110 ALASKA FISHERIES AND FUR INDUSTRIES IN 1919. 



Increase or Decrease in Number of Pups in 1919 from 1918. 



Rookery. 



ST. PAUL ISLAND. 



Kitovi 



Lukanin , 



Gorhat ch 



Ardiguen 



Reef 



Sivutch 



Lagoon 



Tolstoi 



Zapadni 



Little Zapadni 



Zapadni Keef 



Polovina 



Polovina Clills 



Little Polovina 



Morjovi 



Vost ochni , 



Total 



ST. GEOKGE ISLAND. 



North 



Staraya Artil 



Zapadni , 



South , 



East Reef 



East Clifls 



Total 



Total, both islands 



Total 

 pups, 

 1918. 



2,540 



2,235 



9,486 



792 



19, 39S 



6,325 



512 



16, 725 



11,460 

 9,089 

 536 

 5,343 

 1,882 

 1,491 

 3,335 



31, 468 



122,617 



7,011 

 5,440 

 806 

 61 

 2,120 

 4,860 



20, 298 



Total 

 pups, 

 1919. 



3,565 



2,7S8 



12, .308 



1,150 



22, 457 



7,015 



445 



16, 027 



14,300 



10, 145 



604 



5,794 



2,209 



1,203 



3,041 



30,863 



133,914 



8,802 

 5,746 

 857 

 68 

 2,367 

 5,418 



23, 258 



142,915 157,172 



Numer- 

 ical 

 increase. 



1,025 



553 



2,822 



358 



3,059 



690 



- 67 



-698 



2,840 



1,056 



68 



451 



327 



-288 



-294 



-605 



11,297 



1,791 



306 



51 



7 



247 



558 



2,960 



14,257 



Increase 



(+)or 



decrease 



Per cent. 

 +40. 35 

 +24. 74 

 +29.74 

 +45. 20 

 + 15.76 

 + 10.90 

 -13.08 



- 4.17 

 +24. 78 

 + 11.61 

 + 12.68 

 + 8.44 

 + 17.37 

 -19.31 



- 8.81 



- 1.92 



+ 9.21 



+25.54 

 + 5.62 

 + 6.32 

 + 11.47 

 + 11.65 

 + 11.48 



+ 14.58 



+9.97 



A casual inspection of the foregoing table discloses a great varia- 

 tion in the growth of the various rookeries. It ranges from a loss of 

 19.31 per cent in one case to a gain of 45.20 per cent in another. 

 Some of this variation might be attributed to the defects in the 

 method of arriving at the number of pups on rookeries not actually 

 counted, but it can not explain it all. A constant rate of increase 

 simply is not a phase of rookery development, and this is the greatest 

 objection to the use of a single breeding area as a type in census cal- 

 culations. 



COWS. 



NUMBER. 



The number of breeding cows is by inference the same as the num- 

 ber of pups, since but a single young is born annually. Although a 

 birth of twins is unknown in the species, it is not believed to be entirely 

 impossible from an anatomical standpoint and may on very rare 

 occasions occur. 



The figures for the pups show that there has been an increase of 

 cows of 9.97 per cent from 1918. This figure is to be compared with 

 11.63 percent for 1918. 



The figures show that the average annual increase is between 9 

 and 10 per cent under present conditions. This is an exceedingly 

 slow rate of growth for animals which live as long and breed as often 

 as fur seals. It emphasizes the enormous loss the species suffers 

 annually from some enemy of which we know practically nothing. 

 It now seems certain that 50 per cent of all animals born are lost 



