Status of Yellow Perch Stock and Fishery Management in Lake Saint-Pierre, Québec

Lake Saint-Pierre, an enlargement of the St. Lawrence River, supported important yellow perch commercial and sport fisheries until the mid-1990s. High exploitation rates combined with poor recruitment during the 1988–1998 period led to a 70% decline in fish abundance and a three-fold decline in declared commercial catches. Despite a major reduction in commercial and sport fishing since 1997, low recruitment has persisted: the yellow perch stock gradually declined and finally collapsed. Habitat quality decline and benthic cyanobacteria proliferation in nursery areas have contributed to the reduction in food quantity and availability, with an impairment of juvenile yellow perch growth and recruitment. Habitat changes also led to an unexpected and long-term shift in the fish community structure towards omnivorous benthic fish; this change is indicative of anthropogenic stress conditions. Among the other possible causes for poor recruitment are the destruction of spawning areas in the floodplain, climate changes, low abundance of mature females, and predation by cormorants. Given that Lake Saint-Pierre represents a complex fluvial system that is rapidly evolving under strong natural and anthropogenic pressures, the next management plan designed to rehabilitate the ecosystem must include major measures to improve habitat quality as well as yellow perch stock restoration.