, p r e d a t i o n by - 8 2 -fur seals begins when salmon are s t i l l offshore, during March, A p r i l and May i n waters examined. Sea l i o n predation begins i n June, and during J u l y and August apparently increases (Table XII). Following the summer breeding a c t i v i t y most male sea lions and females without pups leave the rookeries and move to haul-out rocks closer to the mainland, or into the i n l e t s . During t h i s time there i s a further predation upon salmon. The Scott Island rookery, situated at the north 'end of Vancouver Island, i s advantageously located f o r sea l i o n predation upon the large salmon runs moving toward the spawning r i v e r s on the mainland. During the years under study t h i s pop-u l a t i o n has varied from 1 , 7 ° ° to 1 , 1 0 0 adults per breeding season. From a t o t a l of 6 3 occurrences of i d e n t i f i a b l e food remains only four (six per cent) were salmon (Table XII). How-ever, this f i g u r e may be misleadingly low. There was v i r t u a l l y no predation upon salmon i n thi s area during May, June and September, but salmon occurred i n three of the four stomachs collected during July and August. Commercial catches of sockeye, coho and pink salmon i n f i s h e r i e s area 1 2 , which includes the Scott Islands, reach a peak during J u l y and August. Therefore, the main salmon runs pass these rookeries during the months when there are very few data on sea l i o n feeding habits. Although no direc t evidence i s available regarding the e f f e c t of sea li o n s on these salmon runs, Figure 1 9 com-pares the t o t a l salmon catch i n area 1 2 with the reduction of the Scott Island sea l i o n population since 1 9 5 6 . The reduction i n sea l i o n s has not resulted In a corresponding increase i n - 8 3 -the commercial salmon catch. Table XII. Contents from 5 2 sea l i o n stomachs from the Scott Islands and adjacent waters. (Data from present in v e s t i g a t i o n only. ) Month Stomach contents (frequency of occurrence) Salmon Octopus Rockfish Dogfish Hake Whiting Squid ' Mackereljack Herring Ratfish Flatfish TOTALS May June J u l y August September 1 0 II 5 2 1 2 2 1 1 6 1 7 2 1 * 3 1 1 6 7 2 1 1 1 1 1 2 0 Salmon predation by the Cape St. James sea lions during the summer months of June, July and August may not be as serious as around the Scott Islands. During July, the only month when salmon were encountered In stomachs from Cape St. James, these species were found once i n a t o t a l of ten iden-t i f i a b l e food occurrences. Following the gradual breakup of the breeding pop-ula t i o n , which begins during August and early -September, some sea l i o n s follow and prey upon salmon i n the coastal i n l e t s . Stomachs from three female sea l i o n s , collected at the mouth of Klinkwol Bay i n the Queen Charlotte Islands, October, i 9 6 0 , - 81+ -ra T S C o PH o M c o •H r r j CVJ • H H CO O <• - P as co O <D •H O CD ;E .C rH ra as *H CO fx, as •H o U <D s E o o 35 r 30 20 -10 -3500 - 3000 - 2000 - 1000 1954 1955 1956 1957 1958 1959 i960 1961 Y e a r F i g u r e 19: Salmon c a t c h e s ( a l l s p e c i e s ) and t h e d e c r e a s i n g s e a l i o n p o p u l a t i o n i n f i s h e r i e s a r e a 12, f r o m 1951+ t o 1961. - 85 -contained remains of pink and chum salmon. These three were pregnant and had therefore moved from a breeding rookery (pro-bably Gape St. James) some time during the late summer. 3. Halibut Although sea lions eat halibut, there i s l i t t l e docu-mental evidence to help assess the extent of t h i s damage. Hal-ibut were i d e n t i f i e d once from a stomach collected on the west coast of the Queen Charlotte Islands; a sea l i o n was observed eating a halibut at the surface i n northern Hecate S t r a i t on March 6, 1959. Prom the sc a r c i t y of halibut i n stomach contents, i t may be guessed that sea l i o n predation i s not serious enough to reduce e x i s t i n g stocks of t h i s species. h* A v a i l a b i l i t y of f i s h around sea l i o n rocks The numbers of f i s h i n the immediate v i c i n i t y of sea l i o n haul-out and breeding rocks was investigated. Fishing was done with stainless steel j i g s . Results from exploratory f i s h i n g cruises were also examined. A large trawling.;ground, 60 square miles i n extent, has recently been found within 15 miles of the Scott Islands' rookeries (Hitz et_ al_., 196l). Catches of rock sole, i n 50 fathoms of water, averaged 750 lbs per hour. In deeper tows (70-120 fathoms) rock f i s h dominated the catches. Sea l i o n s can dive to depths of 100 fathoms, and frequently dive to 60 and 80 fathoms (Kenyon, 1951). The Cape St. James area was also examined f o r e v i -dence of serious sea l i o n depredations upon commercially v a l -uable f i s h e s . Available evidence indicated this to be s l i g h t . Waters adjacent to these rookeries are fished f o r halibut and - 86 -have b e e n f o r many y e a r s . The new d e s e r t e d I n d i a n v i l l a g e o f Skunggwai, on A n t h o n y I s l a n d , 15 m i l e s n o r t h o f t h e s e r o o k e r i e s , r e c e i v e d i t s name f r o m t h e l a r g e numbers o f f i s h , p a r t i c u l a r l y r o c k f