Hatchery Origins of Naturally Produced Lake Trout Fry Captured in Lake Ontario: Temporal and Spatial Variability Based on Allozyme and Mitochondrial DNA Data

January 1, 1994 - Author: P. M. Grewe; C. C. Krueger; J. E. Marsden; C. F. Aquadro; B. May

Journal or Book Title: Transactions of the American Fisheries Society

Volume/Issue: 123

Page Number(s): 309-320

Year Published: 1994

Stocking of juvenile lake trout reared in hatcheries has been one of several management actions used to restore self-sustaining populations of lake trout Salvelinus namaycush in the Great Lakes. Since 1973, Lake Ontario has been stocked predominately with Oearwater, Jenny, Killala. Manitou, Seneca. and Superior strains. Reproductive success of these strains was assessed by using allozyme and mitochondrial DNA (mtDNA) characters with mixed-stock analysis. Parental origins of wild fry were compared over several years at Stony Island reef and between Stony Island reef and Yorkshire Island reef in 1990. Strain origins at Stony Island reef were examined among four year-classes (1986, 1988. 1989. and 1990) of wild fry and among three year-classes (1988, 1989. 1990) of fry reared from eggs collected in late autumn. Allelic frequencies were not different among year-classes within the wild fry and egg collections from Stony Island reef (P ~ 0.05). Frequencies of mtDNA haplotypes also were not different among the 1988. 1989. and 1990fry samples (mtDNA data were unavailable for the 1986 sample). Allozyme comparisons between fry and egg samples over the three year-classes indicated that embryos collected in autumn were genetically similar to fry the next spring. Based on mixed-stock analysis, 67-90% of parental contributions were from the Seneca strain; the remaining contribution was attributed to Killala and Superior strains. At the Yorkshire Island site, only eggs were sampled and analyzed (no fry). In contrast to Stony Island, strain contributions to this sample were 35% Killala, 28% Manitou, and 23% Superior. Hatchery strains identified at the Yorkshire Island site fertilized and deposited eggs but do not appear to produce fry (only two fry were collected over a 3-year period). Thus, the suitability of strains other than Seneca in producing wild fry remains in question. The consistent reproductive success of the Seneca strain over 5 years at Stony Island reef relative to their low level of stocking indicates the suitability of this strain for restoration of lake trout popUlations at shallow-water reef locations in Lake Ontario.

Type of Publication: Journal Article


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