FISHERY BULLETIN; VOL. 86, NO. 3 



APPENDIX 1 



The total prerecruitment (ZTotal,) and postjuvenile (ZAi) mortality 

 rates from 1979 through 1987 were estimated by 



ZTotal^ = -\og,iPart * 200,000) - \og,{Rt) 



and 



ZAt = log,(J,) - \og,iR,), 



respectively. The standard errors about ZTotal^ and ZAi were estimated 

 as the sum of the variances (Cochran 1965): 



■'ZTotal, - 





C.2 



SE^Tntal. = V + 



nt n^ 



and 



respectively. The variance estimates (5|^, Spavf) of adult recruitment 

 and spawning stock size were calculated from the log transformed 

 estimates from the daily lift rates at the Holyoke Dam, where Uf is the 

 total number of days in which 99% of the American shad were lifted. 

 The variance (Sj) about the juvenile abundance estimates (J^) was based 

 on the log transformed catches per seine haul from all stations and col- 

 lection dates, where rij is the total number of seine hauls made in that 

 year. 



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