APPLYING SURVIVAL CURVES 43 



where N^ is potential adult loss, Nl is number of larvae entrained, 

 and Sla is survival from hatching to adult. It was proposed that Sla 

 be estimated indirectly from 



Ska 

 Sla = Sit W 



where Sea (survival from egg to adult) is 2/F and Sel is an 

 estimated or observed survival rate from egg to hatching of larvae. 

 Lifetime fecundity, F, is 



F = G L P.Ei (5) 



i=l 



where Pj is fraction of population in each age class, E, is egg 

 production or fecundity for each age class, and G is mean generation 

 time in years. Since appropriate data for Oneida Lake walleyes are 

 lacking, F is calculated for Lake Erie walleyes (Table 2). Mean 

 generation time is estimated as 3 years in this case to correspond to 

 the age of maximum eggs per female. An intermediate adult age, such 

 as 5 years, can also be selected to provide possible minimum and 

 maximum generation times (Horst, 1977b). This procedure yields 

 Sea values of 4.3728 x IQ-^ and 2.6240 x 10^^ The utility of 

 this approach is supported by an independent calculation of 

 egg-to-adult survival (3.5846 x 10~^), which represents the ratio of 

 adults and egg production in the unstocked population, as shown in 

 Table 1. 



If we limit further calculations to the unstocked population, 



_ Sea _ 4.372 x IQ-' _ 0.00004372 _ ^ ^, ^^„ 

 ^LA = S^ ^ 4.213 X 10-^ ^ 0.004213 = ^'^^^^^ 



where Sel is ratio of larva at hatching and egg production (Table 1). 

 This value of Sla is approximated by the ratio of adults to larvae at 

 hatching (0.0085) in Table 1. The product of Sla and the number 

 of larvae entrained (Nl = 2.26 x 10*"), as in Eqs. 1 and 3, yields a 

 potential adult loss of 23,436. 



The use of hatching-to-adult survival for Sla is questionable 

 since survival to adulthood increases from 1 to 15.5% through the 

 pelagic larva period (survival rate is the ratio of adults to larvae). To 

 make the calculation of larval entrainment losses correspond with the 