i s h , f o u n d i n t h e v i c i n i t y ( D u f f and Kew, 1957). T h i s was b e f o r e any c o n t r o l m e asures were e x e r t e d upon t h e sea l i o n p o p u l a t i o n . The f o l l o w i n g t h r e e o b s e r v a t i o n s i n d i c a t e t h e a v a i l -a b i l i t y of f i s h , m o s t l y r o c k f i s h and l i n g c o d , a r o u n d s e a l i o n r o c k s : (a) A p r i l 7, 1958. S i x l i n g c o d and two r o c k f i s h ( S e b a s t o d e s s p . ) were c a u g h t i n 25 m i n u t e s a t P o l g e r I s l a n d , B a r k l e y Sound, where 200 a d u l t s ea l i o n s were w i n t e r i n g . (b) M a r c h 8, I96l. T h r e e s m a l l l i n g c o d , two r e d s n a p p e r s ( S e b a s t o d e s r u b e r r i m u s ) and two orange s p o t t e d r o c k f i s h ( S e b a s t o d e s m a l i g e r ) were c a u g h t w i t h i n h a l f an h o u r ' s f i s h i n g a t B r i g h t I s l a n d , Queen C h a r l o t t e S t r a i t , where 50 sea l i o n s , m o s t l y l a r g e m a l e s , were h a u l i n g o u t . ( c ) September 26, i960. T h r e e l i n g c o d j i g g e d i n 10 m i n u t e s and i l l l a r g e r e d s n a p p e r s ( S e b a s t o d e s r u b e r r i m u s ) c a u g h t i n one h o u r a t S a r t i n e I s l a n d where 300 a d u l t s w i t h 250 n u r s i n g pups were l o c a t e d . Sea l i o n s have l i t t l e o r no e f f e c t i n s e r i o u s l y r e d u c i n g t h e numbers o f f i s h i n t h e v i c i n i t y o f t h e i r r o o k e r i e s and h a u l - o u t r o c k s . A g e n e r a l o b s e r v a t i o n , w h i c h has b e e n s t r e n g t h e n e d o v e r t h e p a s t f o u r y e a r s of c o l l e c t i n g , i s t h a t l i n g c o d and r o c k f i s h a r e a b u n d a n t n e a r sea l i o n r o c k s . - 87 -C. Harbour seals Pish of commercial value comprise Shf° °? the barbour seal d i e t . These include herring, salmon, eulachon, hake, whiting, f l a t f i s h , s a b l e f i s h and lingcod. Concern i s directed mainly towards the possible e f f e c t of harbour seal predation upon herring and salmon. 1. Herring This species i s important to harbour seals, although the present study may not show i t s true importance. The sample indicates only a 12$ contribution to the t o t a l diet (Figure 13), but herring have been found i n stomachs collected during A p r i l , July, September and November - e s s e n t i a l l y throughout the entire year. There are few, i f any, complaints from the f i s h i n g industry regarding harbour seal predation upon herring. 2. Salmon Harbour seal predation upon salmon may be extensive at certain times of the year. Salmon contributed approximately 30$ to the contents of a sample collected f o r the most part near salmon spawning streams during the f a l l ; sampling indicate that salmon are also eaten during the summer months, pa r t i c u -l a r l y June. However, seals prey on other food even when salmon are abundant. Fisher (1952) discussed the r e l a t i v e Importance of salmon In. the harbour seal diet on the Skeena River during the summer months. He noted' that, although salmon were very numerous, other f i s h species were preyed upon, p a r t i c u l a r l y as the seals moved towards the sea after pupping. Since Fisher study, I|5 more stomachs have been collected from this area and - 88 -examined b y D e p a r t m e n t o f F i s h e r i e s o f f i c i a l s d u r i n g J u n e , 19k&» and J u n e , 1959* F o r t y o f t h e s e were empty i n d i c a t i n g t h a t l i t t l e f e e d i n g o c c u r s on t h e Skeena R i v e r d u r i n g p a r t o f J u n e a t l e a s t . Of t h e f o u r s t omachs w i t h f o o d , s a l mon o c c u r r e d t w i c e , a l a m p r e y once and f e a t h e r s once. F i s h e r a l s o n o t e d t h a t i n a sample o f t h r e e stomachs c o l l e c t e d a t t h e mouth o f t h e F r a s e r R i v e r d u r i n g salmon m i g r a -t i o n s , two stomachs c o n t a i n e d h e r r i n g and one c o n t a i n e d s almon. D u r i n g t h e p r e s e n t i n v e s t i g a t i o n a h a r b o u r s e a l c o l -l e c t e d i n Luxanna Bay, Queen C h a r l o t t e I s l a n d s , was f e e d i n g on h e r r i n g w h i l e p i n k s a l m o n were moving i n t o a c r e e k a t t h e head o f t h e b a y . A t t h e same t i m e t h r e e s e a l s were k i l l e d i n Howe Bay, a p p r o x i m a t e l y 10 m i l e s away, where t h e r e was no s a l m o n s p a w n i n g c r e e k . T h e s e stomachs c o n t a i n e d r o c k f i s h , o c t o p u s and g r e e n l l n g . T h u s , t h e r e was no o b v i o u s movement o f s e a l s f o l l o w i n g t h e s a l m o n ( o r h e r r i n g ) w h i c h were p r e s e n t i n Luxanna Bay. T h i s t y p e o f b e h a v i o u r was a l s o e v i d e n t i n B a r k l e y Sound i n 1958. One h a r b o u r s e a l c o l l e c t e d h ad e a t e n h a k e , a l t h o u g h s p a w n i n g h e r r i n g were i n t h e a r e a . T h e s e o b s e r v a t i o n s on f o o d o t h e r t h a n s a l m o n o r h e r r i n g i n h a r b o u r s e a l stomachs have b e e n r e c o r d e d n o t t o m i n i m i z e t h e p o s s i b l e s e