Table 37. — Mean and standard deviations of the body lengths of male seals, 

 St. Paul Island, 17-26 July 1964-69 



Age and item 



Year measured 



1964 



1965 



Age 2: 



Number sampled . . 105 



Mean (cm.) 103.6 



Standard deviation . 4.93 



Percent s$ 104 cm. 1 60.9 



Age 3: 



Number sampled . . 1,233 



Mean (cm.) 112.7 



Standard deviation . 5.06 



Percent ^ 104 cm. 1 5.1 



Age 4: 



Number sampled . . 552 



Mean (cm.) 121.0 



Standard deviation . 6.48 



Percent ^ 104 cm. 1 0.5 



Age 5: 



Number sampled . . 79 



Mean (cm.) 128.0 



Standard deviation . 7.27 



Percent ^ 104 cm. 1 



1966 



1967 



1968 



1969 



1 The lower length limit of 104 cm. was removed during the sampling 

 period in 1964-68; there was no lower limits during the season in 1969. 



Organochlorine pesticides were found in the 

 tissues of all six sea lion pups and in all five 

 female sea lions taken on San Miguel Island 

 (table 40). 



Raymond E. Anas 



SUMMARY 



Field investigations on the Pribilof Islands 

 in 1969 were conducted from June to October 

 with the objective of adding to the fund of 

 knowledge needed to determine the level at 

 which the herd will produce a maximum sus- 

 tained yield. 



A kill of 38,678 males in ages 2 to 6 included 

 32,621 from St. Paul Island and 6,057 from 

 St. George Island; 230 females were killed 

 accidentally. 



In June, we counted 2,341 territorial males 

 with females and 7,935 without; 3 weeks later 

 in mid-July we counted 7,385 territorial males 

 with females and 3,212 without. Total counts 

 of adult males were 10,276 in June and 10,597 

 in July. 



The counts of dead seals on St. Paul and St. 

 George Islands included 14,810 pups of both 

 sexes and 116 males and 170 females older 

 than pups. 



The main causes of death among 208 pups 

 were malnutrition (27 percent), hookworm 

 disease (28 percent), and microbial infections 

 (12 percent). Other causes were trauma (6 

 percent) and perinatal complex (5 percent). 

 Miscellaneous and undetermined causes ac- 

 counted for 12 percent of the deaths, and 10 

 percent of the pups were unsuitable for exam- 

 ination. 



The average weight of living pups 28-29 

 August was 9.8 kg. for 400 males and 8.6 kg. 

 for 400 females. These weights were 0.3 kg. 

 more for males and 0.2 kg. more for females 

 than the average of weights of pups about 1 

 September for 1957-69. 



We marked 25,000 pups by removing the tip 

 of a digit on a hind flipper and applied a cry- 

 ogenic or "freeze" brand to the left forearm 

 of each of 775 pups. 



A total of 3,419 males known or believed to 

 be 1 and 2 years old were marked with tags. 



33 



