Table 28. --Forecasted and actual kill of male seals, 

 Pribilof Islands, Alaska, 1966 



Total 



St. George 



Total 



43, 000 



42, 079 



2 + 5 

 3 

 4 



1, 000 

 7, 000 

 3, 000 



893 

 5, 586 

 3, 881 



11, 000 



10, 360 



Total both islands 



54, 000 



52, 439 



Table 29. --Estimated numbers of yearling male seals, 

 year classes 1961, 1962, and 1964, Pribilof Islands, 

 Alaska 



Yearling Estimate 



Except in 1964, we have selected and tagged 

 yearling seals on St, Paul Island each year 

 since 1961 (see section on marking) toprovide 

 a basis for estimating the size of the year 

 class in the autumn of birth and again at age 1. 

 The estimated numbers of yearling males for 

 year classes 1961, 1962, and 1964 are listed 

 in table 29. Though information from this 

 source on the size of the pup population in 

 autumn is not now used to predict the size 

 of the kill at age 3, we discuss it here because 

 of its potential use for this purpose. 



Estimates of the number of yearlings are 

 based on tag recoveries from both islands. 

 The 1961 and 1963 year classes, apparently 

 almost identical in size at age 1, produced 

 through age 4 harvest of 45,484 and 41,501 

 animals, respectively. Because the relative 

 standard deviation of the difference between 

 these two estimates was about 8 percent, 

 the difference between the kills from the two 

 year classes to date can be reasonably at- 

 tributed to sampling errors. The difference 

 may also reflect variability in survival after 

 age 1, however, as well as differences in 

 ultimate escapement. 



The meaning of the difference between 

 harvests from the 1961 and 1962 year classes 

 is much less important than the interpreta- 

 tion of the currently available estimate of 

 the number of yearlings alive in 1965 (from 

 the 1964 year class). A simple comparison 

 of this estimate with completed estimates of 

 the number of yearlings alive in 1962 and 

 1963 (year classes 1961 and 1962) suggests 

 that the kill on St. Paul Island at ages 3 

 and 4 from the 1964 year class should be 



7n ft 



-^f^ X 33.000 or 30,000. Here, 33,000 is the 



( o 



average of the kill on St. Paul Island at ages 

 3 and 4 from the 1961 and 1962 year classes. 

 If, however, we assume a constant bias in the 

 estimates of yearlings based on tag recoveries 

 at age 2, then the yield from the 1964 year 

 class could be estimated as: 



(Yield of the 1962 year class at ages 3 and 4 

 times the estimate of the number of yearlings 

 from the 1964 year class from tag recoveries 

 at age 2) -=- (Estimate of the number of yearl- 

 ings from the 1962 year class from tag re- 

 coveries at age 2) 



(31,158) 



70.8 

 34.5 



63,941 or 64,000 



Estimates of the number of yearlings based 

 on recoveries at age 2 may be biased if some 

 of the yearlings did not return to the islands 

 at age 1 and if some of the same group hauled 

 out on the islands as 2-year-olds after the 

 killing season. Whether the proportion of the 

 group that remains at sea or arrives late is 

 constant from year to year is a matter of 

 conjecture at this time. 



Because of the great discrepancy between 

 the two estinnates --one extremely high and 

 the other low--we prefer not to use this ap- 

 proach to predict the size of the kill at age 3 

 until some of the questions can be answered. 



30 



