APPENDIX A 



PREDICTION OF 1964 MALE RETURNS AND KILL 



Douglas G. Chapman 

 2 January 1964 



Four-year-old Males 



Method l.--The postseason escapement of 

 3-year-old males in 1963 was calculated by 

 fitting a normal curve to the kill, by round, 

 of this age class. This method indicates that 

 74.2 percent of the 3-year-old males of the 

 proper body length were taken by 5 August 

 1963. Because the round system was not used 

 on St. George Island, the estimate of 74.2 

 percent was based on data collected on St. 

 Paul Island. 



The method of estimating then proceeds as 

 follows: 



Total return of 3-year-old males of the 



proper body length 



13,954 

 .742 



18,806 (13,954 



3-year-old males taken on St. Paul Island by 

 5 August 1963) 



Total kill of 3-year-old males on St. Paul 

 Island in 1963 (to 26 August) = 14,310 



Escapement (postseason is 18,806 - 

 14,310 = 4,496) 



4 496 

 Percentage escapement is 100 x . ' ., 



24 



Using 5 as an average percentage escape- 

 ment due to body length, the total escapement 

 percentage is 1 - (.95)(.76) = .28 x 100. 



The total escapement is 



14,310 

 .72 



14,310 



5,565, which is then adjusted by the 17 per- 

 cent correction worked out emperically after 

 the extended 1956 and 1957 seasons. Hence, the 

 escapement is (5,565) (1.17) = 6,511. 



The kill of 4-year-old males is forecasted 

 as 85 percent of this escapement, or 5,500. 



Method 2. -- Data on the kill of 3- and 4-year- 

 old male seals and the mean date of the kill 

 of 3-year-olds are given in appendix table 1 

 for year classes 1952-59. 



Because killing was terminated on various 

 dates over the years, the data were stand- 

 ardized by considering the kill to 31 July only. 

 In years in which killing continued after 31 

 July, 80 percent of the 3-year-old males taken 



Appendix table 1. — Forecast of the 4-year-old male kill from 

 the mean date and kill of 3-year-old males, St. Paul 

 Island, year classes 1952-59 



1 Kill of 4-year-old males to 31 July, plus 80 percent of 

 the number of 3-year-old males taken after 31 July. 



2 Adjusted to the base of a common starting round on 

 27 June. 



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