Fisheries-Induced Selection Pressures in the Context of Sustainable Fisheries

Man has a major impact on marine environments through exploitation of fish resources. Fisheries can induce different selective pressures, either directly, i.e., through elevated mortality (which is often highly selective) or through ecosystem-level responses, as exploitation affects food availability and predation risk in both target and nontarget species. Responses to selection can be observed at two levels. First, at the community level, some species may suffer more from effects of harvesting than others; some may even increase in abundance. Responses by species to exploitation are associated with their life histories. In particular, species with late maturation at large size and with low population growth rate tend to undergo more pronounced declines than early-maturing species with rapid growth. Second, the phenotypic composition within species may also change. If phenotypic variability has a genetic basis, then fisheries-induced selection can result in evolutionary change in life-history traits influencing sustainable yields, behavioral traits (e.g. gear-avoidance behavior), and morphological traits. We discuss the possible implications of fisheries-induced adaptive changes for sustainable fisheries management