222 



Answer. Because we have no additional criteria on which to base a calcula- 

 tion for optimum poinilation, we assume optimum population is the same as 

 the level for maximum sustainable yield (MSY). Maximum sustainable yield 

 is estimated from a populati<.n producing 400,000 (±50,000) pups, which would 

 lie i)rodueed by a herd of about l.o to 1.7 million. This is based on work dtme 

 by the Marine" Mammal Laboratory in Seattle and has been reviewed by other 



seal biologists. ..,.,, , , • .., • 



Question No. J. What is the present size of that herd, and how is this 



est i mated f 



Answer. We estimate that conservatively the total number of fur .seals in 

 the Pribilof Islands population slightly exceeds 1.2 million as follows: 



1969-70 



Average 

 1961-70 



p,,nc 305.000 



X|,2 ".::."""":". - 110,000 



Females > 3 years - - 560,000 



Malis>3 years 90' 0°° 



Total 1,215,000 



360, 000 

 180, 000 

 125, 000 

 650, 000 

 90, 000 



1, 405, 000 



This estimate is based on a combination of the estimates of the numbers of 

 pups born in 1069 and 1970. a weighted pregnancy rate, average survival rates, 

 and other estimates and counts including two tyi^es of marking programs. 



Question Xn. 6. If you know, please furnish information describing: 



( a ) The number of seals taken for each of the last ten years. 



(b) The age and sex of such animals. 



(c) When and under ivhat circumstances females have been taken. Were 

 these pregnant or nursing? 



(d) The size of the herd for these ten years. 



(e) Hoio many pups have been born for these years? 

 Answer. 6. (a) (b) (c). 



AGE AND SEX OF SEALS TAKEN, AND NUMBER OF PUPS BORN, PRIBILOF ISLANDS, 1961-70 



