Age at sexual maturity and its association with growth rate and body size has receive d considerable attention by geneticists working with salmonid fish. The three traits are highly interrelated and rap idl y growing fish mature at earlier ages and at a larger sizes than slow growing fish, within stocks and year- classes. There may be a minimum threshold body size required for expression of sexual maturity. The effects of body size and growth on maturity are confounded with factors affecting season of spawning; fish not achieving the threshold size in one season continue to grow until the next season, at which time they appear larger and older. The heritability of age at sexual maturity appears to be between 0.2 and 0.4, similar to that for body size. Age at sexual maturity is nega ti vel y correlated with body size and body size is pos i t i v e l y correlated with the proportion of early maturing fish in sib-groups. The use of precocious males results in an increased proportion of precocious males in the progeny generation.
Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume X. Breeding programs for swine, poultry, and fish., , 401–410, 1986
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