Genetic Analysis of Age and Size at Maturation in Salmon and Steelhead: Implications for Hatchery and Harvest Management

Age and size at maturation in anadromous salmonids are traits central to fitness in the wild and to performance in captivity. In addition to their direct contribution to population productivity, these traits influence plastic and evolutionary responses to human-caused selection by fisheries and environmental change. Salmonids show extensive diversity in age and size at maturation, and this diversity has important implications for management of hatchery production and harvest practices. Most studies have focused on characterizing the factors influencing inheritance of these traits in captive or hatchery-propagated populations. The availability of combined genotypic and phenotypic information from molecular pedigrees and increasingly powerful statistical tools to analyze them are providing unprecedented opportunities to study the evolution of these traits in wild salmonids. I summarize available information on genetic analyses of these traits in wild anadromous salmonids and use generalized animal models to quantify variation and potential for adaptive evolution from analyses of this information obtained from wild pedigrees and manipulated breeding designs.