T r 



27 29 I 



16 18 20 22 



JUNE JULY 



DATE 



AUGUST 



Figure 11. — Pup mortality onReef Rookery study area, and weather on St. Paul Island, 27 June to 22 August 1966. 



An increase in mortality of pups after 

 stormy weather on the Pribilof Islands has 

 been reported. ■•- Data associating weather and 

 mortality of pups in 1964 and 1966 (figs. 10 and 

 11) also show an increase in the number of 

 deaths following rains. It is not known whether 

 storms appreciably increase mortality or 

 create focal points for deaths that would occur 

 anyway. 



Adults 



In 1965, dead adult males found on the 

 rookeries and all other beaches on St. Paul 

 Island were counted, and upper canine teeth 

 still in the skulls were collected for deter- 

 mining age. This program was expanded in 

 1966 to include dead adult females on St. Paul 

 Island and dead adults of both sexes on St. 

 George Island. The ages of males found dead 

 on St. Paul Island in 1965 have been used in a 

 study of adult males (see special studies 

 section of this report). 



iCarl E. Abegglen, Alton Y. Roppel, and Ford Wilke. 

 1957. Alaska fur seal investigations, Pribilof Islands, 

 Alaska, report of field activities, June-October 1957. 

 Bureau of Commercial Fisheries Marine Mammal Bio- 

 logical Laboratory, Seattle, Wash. [Manuscript report.] 



We counted 158 dead adult males in 1965 

 and 181 in 1966 on St. Paul Island, and 41 on 

 St, George Island in 1966. 



In 1966 we counted 55 dead adult females 

 on St. George Island and 172 onSt, Paul Island. 



COUNTS OF LIVING ADULT MALES 



Harem and idle males have been counted 

 about mid-July nearly every year on the 

 Pribilof Islands since 1911; natural and arti- 

 ficial markers on the rookeries have been 

 used as section boundaries for aids in counting. 

 Boundaries were changed from time to time; 

 in recent years, the number of harem males 

 in the various sections has ranged from 2 to 

 over 200. Before counting the adult males on 

 St. Paul Island in 1966, we placed markers 

 (marine plywood 1.9 by 40.6 by 40.6 cm. (3/4 

 by 16 by 16 inches) with orange numerals on 

 a white background) on each rookery, spaced 

 so that the area between successive markers 

 contained about 100 harem males, (Counts 

 obtained in 1965 were used as a basis 

 for placing the markers.) Numbered sections 

 facilitate counting and will be useful for making 

 detailed comparisons of the populations of 

 harem and idle males from year to year. 



The total number of adult males counted on 

 the Pribilof Islands in mid-July decreased for 



12 



