With international cooperation the northern 

 fur seal population lends itself far better than 

 most other animal populations to studies of 

 population dynamics and to management. The 

 continuing investigations have provided much 

 of the information needed to manipulate the 

 seal population. Much less progress has been 

 made on the more difficult problem of under- 

 standing the relationship of factors affecting 

 the population and the effect of population 

 density. 



This report describes research done by the 

 United States in 1967 on land and at sea, as 



approved by the North Pacific Fur Seal Com- 

 mission at its 10th annual meeting in February 

 1967. 



Part I, on land investigations, was con- 

 tributed by the following: Raymond E. Anas, 

 Douglas G. Chapman (Laboratory of Statistical 

 Research, University of Washington), Ancel M. 

 Johnson, Mark C. Keyes, Alton Y. Roppel, and 

 Ford Wilke. 



Part II, on pelagic investigations, is a sum- 

 mary of work done by Clifford H. Fiscus, 

 Hiroshi Kajimura, and Richard K. Stroud. 



Part I. FUR SEAL INVESTIGATIONS, PRIBILOF ISLANDS, ALASKA 



The objectives of fur seal research on the 

 Pribilof Islands are to (1) collect the data 

 needed to determine the reaction of the herd 

 to an artificially low population level created 

 to provide a basis for determining the level of 

 maximum sustained yield, (2) determine the 

 causes of mortality, and (3) find a way to ac- 

 curately predict survival of the young to ages 3 

 and 4. This report summarizes the information 



collected in 1967 and describes the progress 

 made toward the achievement of these objec- 

 tives. 



Terms having special meanings in fur seal 

 research are described in the Glossary. Fig- 

 ures 1 and 2 show the location of rookeries 

 and hauling grounds on St. Paul and St. George 

 Islands. 



AGE CLASSIFICATION AND NUMBER OF SEALS KILLED, BY SEX 



The kill of seals on St. Paul and St. George 

 Islands in 1967 was 54,891 males (ages 2 to 6) 

 and 10,096 females (age 2 and older). 



MALES 



A kill of 54,891 males in ages 2 to 6 included 

 42,359 taken on St. Paul Island and 12,5 32 

 taken on St. George Island (tables A-l toA-4). 

 An additional 829 young males of unknown ages 

 were inadvertently taken during the kill of 

 females 7-17 August. 



The kill of males in 1967 was adjusted ac- 

 cording to methods described previously (U. S. 

 Fish and Wildlife Service, Bureau of Com- 

 mercial Fisheries, 1969) to show the magni. 

 tude of possible error in determining ages 

 from canine teeth (table 1). We did not use the 

 corrected ages in calculations involving the 

 age classification of the kill in 1967 because 

 we have not tested possible errors in deter- 

 mining ages both between days within years 

 and between years. In any case, errors in 

 determining age are small and would have 

 little effect on the numbers of seals in each 

 age except for those taken at age 2. 



All available subadult males 107 cm. (42 

 inches) long or longer from tip of nose to tip 

 of tail, but without manes, were taken. Three- 

 year-olds dominated the kill throughout the 

 season on St. Paul Island (fig. 3) and after 

 6 July on St. George Island (fig. 4). Efforts 

 were continued to increase the utilization of 



males by killing as many as practical of the 

 large 4-year-olds and by using firecrackers to 

 frighten seals away from inaccessible reefs 

 and from under cliffs. 



The lower length limit of 107 cm. (42 inches) 

 was removed on St. Paul Island during the kill 

 on Northeast Point Rookery 22 July and on 

 Zapadni Rookery 24 July so that all available 

 2-year-old males could be killed for our 

 study of the relation of abundance on land at 

 age 2 to the number available for killing 

 at age 3. We determined age and body length 

 for 20 percent of all males killed on these 2 

 days. 



Male seals were killed Monday through 

 Saturday of each week on St. Paul Island, and 

 on Mondays, Wednesdays, and Fridays on St. 



Table 1. — Unadjusted and adjusted kill of male seals, 

 Pribilof Islands, Alaska, 1967 



