Table l. — Comparative frequency of major prey identified in stomach contents and feces from 351 harbor seals 

 collected in the Gulf of Alaska. Prey are ranked in descending order of occurrence. Comparisons of proportion of 

 occurrence of prey found in stomach contents and feces were made by contingency table analysis when samples 

 were adequate (minimum cell size &5). 



•p<o.oi. 



'Others included unidentified prey and minor prey (those with 



5 occurrences in both stomach contents and feces). 



Salmon, Oncorhynchus spp., remains were iden- 

 tified in four stomachs while none were found in 

 the fecal samples. I have examined nine harbor 

 seal stomachs containing salmon remains and 

 only one included a head with otoliths. It appeared 

 that seals often fragmented large fish such as 

 salmon while eating them, usually discarding the 

 head. Thus, studies of feeding habits based on scat 

 analyses (which require the presence of otoliths) 

 probably underrepresent utilization of large fishes 

 such as salmon. One occurrence of a cartilaginous 

 fish was encountered (listed under others in Table 

 1). This was a skate, Raja sp., found in a stomach. 

 It is unlikely that cartilaginous fishes would be 

 detected in scats, as they have tiny, diffuse 

 otoliths. (Lagler et al. 1962). 



In summary, it appears that analysis of scats 

 from harbor seals can provide accurate informa- 

 tion on utilization of most kinds of prey. However, 

 cephalopods, cartilaginous fishes, and large fishes 

 such as salmon may be underrepresented. 

 Cephalopod remains may be overrepresented in 

 stomach contents. 



Acknowledgments 



This work was supported by the Alaska De- 

 partment of Fish and Game and the Marine 

 Mammal Commission and by the Bureau of Land 

 Management through an interagency agreement 

 with the National Oceanic and Atmospheric Ad- 



ministration, under which a multiyear program 

 responding to needs of petroleum development of 

 the Alaskan continental shelf is managed by the 

 Outer Continental Shelf Environmental Assess- 

 ment Program office. The suggestion to compare 

 results of the two methods of analysis was made by 

 F. Fay. Field assistance was provided by many 

 members of the Alaska Department of Fish and 

 Game. Thanks are due to D. Calkins, F. Fay, K. 

 Frost, L. Lowry, D. McKnight, K. Schneider, and 

 two anonymous reviewers for commenting on the 

 manuscript. 



Literature Cited 



FISCUS, C. H., AND G. A. BAINES. 



1966. Food and feeding behavior of Steller and California 

 sea lions. J. Mammal. 47:195-200. 

 IMLER, R. H., AND H. R. SARBER. 



1947. Harbor seals and sea lions in Alaska. U.S. Fish 

 Wildl. Ser\'., Spec. Sci. Rep. 28, 23 p. 

 Lagler, K. E, J. E. Bardach, and R. R. Miller. 



1962. Ichthyology Wiley N.Y, 545 p. 



Spalding, D. J. 



1964. Comparative feeding habits of the fur seal, sea lion 

 and harbor seal on the British Columbia coast. Fish. 

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Kenneth W. pitcher 



Alaska Department of Fish and Game 

 333 Raspberry Road 

 Anchorage, AK 99502 



798 



