76 



U.S. BUREAU OF FISHERIES 



Distriution of pups on tlie Prihilof Islands, Aug. 10, 1932, and comparison 



ivith distribution in 1931 



Rookery 



1932 



Living 

 pups 



Dead 

 pups 



Total 

 pups 



Percent 

 dead pups 



Total 

 pups 



1932 



Increase 



St. Paul Island: 



Kitovi 



Lukanin 



Gorbatch 



Ardiguen 



Reef_.. 



Sivutch 



Lagoon (actual count) 



Tolstoi 



Zapadni 



Little Zapadni 



Zapadni Reef 



Polovina 



Polovina CliSs 



Little Polovina 



Morjovi 



Vostochni 



Total... 



St. George Island: 



North 



Staraya Artil 



Zapadni 



South 



East Reef... 



East Clififs 



Total.- 



Total (both islands). 



12,624 



6,060 



32, 250 



3,003 



64, 387 



19, 506 



109 



37, 930 



36, 330 



18, 372 



649 



13, 081 



7,139 



2,583 



4,666 



51, 903 



310, 592 



25, 418 

 18, 923 



2,710 

 632 



5,818 

 16, 614 



70, 115 



380, 707 



188 



134 



280 



74 



954 



488 



1 



535 



636 



471 



5 



203 



135 



1,103 



12,812 



6,194 



32, 530 



3,077 



65, 341 



19, 994 



110 



38, 465 



36, 966 



18, 843 



654 



13, 284 



7,274 



2,649 



4,762 



53, 006 



1.47 

 2.17 



.86 

 2.39 

 1.46 

 2.44 



.91 

 1.39 

 1.72 

 2.50 



.80 

 1.53 

 1.85 

 2.51 

 2.02 

 2.08 



11, 863 



5,735 



30, 120 



2,849 



60, 501 



18, 513 



114 



35, 616 



34, 228 



17, 447 



606 



12, 300 



6,735 



2,453 



4,409 



49, 080 



5,369 



315, 961 



1.70 



292, 569 



361 



501 



31 



11 



25, 779 

 19, 424 



2,741 

 643 



5,907 

 16, 865 



1.40 

 2.58 

 1.12 

 1.72 

 1.51 

 L49 



23, 869 

 17, 985 



2,538 

 595 



5,470 

 15, 616 



1,244 



71, 359 



1.74 



66, 073 



6,613 



387, 320 



358, 642 



459 



2,410 



228 



4,840 



1,481 



-4 



2,849 



2,738 



1,396 



48 



984 



539 



196 



353 



3,926 



23, 392 



1,910 

 1,439 



203 

 48 



437 

 1,249 



5,286 



28, 678 



MORTALITY OF SEALS AT SEA 



Very little is known as to the cause of the high mortality rate of 

 seals at sea during the first 3 years of life. The greatest loss prob- 

 ably occurs soon after the pups leave the islands in the late fall. 

 Up to that time the pups have been well cared for by the cows, but 

 upon leaving the islands they must learn to shift for themselves — • 

 catch their own food and avoid their natural enemies. During this 

 precarious period of their existence a great many undoubtedly die, 

 especially if food happens to be scarce and enemies abundant. On 

 the other hand, when food is plentiful and there are few natural 

 enemies the mortality rate would be considerably lower. As the 

 fluctuations resulting from such extreme conditions tend to offset 

 each other over a period of years, it is believed that the large increase 

 in the number of 3-year-olds available for killing during recent years 

 was primarily the result of leaving a larger breeding reserve, rather 

 than to any marked decrease in the mortality rate. 



COMPLETE COMPUTATION 



The following summary shows the methods used for computing 

 the number of animals in the Pribilof Islands fur-seal herd in 1932. 

 The total number of seals of all classes is 1,219,9G1, or 92,879 more 

 than were in the herd in 1931. This is an increase of 8.24 percent, 

 as compared with an increase of 7.84 percent in 1931 over the 

 preceding year. 



