APPENDIX A 



PREDICTION OF 1963 MALE RETURNS AND KILL 



Douglas G. Chapman 

 31 October 1962 



ESTIMATES OF ESCAPEMENT, 1962 



The usual method has been followed, i.e., 

 the estimation of the tail of the normal curve 

 from the kill, by round, of both 3- and 4-year- 

 old male seals on each island. The results 

 are shown in appendix table 1. 



The pattern of the kill by round was more 

 irregular than usual in 1962; this casts doubt 

 on use of the method to estimate the post- 

 season escapement. Evidence of unreliability 

 is seen in the large difference in percentage 

 escapements estimated for St. Paul Island and 

 for St. George Island. The estimate for St. 

 Paul Island appears particularly low. 



The escapement of undersized seals is es- 

 timated from the length distribution (appendix 

 table 25) among 3-year-old males sampled 

 from the kill on St. Paul Island. It appears 

 there is underrepresentation of animals < 41 



inches in length. Fitting a truncated normal 

 curve to the observations >42 inches yields 

 an estimate of escapement (due to size) of 

 5.0 percent. 



Considering the escapement of undersized 

 seals and making the usual adjustment of 

 17 percent in the escapement estimate for 

 downward bias, the estimated total escape- 

 ment of 3-year-old males on St, Paul Island 

 in 1962 is 8,726. Correspondingly, the returns 

 from the 1959 year class at age 3 are estimated 

 as 35,182. As noted, this estimate is probably 

 low. 



ESTIMATE OF RETURNS FROM DEAD-PUP 

 COUNTS 



The relationship between the return of 

 males at age 3 and dead-pup counts is again 

 recalculated, using the corrected 1958 figure. 

 The basic data are given in appendix table 2. 



APPENDIX TABLE 1. — ^Postseason escapement of male seals, Pribilof Islands, 



Alaska, 1962 



Island 



Age 

 class 



Male kill 

 2 July 

 to 

 2U August 



Estimated 



total 



in killable 



sizes 



Postseason escapement 



56 