r i o u s n e s s o f s e a l p r e d a t i o n , b u t t o i l l u s t r a t e t h e n e c e s s i t y f o r a c c u r a t e f i g u r e s on numbers o f s e a l s p r e y i n g on s a l m o n . H a r b o u r s e a l s a r e s c a t t e r e d o v e r t h e c o a s t d u r i n g t h e summer and f a l l and i t i s n o t a d e q u a t e t o s a y t h a t as t h e r e i s a t o t a l p o p u l a t i o n o f X s e a l s , a l l a r e f e e d i n g on s a l m o n . I t a p p e a r s t h a t o n l y t h o s e i n t h e v i c i n i t y o f salmon c r e e k s c a n be r e g a r d e d as p o t e n t i a l p r e d a t o r s . - 89 -CONCLUSIONS A. E f f e c t of fur seals, sea l i o n s and harbour seals upon  commercially valuable f i s h Pur seals, sea l i o n s and harbour seals eat f i s h of commercial importance, e s p e c i a l l y herring and salmon. Herring i s the most important food f o r the migrating fur seal herd moving up the B r i t i s h Columbia coast, and f o r the.wintering animals; i t i s preyed upon from January to June. Harbour seals also feed on herring and w i l l take t h i s f i s h whenever i t i s ava i l a b l e . In contrast, sea l i o n s feed upon herring mainly during the winter months. The t o t a l tonnage of herring eaten by sea l i o n s and harbour seals has been estimated at 1t2$0 (2,14,00-13,250) tons, or ii$ (1.0-6.2$) of the average annual commercial catch of 200,000 tons (Appendix 1} Herring are subjected to intense predation throughout t h e i r entire l i f e cycle by many f i s h , birds and mammals. Total mortality of mature and maturing f i s h i s up to 80$, of which an average of 50-60$ res u l t s from natural mortality i n ages f i v e to twelve years (P. H. C. Taylor, personal communication). Pinniped predation, accounting f o r an estimated 5$ of the average annual catch, i s not a serious factor i n herring mor-t a l i t y . Salmon also are taken by these three predators. Migrating f u r seals occasionally take salmon, usually small f i s h , off the west coast of Vancouver Island, as salmon are moving towards coastal waters. Pur seal predation upon salmon cannot be evaluated u n t i l the numbers of seals preying upon - 90 -t h e s e s p e c i e s can he e s t i m a t e d . H a r b o u r s e a l s p r e y upon salmon, p a r t i c u l a r l y d u r i n g t h e f a l l when t h e s a l m o n a r e m oving i n t o t h e r i v e r s . However, h a r b o u r s e a l s do n o t a l w a y s make a s p e c i a l e f f o r t t o c o n g r e g a t e i n a r e a s o f s a l m o n abundance, and when sa l m o n a r e a v a i l a b l e do n o t r e s t r i c t t h e i r d i e t e x c l u s i v e l y t o s a l m o n . Salmon f o r m up t o 30$ o f t h e d i e t o f s e a l s c o l l e c t e d i n t h e mouths o f s a lmon s t r e a m s . Sea l i o n s p r e y upon salmon d u r i n g t h e summer months as t h e s a l m o n m i g r a t e p a s t t h e r o o k e r i e s . I n a d d i t i o n , s e a l i o n s p r o b a b l y f o l l o w t h e s a l m o n i n t o b a y s and r i v e r mouths, and p r e y upon them t h e r e . The t o t a l amount o f s a lmon e a t e n by s e a l i o n s and h a r b o u r s e a l s i s e s t i m a t e d t o be I4..0 (1.2-7.1) m i l l i o n pounds a n n u a l l y , w h i c h i s a p p r o x i m a t e l y 2.5$ (0.8-1]..7$) o f t h e a v e r a g e ll|.8 m i l l i o n pound a n n u a l c o m m e r c i a l c a t c h ( A p p e n d i x 1). Salmon m o r t a l i t y r a t e s a r e h i g h b o t h i n f r e s h w a t e r and t h e o c e a n . Neave (1953) e s t i m a t e d f r e s h w a t e r s u r v i v a l o f p i n k and chum s a l m o n t o v a r y between one p e r c e n t and t w e n t y -f o u r p e r c e n t ; o c e a n s u r v i v a l was assumed t o a v e r a g e a p p r o x -i m a t e l y f i v e p e r c e n t f o r e a c h s p e c i e s . R i c k e r (1962) e s t i -mated a v e r a g e t o t a l l o s s e s o f ocean s o c k e y e t o v a r y f r o m 95$ t o 61+$. P i s h i n g m o r t a l i t y o f r e t u r n i n g a d u l t s a l m o n r a n g e s f r o m 50$ t o 80$, d e p e n d i n g u p o n t h e s p e c i e s ( S h e p a r d and S t e v e n s o n , 1956)' The p r e s e n t s t u d y i n d i c a t e s t h a t s e a l i o n s and h a r b o u r s e a l s t a k e an amount e q u a l t o 2.5$ o f t h e f i s h i n g m o r t a l i t y . What r o l e p r e d a t o r s p l a y i n t h e r e d u c t i o n o f t h e s e p o p u l a t i o n s i s n o t f u l l y u n d e r s t o o d . E l s o n (1962) h a s shown - 91 -that b i r d predation upon young salmon during t h e i r freshwater existence can seriously reduce the number of smolt s entering the sea. No study has yet been made to determine the effect of predators upon salmon during t h e i r ocean existence. Parker (1962) has estimated, on a t h e o r e t i c a l basis, that although a coastal natural mortality factor could be c a l -culated for adult migrant salmon, such mortality was s l i g h t and was of n e g l i g i b l e influence on the t o t a l mortality. This study supports these t h e o r e t i c a l conclusions. I wish to emphasize that knowledge concerning the e f f e c t of pinnipeds, p a r t i c u l a r l y fur seals, upon