Identification of Parental Origins of Naturally Produced Lake Trout in Lake Ontario: Application of Mixed-Stock Analysis to a Second Generation

Abstract
Management decisions related to the restoration of a self-perpetuating population of lake trout Salvelinus namaycush in Lake Ontario would be improved with information about differences in the reproductive success of stocked strains. Assessment of differential reproductive success of naturally spawning mixed-stock fish populations requires the use of genetic markers that are transmitted between generations. This paper describes the identification of hatchery lake trout strains that successfully reproduced on a single reef in Lake Ontario in 1986. The analysis used allozyme data from parental stocks and naturally produced young and represents a novel application of the maximum-likelihood method of mixed-stock analysis. Lake trout sac-fry captured in 1986 in Lake Ontario were estimated to have been produced by Seneca × Seneca strain (78%) and Seneca × Superior crosses (20%), although the Seneca × Superior estimate was not significantly different from zero. Eight other strains and strain hybrids wer...