Comparative Ecology and Behavior of Domestic, Hybrid, and Wild Strains of Brook Trout, Salvelinus fontinalis, after Stocking

Abstract

Two years after planting in six small oligotrophic lakes, domestic, hybrid and wild strains of brook trout, Salvelinus fontinalis, used space and food resources in the same way as native trout. Although trout living with or without white sucker, Catostomus commersoni, were similarly spatially distributed, they had different diets, suggesting a feeding niche shift of trout in the presence of sucker; we concluded that this shift is under phenotypic control because each planted strain came from similar genetic backgrounds. Sexual maturity was related to the size of individuals, regardless of the strain, and males matured before females. Almost all males and females were sexually mature in the first fall after stocking except wild females (3.0 and 75% matured during the first and second fall, respectively). Gonadosomatic indices (GSI) of domestic and hybrid females were similar during the first fall, but the GSI of domestic females was significantly higher than that of hybrid and wild strains in the second fail. Mean egg diameters were similar among the three strains during the two falls, but fecundity of domestic females, after correction for size differences, was significantly higher than that of hybrid females which, in turn, was significantly higher than that of wild ones.