MORTALITY 



In recent years, counts of dead pups on 

 land have varied from 119,505 in 1956, to 

 37,740 in 1958, to 74,702 in I960 and, finally, 

 to 39,239 in 1963. Mortality of pups on land, 

 although considerable, is much less than that 

 which occurs at sea. 



Wide fluctuations in the annual male kill are 

 the result of variation in ocean mortality. 

 Therefore, a basis for predicting ocean 

 mortality must be established if accurate 

 forecasts of the kill are to be made. 



As an approach to this problem, a veteri- 

 narian was added to the staff of the Marine 

 Mammal Biological Laboratory in 1962 to in- 

 vestigate causes of mortality on land and to 

 determine if some land-originated factor or 



factors can be linked to ocean mortality. If 

 such factors exist, their identification and 

 a means of measuring their influence on ocean 

 survival would be a valuable contribution 

 toward an understanding of the population 

 dynamics of fur seals. 



Veterinary studies in 1963 included pathology, 

 bacteriology, parasitology, nutritional re- 

 quirements of pups, and anatomy and physiology 

 of the fur seal. A separate report will be made 

 on these studies. 



Total Dead-Pup Counts 



Pup mortality in 1963 decreased by 28 per- 

 cent of the 1962 count on St. Paul Island and 

 by 19 percent on St. George Island (table 27). 

 The 1963 level is only slightly above that of 

 1958, the lowest year since the beginning of 

 complete dead-pup counts in 1953. Dead-pup 

 counts made since 1941 are presented in 

 appendix table 15. 



A record of tagged pups found dead on 

 Pacific coast beaches since 1948 is given in 

 table 28. The data, however, are not usable 

 for estimating ocean mortality because the 

 sample is small and there is no certainty 

 that recovery effort and the rate that seals 

 wash ashore are consistent each year. 



Table 28. — Tag recoveries from dead 

 pups or yearlings reported by the 

 public along the Pacific coast, 

 1948-63 



Dead-Pup Counts on Sample Areas 



Counts of dead pups on the sample areas 

 were continued in 1963 as a part of the annual 

 dead-pup counts (tables 29 and 30). 



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