salmon i s f a r from complete. Although the coastal zone has been studied, i t Is d i f f i c u l t to estimate numbers of migrating fur seals i n t h i s area. In addition, v i r t u a l l y nothing i s known about the feeding habits of adult fur seals which must winter and migrate over much of the mid-North P a c i f i c Ocean. These seals are usually scattered and d i f f i c u l t to hunt; as a r e s u l t very few have been collected farther than 20 0 miles from shore during the present pelagic fur seal program. During June, 19&2, however, a Canadian vessel c o l -lected thirty-seven seals i n the middle of the Gulf of Alaska. Salmon occurred i n ten of the 26 stomachs with food. No con-clusions can be drawn from such a small sample although the d e s i r a b i l i t y of further c o l l e c t i o n s offshore i s indicated. To summarize b r i e f l y : each year sea lions and harbour seals consume an estimated amount of salmon equivalent to 2.5$ of the annual commercial salmon catch and an estimated amount of herring equivalent to h$> of the annual commercial - 92 -herring catch. Predation at thi.s l e v e l i s not believed to be a serious factor i n either salmon or herring mortality. More c o l l e c t i n g should be done offshore to determine the e f f e c t of fur seals upon ocean salmon. Halibut stocks on the B r i t i s h Columbia coast appear to be unaffected by pinniped predation. - 93 -LITERATURE CITED A b e g g l e n , C. E . , A. Y. R o p p e l and P. W i l k e . 1958. 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P r e c a r i o u s s t a t u s of the s e a l and sea l i o n on our no r t h w e s t c o a s t . J . Mammal., _°/: 10-l6? - 98 -S c h e f f e r , V. B. 1950. The f o o d o f t h e A l a s k a f u r s e a l . T r a n s . l £ t h N. Amer. W i l d . C o n f . , pp. 1L10-1L21. S c h e f f e r , V. B. 1958. S e a l s , s e a l i o n s and w a l r u s e s . S t a n -f o r d U n i v . P r e s s , S t a n f o r d . 179 PP* S c h e f f e r , V. B. and J . W. S l i p p . i9i4.iL. The h a r b o u r s e a l i n W a s h i n g t o n S t a t e . Amer. M i d i . N a t . , ^2: 373-l| 16. S c h e f f e r , V. B. and C. G. S p e r r y . 1931. Food h a b i t s o f t h e P a c i f i c h a r b o u r s e a l (Phoca v i t u l i n a ) . J . Mammal., 12: 2lli-226. S c h u l t z , L . P. and A. M. R a f n . 193°. Stomach c o n t e n t s o f f u r s e a l s t a k e n o f f t h e c o a s t o f W a s h i n g t o n . J . Mammal., 1 2(1): 13-15. S e r g e a n t , D. E . 1962. The b i o l o g y o f t h e p i l o t o r p o t h e a d whale, G l o b i c e p h a l a m e l a e n a ( T r a i l ) i n Ne w f o u n d l a n d w a t e r s . B u l l . P i s h . R e s . Bd. Canada, No. 132, 8k pp. S h e p a r d , M. P. and J . C. S t e v e n s o n . 1956. Abundance, d i s t r i -b u t i o n and c o m m e r c i a l e x p l o i t a t i o n o f t h e f i s h e r i e s r e s o u r c e of Canada's west c o a s t . 9th B. C. N a t u r a l R e s o u r c e s C o n f e r e n c e T r a n s a c t i o n s . S l e p t s o v , M. M. 1950. C o n c e r n i n g t h e b i o l o g y o f t h e f a r -e a s t e r n s ea l i o n . B u l l e t i n o f t h e P a c i f i c S c i e n t i f i c I n s t i t u t e o f F i s h e r i e s and Oce a n o g r a p h y , V i a d i v o s t o c k . V o l . 32 ( T r a n s l . by J . W. B r o o k s ) . S m i t h , N. M. 190li. R e p o r t on e n q u i r y r e s p e c t i n g f o o d f i s h e s , and f i s h i n g g r o u n d s . U. S. P i s h . Comm. R e p t . f o r 1902, pp. H l - 1 1 9 . S t a r k s , E . C. 1918. The sea l i o n s o f C a l i f o r n i a . Amer. Mus. J o u r n . , 18: 226-237. Sunde, L. A. and C. C. L i n d s e y . 1958. R e v i s e d k ey t o t h e r o c k f i s h e s ( S c o r p a e n i d a e ) o f B r i t i s h C o l u m b i a . Museum C o n t r i b u t i o n #1, I n s t , o f F i s h . , U n i v . o f B r . C o l . , Van-• c o u v e r . T a y l o r , P. H. C , M. P u j i n a g a , and P. W i l k e . 1955. D i s t r i -b u t i o n and f o o d h a b i t s o f t h e f u r s e a l s o f t h e N o r t h P a c i f i c Ocean. U. S. Dept. I n t e r i o r , F i s h and W i l d l i f e S e r v i c e , 10 86 pp. Templeman, W., H. J . S q u i r e s and A. M. F l e m i n g . 1957. Nema-t o d e s i n t h e f i l l e t s o f cod and o t h e r f i s h e s i n Newfound-l a n d n e i g h b o u r i n g a r e a s . J . F i s h . R e s . Bd. Canada, l k : T h o r s t e i n s o n , F. V. and C. J . L e n s i n k . 1962. B i o l o g i c a l o b s e r v a t i o n s of S t e l l e r s e a l i o n s t a k e n d u r i n g an e x p e r -i m e n t a l h a r v e s t . J . W i l d l i f e Management, ^ ( i j ) : 353-359. - 99 -T u r n e r , W. 1887. R e p o r t on t h e s e a l s . I n T r a n s p o r t a t i o n of r o c k p a r t i c l e s b y sea mammals, by K. 0. Emery, J . S e d i -m e n t a r y P e t r o l o g y , 11(2): 92-93. W i l k e , P. and K. W. Kenyon. 1952. N o t e s on t h e f o o d o f f u r s e a l s , s e a l i o n s and h a r b o u r p o r p o i s e . J . W i l d l i f e Management, 16(3)* 396. W i l k e , P. and K. W. Kenyon. 1954* M i g r a t i o n and f o o d of t h e n o r t h e r n f u r s e a l . T r a n s . 