Fur Seal Investigations, 1969 



By 



National Marine Fisheries Service 1 



MARINE MAMMAL BIOLOGICAL LABORATORY 



Naval Support Activity 



Seattle, Washington 98115 



ABSTRACT 



Field investigations of the fur seal, Callorhinus ursinus, in 1969 were conducted 

 on the Pribilof Islands from June to October and in the eastern North Pacific Ocean, 

 off the State of Washington, in February and March. 



The kill included 38,678 males and 230 females. 



We counted 10,276 living adult males in June and 10,597 in July. 



Dead fur seals counted included 14,810 pups and 286 animals older than pups. 



The main causes of death among 208 pups were malnutrition, hookworm disease, 

 and microbial infections. 



The average weights of pups in late August were 9.8 kg. for males and 8.6 kg. 

 for females. 



We marked 25,775 pups of both sexes and 3,419 male seals presumed to be ages 

 1 and 2, and recovered 3,558 marked male seals. 



Tag loss varies with tag series. Data on the relative effectiveness of two kinds 

 of marks used on fur seals are inconclusive. 



Estimates of the number of pups born in 1966 were 461,000 from tagging and 

 390,000 from shearing and sampling. According to sheared to unsheared ratios, an 

 estimated 303,500 pups were born in 1969. 



The forecasted kill of males in ages 2 to 5 in 1970 is 53,700. The predicted 

 kill of males in ages 2 to 5 in 1969 was 56,500 ; the actual kill was 38,440. 



About 68 percent of 334 young males tagged on St. Paul Island in 1968 and 69 

 percent of 555 tagged there in 1969 have since been recovered on the Pribilof Islands. 

 Four of eleven transmitters attached to young males were unaccounted for at the 

 end of the season in 1969. 



Weights of the bacula of young males ranged from 3 to 11 dg. at age 2 to 13 

 to 45 dg. at age 5, and weights of the testes ranged from 9 to 18 g. at age 2 to 23 

 to 99 g. at age 5. 



The number of females collected at sea in 1968 were too few to permit a com- 

 parison of body lengths and reproductive conditions between animals on St. Paul 

 Island and at sea during comparable periods. 



Organochlorine pesticides were found in the tissues of fur seals, sea lions, and 

 marine birds. 



1 Formerly the U.S. Department of the Interior, Fish 

 and Wildlife Service, Bureau of Commercial Fisheries. 



