Genetic Gain for Growth and Delayed Sexual Maturation Using a Feral Strain of Anadromous Brook Trout

Abstract

A selective breeding program was initiated with a wild population of anadromous brook trout Salvelinus fontinalis from the Laval River, Quebec. The objective was to develop a new strain characterized by improved growth and reduced precocious sexual maturation. A control line was maintained by use of random within‐family selection. Length and weight were measured and sexual maturity (mature or not mature) was determined at the end of the second year of growth (22 months of age). In the selected line, phenotypic variance, additive genetic variance, and heritability for weight within the selected families were reduced. A comparison between generations showed that fish weight at 22 months in the selected line increased by 23.1% from the F1 to the F2 generation and by 32.1% from the F2 to the F3 generation. The control line increased similarly in weight from the F1 to the F2 generation (34.7%) but not thereafter; this result was probably due to the domestication effect in the first generation after captivity. The proportion of fish that were immature at 22 months was 32.2% in the F1 generation and increased to 61.4% by the F3 generation in the selected line; the proportion immature did not change significantly after two generations in the control line (27.5%). Our results show that simultaneous selection for growth and late sexual maturation are compatible goals for brook trout breeding programs.Received April 29, 2009; accepted August 9, 2010

Growth regulation in brook charr Salvelinus fontinalis

“…A selective breeding program described by Bastien et al (2011) and Sauvage et al (2010) was initiated in 1994 using wild S. fontinalis from the Laval River (Québec; 48.449° N, 68.059° W). Briefly, a combined between-and within-family selection protocol was applied based on 1) the absence of precocious sexual maturation at 22 months and 2) growth performance in sexually immature fish.…”

“…Briefly, a combined between-and within-family selection protocol was applied based on 1) the absence of precocious sexual maturation at 22 months and 2) growth performance in sexually immature fish. A control line was created by the arbitrary selection of equal numbers of fish from each family for every generation (i.e., domestication to culture conditions, but no intentional selection) (Bastien et al 2011). This line was maintained over the same period, which allowed us to perform studies aimed at tracking temporal genetic and phenotypic changes occurring in selected vs. control strains lines reared in the exact same environment.…”

“…Large males, which may be preferred by females, can dominate competitors in contests for mates or breeding territories, and large females can produce more and larger offspring than small ones (Perry et al, 2005;Anderson et al, 2010). Aquaculture production aims to produce large fish that would invest in growth instead of reproduction and that would best adapt to the captive environment (Gjedrem, 2005;Sauvage et al, 2010;Bastien et al, 2011). Selective breeding exploits the substantial genetic variation that is present for desirable traits.…”

“…Selective breeding exploits the substantial genetic variation that is present for desirable traits. Thus, a high growth rate as well as the absence of early sexual maturity are the most used criteria since energy is preferentially invested in growth rather than in gamete production (e.g., Nilsson, 1990;Bastien et al, 2011).…”

“…Significant heritability for traits related to the accumulation and use of energy reserves was found in two out of three different strains used by the Québec fish-farming industry, which include the Laval strain (Crespel et al, 2013). Domestication has led to large increases in fish weight: for S. fontinalis from the same Laval strain, the weight of selected fish at age 22 months increased by 23% between the F1 and F2 generations and by 32% from F2 to F3 (Bastien et al, 2011).…”