19th N. Amer. W i l d . C o n f . , pp. l4.3O-l4.l4_O. W o l l e b a e k , A. 1907. U b e r d i e B i o l o g i e d e r Seehunde und d i e S e e h u n d j a g e l i n e u r o p a e i s c h e n E i s m e e r h a u p t s a e c h l i c h n a c h N o r w e g i s c h e n Q u e l l e n . Rapp. Cons. E x p l o r . Mer., 8: 5-82. - 100 -APPENDIX 1: A q u a n t i t a t i v e estimate of the e f f e c t of sea l i o n s and harbour s e a l s on the B r i t i s h Columbia salmon and h e r r i n g f i s h e r i e s . E f f e c t i v e estimates of the amount of salmon and her-r i n g eaten by pinnipeds must be based on the f o l l o w i n g i n f o r -mation: (a) d a i l y food i n t a k e of each p r e d a t o r ; (b) numbers of p r e d a t o r s and how long they prey on each r e s p e c t i v e food item; (c) per cent c o n t r i b u t i o n of each prey to the t o t a l food Intake. In order to complete the c a l c u l a t i o n s below, the f o l -l owing procedure has been f o l l o w e d : (a) D a i l y food i n t a k e . T h i s ranges from 2% to 11$ of the body weight, w i t h a mean of 6$ (Table V). A l l c a l c u l a t i o n s are " based on 6$ of the body weight w i t h the p o s s i b l e range i n c l u d e d i n b r a c k e t s . (b) Numbers of pr e d a t o r s and d u r a t i o n of p r e d a t i o n . The h i g h e s t estimate of a p o p u l a t i o n s i z e has been used. P r e d a t i o n time i s based on how long the pr e d a t o r p o p u l a t i o n was i n the v i c i n i t y of i t s prey. (c) Per cent c o n t r i b u t i o n of each item. T h i s has been c a l c u -l a t e d on a per cent frequency of occurrence b a s i s , and has been taken from Table VI and VII and F i g u r e 13. The c a l c u l a t i o n s have been c a r r i e d out by m u l t i p l y i n g the d a i l y food i n t a k e (estimated from mean body weight) by the number of p r e d a t o r s , by the number of days of f e e d i n g , by the per cent c o n t r i b u t i o n of the p a r t i c u l a r food item. The- f o l l o w i n g c a l c u l a t i o n s are based on data which are o f t e n incomplete; f u r t h e r s t u d i e s may a l t e r these e s t i m a t e s . A. Sea l i o n s The mean f e m a l e sea l i o n w e i g h t i s 177 kg, or J4.50 l b ; a r e p r e s e n t a t i v e sample of males has not been weighed. However, as l a r g e a d u l t males f r e q u e n t l y weigh:.!,500 l b , the mean female weight has been do u b l e d t o a r r i v e a t a mean body weight of 900 l b f o r the t o t a l p o p u l a t i o n . 1. H e r r i n g The p o p u l a t i o n of IL,500 a n i m a l s ( e x c l u d i n g pups) w i l l r e q u i r e an e s t i m a t e d 87.5 (29.2-l60.li) m i l l i o n l b a n n u a l l y . H e r r i n g , f o r m i n g 10$ of t h i s ( F i g u r e 13) w i l l c o n t r i b u t e It,650 (1,550-8,500) t o n s . 2. Salmon Salmon c o n t r i b u t e 8$ t o the food i n t a k e of 3,100 sea l i o n s on the r o o k e r i e s f rom May 15 t o September 15 (Table V I I ) . D u r i n g t h e s e f o u r months an e s t i m a t e d 20.Ii (6-8-37-1+) m i l l i o n l b of f o o d are r e q u i r e d ; salmon would c o n t r i b u t e 1.6 (0.5-3*0) m i l l i o n l b . D u r i n g t h e e a r l y f a l l a p p r o x i m a t e l y o n e - h a l f , or 1,500 sea l i o n s l e a v e the r o o k e r i e s and move i n s h o r e t o j o i n the n o n - b r e e d i n g element of the p o p u l a t i o n . T h e r e f o r e , salmon forms 10$ of the d i e t of a p p r o x i m a t e l y 3,000 sea l i o n s d u r i n g October and November when the l a t e salmon r u n s a r e s t i l l a v a i l a b l e t o sea l i o n s . D u r i n g these two months 3,000 sea l i o n s r e q u i r e 9-7 (3-2-17.8) m i l l i o n l b of fo o d and salmon would c o n s t i t u t e 1.0 (0.3-1.8) m i l l i o n l b . Combining these two e s t i m a t e s of summer and f a l l c onsumption of salmon by sea l i o n s g i v e s a f i g u r e o f 2.6 (0.8-I4..8) m i l l i o n l b . - ro2-B. H a r b o u r s e a l s The mean body w e i g h t o f 23 h a r b o u r s e a l s was 100 l b . 1. H e r r i n g The e s t i m a t e d 20,000 h a r b o u r s e a l s a n n u a l l y r e q u i r e 1+3.2 (11+.1+-79.2) m i l l i o n l b o f f o o d . H e r r i n g f o r m i n g 12$ o f t h i s w o u l d c o n t r i b u t e 2,600 (8£0-l+,750) t o n s a n n u a l l y . 2. Salmon The numbers o f h a r b o u r s e a l s p r e y i n g on s a l m o n may be e s t i m a t e d by c a l c u l a t i n g t h e a v e r a g e number o f s e a l s p e r s a l m o n s p a w n i n g s t r e a m and m u l t i p l y i n g t h i s b y t h e t o t a l numbers o f s u c h r i v e r s and s t r e a m s on t h e c o a s t . T h e r e a r e a p p r o x i m a t e l y 900 s a l m o n s p a w n i n g c r e e k s e n t e r i n g s a l t w a t e r o r l a k e s a c c e s s i b l e t o s e a l s , e x c l u d i n g t h e Skeena R i v e r s y s t e m (Department o f F i s h e r i e s f i l e s ) . A n a v e r a g e o f f i v e t o t e n h a r b o u r s e a l s p e r c r e e k i s e s t i m a t e d f r o m my own o b s e r v a t i o n s , p l u s t h o s e o f f i s h e r i e s o f f i c e r s and o t h e r s w o r k i n g on salmon s t r e a m s . I