Pelagic research was conducted off central and southern California from 21 

 January to 25 March 1966. Seal distribution was studied along transects extending 

 19 to 222 km. offshore between lat. 32° N. and 38° N. at 37-km. intervals. Seals 

 were usually found 37 to 130 km. offshore. The largest concentrations of seals were 

 usually near areas where abrupt changes in depths occur along the Continental Shelf 

 and over seavalleys and seamounts. 



Of 2,704 seals sighted, 444 were collected, 78 were wounded and lost, and 67 

 sank after they were killed. Males formed only a small part of the population. Of 

 428 females taken, 52 percent were gravid; the youngest gravid female was a 

 primiparous 4-year-old. 



A lanternfish ( Myctophum californiense ), a sciaenid (species unknown), and a 

 squid ( Chiroteuthis veranyi ) were found in fur seal stomachs for the first time. 

 Northern anchovy ( Engraulis mordax ). Pacific saury ( Cololabis saira). Pacific 

 hake ( Merluccius productus ). and squids were the principal food species of fur 

 seals off California. 



INTRODUCTION 



Annually the Bureau of Commercial Fish- 

 eries reports on its fur seal investigations on 

 the Pribilof Islands and at sea. Investigations 

 on the islands are directed mainly toward the 

 developnnent of a rational system for holding 

 the seal population at the level of maximum 

 productivity. At sea, the primary motivations 

 for research are the problems of fur seal 

 predation on commercially important fishes 

 and the intermingling of seals from the eastern 

 and western Pacific Ocean. It is unlikely that 

 unequivocal conclusions can be reached soon 

 on either problem. General understanding of 

 the pelagic life of fur seals, however, has 

 been greatly improved during the past 9 years 

 of research. 



The object of this report is to provide re- 

 sults of research by the United States in 1966. 

 The North Pacific Fur Seal Commission has 

 recommended that each member Government 

 make such a report. 



A summary of the research data collected 

 on the Pribilof Islands in 1966 is given in 

 Part I of the following report. Contributors 

 were Raymond E. Anas, Douglas G. Chapman 

 (Laboratory of Statistical Research, University 

 of Washington), Ancel M. Johnson, Mark C. 

 Keyes, Alton Y. Roppel, Victor B. Scheffer, 

 and Ford Wilke (appendix B). A description of 

 investigations of fur seals at sea off Cali- 

 fornia is given in Part II. Contributors were 

 Clifford H. Fiscus and Hiroshi Kajimura, 



Part I. FUR SEAL INVESTIGATIONS, PRIBILOF ISLANDS, ALASKA 



The two interdependent major efforts of fur 

 seal research have been to improve population 

 estimates and find the level of maximum yield. 

 No recorded experience allowed a timetable to 

 be prepared for this study of the population of 

 an animal that lives as long as 30 years. 



Since 1954 we have been refining estimates 

 of the number of fur seals in the Pribilof 

 Islands population, and since 1956 we have 

 reduced the population in an attempt to bring 

 it near the level of maximum sustainable 

 yield. By 1965, progress in achieving the two 

 main objectives had reached the point where 

 we could manage the seal resource and con- 

 tinue population research with greater con- 

 fidence. 



From 1955 to 1962, 50,000 to 60,000 pups 

 were tagged yearly to provide a basis for 

 population estimates and to make possible a 

 study of the intermingling of seals from the 

 eastern and western Pacific Ocean. We found, 

 however, that population estimates based on 

 the recovery of seals tagged as pups in those 

 years were inflated. Since 1963, the number 

 of pups tagged was reduced first to 25,000 

 and then to 12,500. Now we are also tagging 

 about 3,000 yearling and older seals to obtain 

 information on mortality between age groups 

 within each year class. 



At the present population level, seal pup 

 mortality on land has declined to between one - 

 third and one-half of the high losses of the 



