ALASKA FISHERY AND FUR-SEAL INDUSTRIES, 1930 



105 



make pup counts of the smaller rookeries only. It is also a well- 

 known fact that densely populated rookeries increase fastei than those 

 sparsely populated and that the rookery or island on which a seal is 

 born has no bearing on the place it may haul out thereafter. It is 

 also true that the rate of increase varies considerably from year to 

 year, so the average rate of increase must be based on the total 

 increase over a term of years. 



The number of dead pups can also only be estimated, and the per- 

 centage found in the count of 1922 therefore has been applied to each 

 rookery. For comparative purposes it is necessary to include the 

 estimated number of dead pups in the total number of pups. 



By inference, the number of cows is the same as the number of 

 pups, as a female seal gives bu*th to but one pup each year. 



On Polovina rookery there was observed a cow bearing a brand of 

 the 1912 series. In that year some 5,000 pups, male and female, 

 had been marked with a hot iron shaped like the letter T and applied 

 to the top of the head. 



Distribution of pups on the Pribilof Islands, August 10, 1930, and comparison 



with distribution in 1929 



Rookery 



St. Paul Island: 



Kitovi 



Lukanin 



Gorbatch 



ArdiiTuen 



Reef 



Sivutch 



Lagoon (actual count) 



Tolstoi 



Zapadni 



Little Zapadni 



Zapadni Reef 



Polovina 



Polovina Cliffs 



Little Polovina 



Morjovi _ 



Vostochni.. 



Total. 



St. Georpe Island: 



North 



Staraya Artil 



Zapadni 



SoTith. 



East Reef 



East Cliffs 



Total... 



Total (both islands) 



Living 

 pups 



10, 823 



5,195 



27, 649 



2, 575 



55, 202 



16, 724 



113 



32, 520 



31,148 



15, 751 



557 



11,215 



6,121 



2.214 



4,000 



44, 499 



266, 306 



21, 792 

 16, 223 



2,324 

 542 



4,989 

 14, 244 



60, 114 



326, 420 



Dead 

 pups 



161 

 115 

 240 

 63 



818 

 418 



458 



545 



404 



4 



174 



115 



57 



82 



945 



4,599 



309 

 430 



26 

 9 



76 

 215 



1,065 



5,664 



Total 

 pups 



10,984 



5, 310 



27, 889 



2,638 



56, 020 



17, 142 



113 



32, 978 



31, 693 



16, 155 



561 



11, .389 



6,238 



2,271 



4,082 



45, 444 



270, 905 



22, 101 

 16, 653 



2,350 

 .551 



5, 005 

 14,459 



61, 179 



332, 084 



Per cent 

 dead pups 



1.47 

 2.17 

 .86 

 2.39 

 1.46 

 2.44 



1.39 

 1.72 

 2.50 

 .80 

 1.53 

 1.85 

 2.51 

 2.02 

 2.08 



1.70 



1.40 

 2.58 

 1.12 

 1.72 

 1.51 

 1.49 



1.74 



Total 

 pups 



10,170 



4,917 



25, 823 



2, 443 

 51, 870 

 15, 872 



112 

 30, 535 

 29, 345 

 14, 95S 

 519 

 10, 545 

 5, 774 

 2,103 



3, 780 

 42, 078 



250, 844 



20, 461 

 15,419 



2,176 

 510 



4, 690 

 13, 388 



56, 647 



307, 491 



1930 



Increase 



814 



393 



2,066 



195 



4,150 



1,270 



1 



2,443 



2, 348 



1,197 



42 



844 



462 



168 



302 



3,366 



20, 061 



1,637 

 1,234 



174 

 41 



375 

 1,071 



4, 532 



24, 593 



MORTALITY OF SEALS AT SEA 



The mortaUty rates used this season for computing the number of 

 seals in the herd, are the same as used in the estimate for 1929. The 

 mortality at sea varies considerably from year to year. The per- 

 centages of loss or natural death rates as used in this season 's compu- 

 tation will answer all practical purposes until abnormal conditions 

 are noted. 