f t e n s e a l s p e r c r e e k i s t a k e n as a maximum, 9,000 s e a l s may be r e g a r d e d as p o t e n t i a l p r e d a t o r s u pon s a l m o n i n t h e 900 s t r e a m s m e n t i o n e d above. F i s h e r (1952) e s t i m a t e d t h e r e were 1+00 s e a l s i n t h e l o w e r Skeena R i v e r , p l u s " s e v e r a l h u n d r e d " u p r i v e r . F o r t h e p u r p o s e o f t h e s e c a l c u l a t i o n s a t o t a l p o p u l a t i o n o f 1,000 s e a l s i n t h e Skeena R i v e r s y s t e m h a s been e s t i m a t e d . An a v e r a g e p r e d a t i o n p e r i o d of 70 days was c a l c u l a t e d f r o m t h e s e a s o n a l d u r a t i o n o f s a l m o n r u n s i n 37 s t r e a m s c h o s e n a t random (Department of F i s h e r i e s f i l e s ) . Runs o f s a l m o n o f a l l s p e c i e s l a s t e d an a v e r a g e o f 70 days i n e a c h s t r e a m . . . T h e r e f o r e , 10,000 s e a l s would r e q u i r e 1+.2 (I.I+-7.7) - io'a -m i l l i o n l b of food f o r 70 days. Salmon forming 30$ of th i s would constitute 1.3 (O.Ji-2.3) m i l l i o n l b . When these estimates are combined sea li o n s and harbour seals eat an estimated 7,250 (2,li00-13,250) tons of herring and li.O (1.2-7.1) m i l l i o n l b of salmon annually. The average annual herring catch i s 200,000 tons (Outram, 196l), and pinniped predation, therefore, may account f o r an amount equivalent to 1L$ (1.0-6.2$) of the annual catch. The average annual salmon catch i s 1I4.8 m i l l i o n lb and pinniped predation may account f o r an amount equivalent to 2.5$ (0.8-l4-.7$) of the annual commercial catch. - 104 -A p p e n d i x T a b l e I . S c i e n t i f i c a n d common names o f f o o d i t e m s m e n t i o n e d i n t e x t . I n v e r t e b r a t e s F. M o l l u s c a C. P e l e c y p o d a s h e l l f i s h Y o l d i a r n y a l i s M y t i l u s sp. M y t i l u s c a l i f o r n i a n u s c l a m m u s s e l m u s s e l C. C e p h a l o p o d a IS. O r d e r O c t o p o d a o c t o p u s P o l y p u s h o n g k o n g e n s i s  T r e m o c t o p u s sp. Loli,g;o o p a l e s c e n s  G o n a t u s magi s t e r  G. f a b r i c i i  G 6 n a t u s s p . G o n a t o p s i s sp. G. b o r e a l i s  O n y c h o t e u t h i s s p . 0. b a n k s i i  Ommastrepb.es s l o a n i  W a t a s e n i a ac i n t i l l a n s  D o s i d i c u s g i g a s  M o r o t e u t h i s l o n n b e r g i i  S t e n o t e u t h i s b a r t r a m i  C h i r o t e u t h i s v e r a n y i  A b r a l i o p s i s s p . 0. Decapoda U p o g e b i a p u g e t t e n s i s  C a l l i a n a s s a c a l i f o r n i e n s e  C a n c e r o r e g o n e n s i s C. m a g i s t e r C. g r a c i l i s S.' O r d e r Decapoda s q u i d P. A r t h r o p o d a C. C r u s t a c e a c r a y f i s h , l o b s t e r , s h r i m p , c r a b - 105 -H e m i g r a p s u a o r e g o n e n s i s  P a g u r u s sp. P e t r o t i s t h e s c i n c t i p e s P. e r i o m e r u s  P i n n i x i a s c h m i t t l G a r i d a e C r a g o f r a n c i s c o r u m G. s t y l i r o s t r i s  P a n d a l u s p l a t y c e r o s V e r t e b r a t e s C. C h o n d r i c h t h y e s F a m i l y P e t r o m y z o n t i d a e E n t o s p h e n u s t r i d e n t a t u s F a m i l y S q u a l i d a e S q u a l u s s u c k l e y i F a m i l y R a j i d a e R a j a s p . R. b i n o c u l a t a F a m i l y C h i m a e r i d a e H ydro l a g u s c o l l i e i F a m i l y P t e r o t h r i s s i d a e P t e r o t h r i s s u s g i s s u C . . O s t e i c h t h y e s F a m i l y C l u p e i d a e C l u p e a p a l l a s i i C. H a r e n g u s  A l o s a s a p i d i s s i m a  S a r d i n o p s m e l a n o s t i c t a F a m i l y E n g r a u l i d a e E n g r a u l i s mordax E . j a p o n i c a F a m i l y S a l m o n i d a e O n c o r h y n c h u s g o r b u s c h a 0. K i s u t c h 0. k e t a P a c i f i c l a m p r e y d o g f i s h s k a t e b i g s k a t e r a t f i s h g i s u h e r r i n g s ( c l u p e i d s ) P a c i f i c h e r r i n g A t l a n t i c h e r r i n g s h a d s a r d i n e a n c h o v y N o r t h e r n a n c h o v y s a l m o n p i n k salmon coho salmon chum s a l m o n - 106 -0, n e r k a 0. t s h a w y t s c h a  Salmo g a i r d n e r i  S a l v e l i n u s s p . F a m i l y Osmeridae' Hypomesus p r . e t i o s u s  M a l l o t u s T i l l o s u s  I h a l e i c h t h y s p a c i f i c u s = Osmerus mordax F a m i l y A r g e n t i n i d a e . B a t h y l a g u s s p . F a m i l y M e l a n o s t o m i a t . i d a e T a c t o s t o m a macropus F a m i l y M y c t o p h i d a e E l e c t r o n a s p . T a r l e t o n b e a n i a s p . T. c r e n u l a r i s L a m p a n y c t u s sp. L. n a n n o c h i r ' l a t i c f a u d a Myctophum c a l i f o r n i e n s e N o t o s c o p e l u s e l o n g a t u s F a m i l y S c o p e l a r c h i d a e S c o p e l o s a u r u s  S c o p e l a r c h u s l i n g u i d e n s F a m i l y P a r a l e p i d a e M a g n i s u d i s b a r y s o m a F a m i l y A n o t o p t e r i d a e A n o t o p t e r u s p h a r a o F a m i l y O p h i c n t h i d a e F a m i l y S c o m b e r e s o c i d a e C o l o l a b i s s a i r a F a m i l y A t h e r i n i d