182 U. S. BUREAU OF FISHERIES 
Distribution of pups on the Pribilof Islands, Aug. 10, 1939, and comparison with 
distribution in 1938 













1939 ee 
ota 
Rookery we pups, Tcres se 
Living Dead Total pups Percent 1938 
pups pups PUPS | dead pups 
St. Paul Island: 
IKGEEO VIR oe eee eee 21, 6383 323 21, $56 1.47 20, 330 1, 626 
ukanin- 22 eee 10, 385 230 10, 615 20Le. 9, 829 786 
Gorbateh? 222) a ee ee 55, 271 479 55, 750 86 51, 620 4, 130 
Ardiguen= 2-22) ies 5, 148 126 5, 274 2.39 4, 883 391 
Reel ea eee SE ees 110, 348 1, 635 111, 983 1. 46 103, 688 8, 295 
Siviut che eke eee anne 33, 431 836 34, 267 2. 44 31, 729 2, 538 
Lagoon (actual count) -------_-- 32) ob ee B2)\<s2sesesnei8 53 —21 
TROIS EOL ts ene ea tee eee ae eee 65, 004 916 65, 920 1.39 61, 037 4, 883 
Aapadni ys aes eee Ee 62, 262 1, 090 63, 352 | 1.72 58, 659 4, 693 
Whittle Zapadnive seers wee 31, 486 807 32, 293 2. 50 29, 901 2, 392 
ZapadnipRect esses ese a 1, 111 9 1, 120 . 80 1, 037 83 
Poloving- eee a es 22, 421 348 22, 769 1.53 21, 082 1, 687 
iPolovina Clifisees ess ar 12, 235 231 12, 466 1.85 11, 543 923 
ittle Polovinas == 4, 425 114 4, 539 2. 51 4, 203 336 
MOOV See eee eee 7, 995 165 8, 160 2. 02 7, 556 604 
WoOstochniassstees etree: a ten ee 88, 953 1, 890 90, 843 2. 08 84, 114 6, 729 
Tota Ses ae ae ee ee ee 532, 140 9, 199 541, 339 1.70 | 6501, 264 40, 075 
St. George Island: 1 
0) 8 aes ey en gh 43, 561 619 44, 180 1, 40 40, 907 3, 273 
StarayarAriiioy so eu tee 32, 429 859 33, 288 2. 58 30, 822 2, 466 
DEVO b aN eae ss eo ae 4, 644 53 4, 697 2 4, 349 348 
South_____ 1, 084 19 1, 103 ilaih 1, 021 82 
East Reef_ 9, 970 153 10, 123 1.51-} 9, 373 750 
East Cliffs 28, 473 431 28, 904 1.49 26, 763 2, 141 
Total: 2 Sew sae ae PE 120, 161 2, 134 122, 295 1.74 113, 235 9, 060 
Total (both islands) -__.______ 652, 301 11, 333 663, 634 LEZ AL 614, 499 49, 135 
| 




MORTALITY OF SEALS AT SEA 
The number of killable 3-year-old male seals arriving at the islands 
this season indicated that it would not be desirable this year to change 
the mortality rates for any of the age classes. The sharp decrease in 
the number of harem bulls makes it appear that possibly there was 
a considerably greater mortality among the seals during one or several 
years of the life cycle of the males which should now be in the breeding 
bull classes. This increased death rate, if such there were, may now 
be leveled off by a correspondingly smaller death rate for the present 
and following 3-year-old classes. 
Continually changing conditions at sea, causing a considerable 
increase or decrease in the death rate from year to year, make it 
entirely impossible to establish a constant mortality rate. Continuous 
abnormal conditions make it possible to know only after a number of 
years have elapsed whether mortality rates have been incorrect for a 
given period. 
COMPLETE COMPUTATION 
The following summary shows the methods used in computing the 
number of animals in the fur-seal herd of the Pribilof Islands in 1939. 
The total number of seals of all classes as of August 10, 1939, was 
2,020,774, or 148,336 more than in 1938. This gives an increase for 
the herd of 7.92 percent. 