a e A t h e r i n i p s i s c a l i f o r n l e n s i s s o c k e y e s a l m o n s p r i n g salmon s t e e l h e a d t r o u t s m e l t s s u r f s m e l t c a p e l i n e u l a c h o n A m e r i c a n s m e l t b l a c k s m e l t a r r o w f i s h l a n t e r n f i s h b l u e l a n t e r n f i s h p e a r l e y e b a r r a c u d i n a s d a g g e r t o o t h snake e e l s P a c i f i c s a u r y j a c k s m e l t - 107 -F a m i l y E x o c o e t i d a e C y p s e l u r u s peduro F a m i l y M e r l u c e i i d a e M e r l u c e i u s p r o d u c t u s F a m i l y Gadidae T h e r a g r a chalcogrammus F o l l a c h i u s v i r e n s  Gadus macrocephalus G. morrhua G. ogae Melanogramtnus a e g l e f i n u s  L o t e l l a sp. M i c r o g a d u s proximus F a m i l y T r a c h y p t e r i d a e T r a c h y p t e r u s rexsalmonorum F a m i l y P l e u r o n e c t i d a e A t h e r e s t h e s s t o m i a s  H i p p o g l o s s u s s t e n o l e p i s  H i p p o g l o s s o i d e s e l a s s o d o n H. p l a t e s s o i d e s  G l y p t o c e p h a l u s c y n o g l o s s u s  L y o p s e t t a e x i l i s L. putnam L e p i d o p s e t t a b i l i n e a t a  P a r o p h r y s v e t u l u s  P l a t i c h t h y s s t e l l a t u s  P s e u d o p l e u r o n e c t e s americanus  O i t h a r i c h t h y s sp. F a m i l y E m b i o t o c i d a e Damalichthy's v a c c a  Cymatogaster a g g r e g a t u s F a m i l y T r i c h o d o n t i d a e T r i c h o d o n t r i c h o d o n F a m i l y Bramidae Brama r a i i F a m i l y S c o r p i d a e M e d i a l u n a c a l i f o r n i e n s i s P a c i f i c hake cods w h i t i n g ( w a l l e y e p o l l o c k ) p o l l o c k P a c i f i c cod A t l a n t i c cod G r e e n l a n d cod haddock P a c i f i c tomcod K i n g - o f - t h e - s a l m o n f l a t f i s h , f l o u n d e r a r r o w t o o t h f l o u n d e r P a c i f i c h a l i b u t f l a t h e a d s o l e p l a i c e w i t c h f l o u n d e r s l e n d e r s o l e smooth f l o u n d e r r o c k s o l e lemon s o l e s t a r r y f l o u n d e r w i n t e r f l o u n d e r f l o u n d e r ( s a n d dab) sea p e r c h e s s i l v e r p e r c h s h i n e r , sea p e r c h P a c i f i c s a n d f i s h pomfret halfmoon - 108 -F a m i l y G a r a n g i d a e = T r a c h u r u s s y m m e t r i c u s F a m i l y S c o m b r i d a e Scomber .japonicus P r o m e t h i c h t h y s p r o m e t h e u s T r a c h u r u s j a p o n i c u s F a m i l y T e t r a g o n u r i d a e T e t r a g o n u r u s c u v i e r i F a m i l y S p h y r a e n i d a e S p h y r a e i i a s p . F a m i l y A r i o p l o p o m a t i d a e Anoplopoma f i m b r i a F a m i l y Hexagrammidae Hexagrammos s p . P l e u r p g r animus r n o n o p t e r y g u i s P. a z o n u s O p h i o d o n e l o n g a t u s F a m i l y S c o r p a e n i d a e S e b a s t o d e s s p . 3 . f l a v i d u s S. p a u c i s p i n i s S. a l u t u s S. e n t o m e l a s S. .j o r d a n i S. r u b e r r i m u s  S e b a s t e s m a r i n u s F a m i l y C o t t i d a e S c o r p a e n i c h t h y s m a rmoratus F a m i l y G y c l o p t e r i d a e F a m i l y G a s t e r o s t e o i d e a G a s t e r o s t e u s a c u l e a t u s F a m i l y S y n g n a t h i d a e S y n g n a t h u s c a l i f o r n i e n s i s m a c k e r a l j a c k m a c k e r a l s m a c k e r a l ( P a c i f i c m a c k e r a l ) snake m a c k e r a l ( b l a c k t u n a ) h o r s e m a c k e r a l s q u a r e t a i l b a r r a c u d a s a b l e f i s h g r e e n l i n g A t k a m a c k e r a l ^ l i n g c o d r o c k f i s h y e l l o w r o c k f i s h B o c a c c i o o c e a n p e r c h widow p e r c h s h o r t b e l l y r o c k f i s h r e d s n a p p e r r e d f i s h s c u l p i n s m i d s h i p m a n l u m p s u c k e r s t h r e e s p i n e s t i c k l e b a c k k e l p p i p e f i s h - 109 -F a m i l y B a t h y m a s t e r i d a e B a t h y m a s t e r s i g n a t u s F a m i l y A n a r r h i c h a d i d a e F a m i l y S t i c h a e i d a e F a m i l y L a b r i d a e T a u t o g o l a b u s a d s p e r S U B F a m i l y Z o a r c i d a e F a m i l y A m m o d y t e s A m m o d y t e s h e x a p t e r u s F a m i l y B a t r a c h o i d i d a e P o r i c h t h y s n o t a t u s G l a s s A v e s . A e t h i a c r i s t a t e l l a  O c e a n o d r o m a h o m o c h r o a  F u l m a r u s g l a c i a l i s  X e m a s a b i n i P t y c h o r a m p h u s a l e u t i c u s  B r a e h y r a m p h u s m a r m o r a t u s  S y n t h l i b o r a m p h u s a n t i q u u s s e a r c h e r w o I f f i s h e s b l e n n i e s c u n n e r e e l p o u t s s a n d l a n c e ( l a u n c e J P m i d s h i p m a n ( s i n g i n g f i s h ) a s h y p e t r e l f u l m a r s a b i n e g i l l C a s s i n ' s a u k l e t m a r b l e d raurrelet a n c i e n t m u r r e l e t Appendix Table II. Pinniped stomach contents from'collections made in North American waters and the Western Pacific. Species of seal Authority- Month of collection and location *Number i n sample Identified food items (terminology of each author has been maintained) Northern fur seal Northern fur seal Northern fur seal Northern fur seal Northern fur seal Northern fur seal Northern fur seal Northern fur seal Taylor et a l . (1955) Anon. (1962) Alexander (1892) i n Taylor et a l . (1955) Lucas (1899) Schultz and Rafn (1936) May (1937) Bonham (1941) i n Taylor et a l . (1955) Western Pacific (February-June) Western Pacific (February-Oc tobe r) Gulf of Alaska Gulf of Alaska and Bering Sea (A p r i l -September) Washington (spring) Washington (spring) Washington (April) 1,138 Squid, herring, anchovy, salmon, lantern f i s h , saury, "hake", mackerel, snake mackerel, rock-fish , eel, birds. 3,769 Squid, gisu, sardine, anchovy, salmon, trout, pearleye, lan-tern f i s h , saury, Sphyraena sp., walleye pollock, Lotella sp., horse mackerel, Pacific mackerel, black tuna, Atka mackerel, Pleurogrammus azonus, Cyclopteridae, Cypselurus piduro, sandlance. 104 Squid, salmon, rockfish. 409 Squid, octopus, lamprey, salmon, black smelt, cod, whiting, rock-fish , cottid, wolf f i s h . 41 Shrimp, squid, lamprey, herring. 54 Squid, herring. Squid, shad. M H O Wilke and Kenyon (1954) West Crawfish Inlet (December-March) 148 Squid, herring, whiting. Species of seal Authority Month of collection *Number and location sample Northern Taylor et al. (1955) fur seal California, Oregon and Washington (February-April) 125 Northern Taylor et al. (1955) Alaska (June-July) fur seal . . 116 Northern Anon. (1962) fur seal California (December- 1,781 April) Northern Anon. (1962) fur seal Oregon (January-June) 93 Northern fur seal Anon. (1962) Washington (January-April) 480 Identified food items (terminology of each author has been maintained) Squid, lamprey, shad, Pacific herring, anchovy, salmon, surf smelt, jack smelt, eulachon, saury, hake, sand dab, sable-fish, rockfish, sandlance, bi rds. Squid, capelin, hake, sand-lance. Squid, octopus, dogfish, shad, herring, anchovy, salmon, surf smelt, eulachon, arrow fish, lantern fish, barracudines, saury, hake, king-of-the-salmon, flatfish, pomfret, halfmoon, jack mackerel, Pacific mackerel, black cod, rockfish, kelp pipe-fish, midshipman, birds. Squid, lamprey, shad, herring, salmon, eulachon, Scopelosaurus, lantern fish, saury, hake, king-of-the-salmon, flatfish, jack mackerel, blackcod, rockfish. Squid, lamprey, shad, herring, anchovy, salmon, surfsmelt, c capelin, eulachon, Osmeridae, lantern fish, saury,hake, whit-ing flatfish, sablefish, rock-fish, stickleback, sandlance. Species of seal Authority Month of collection *Number in and location sample Northern Anon. (1962) fur seal Alaska (February-June) 1,258 Northern Smith (1904) sea lion California (July-August) 13 Northern Starks (1918) sea lion California Northern Imler and Sarber (1947) Alaska (May-August) sea lio n . . . 15 Northern sea lion Kenyon and Wilke (1952) Alaska Northern Thorsteinson and Len- Alaska (summer) sea lio n sink (1962) 56 Northern Mathison et a l . (1962) Alaska (summer) 114 Identified food items (terminology of each author has been maintained) Squid, lamprey, herring, salmon, capelin, eulachon, Osmeridae, lantern fish, daggertooth, grey cod, tomcod, whiting, f l a t f i s h , Pacific sand f i s h , Atka mackerel, sablefish, Hexagrammidae, rock-fi s h , sculpins, Cyclopteridae, searcher, sandlance, birds. Crab, octopus, squid, skate, shark, clupeids, perch, cara-nagoid fis h , rockfish, hogfish. Squid, sardine, salmon, rockfish. Octopus, skate, salmon, tomcod, whiting, starry flounder, arrow-toothed halibut, halibut. Cephalopod beak, cod, pollock, flounder, halibut, starry flounder, sculpin, sandlance. Crab, clam, mussel, s n a i l , squid, octopus, f l a t f i s h , halibut, greenling, rockfish, cottids, sandlance, lumpfish. CoeLentenates, segmented worms, sand dollar, common bivalves, shrimp, crabs, isopods, unclas-s i f i e d crustaceans, lamprey, salmon, smelt, greenling, rock-fish, sculpin, sandlance. Identified food items Species A .+ Month of collection *Number in . ^ i Authority - 0,tT,r,1/=> (terminology of each author of seal and location sample . . . . has been maintained) California Smith (1904) sea lion California Starks (1918) sea li o n Harbour seal Harbour seal Harbour seal Harbour seal Harbour seal Fisher (1950) Fisher and Mackenzie (1955) Templeman et a l . (1957) Scheffer (1928); Scheffer and Sperry (1931) California (July- 13 August) California (July- 13 August) Atlantic coast of Canada Maritime Provinces (Jan- 201 uary-December) Newfoundland and Labrador Imler and Sarber (1947) Alaska (May-August) 96 Washington coast (U.S.A.) 95 (January-December) 166 Squid, ratfish, rockfish. Squid, fi s h . Squid, small f i s h (including sardines) Shrimp, squid, herring, shad, smelt, hake, cod, haddock, winter flounder, smooth flounder, unidentified f l a t -fish, rosefish, Gaspereau. Shellfish, clam, mussel, crab, lobster, shrimp, herring, salmon, trout, capelin, smelt, cod, Greenland cod, pollock, flounder, sculpin, launce, cunner, eel, eel-pout. Crabs, shrimps, crayfish, squid, octopus, lamprey, skate, ratfish, herring, salmon, hake, cod, tomcod, whiting, flounders, shiner, silver perch, lingcod, rock-fis h , sculpins, blenny, sand-lance, midshipman. Shrimp, octopus, skate, herring, salmonids, eulachon, cods, flounder, rockfish, sculpin, blenny. *Stomachs with food only 

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