Responses of Sockeye Salmon (<i>Oncorhynchus nerka</i>) to Fertilization of British Columbia Coastal Lakes

Abstract

Addition of nitrogen and phosphorus fertilizer to several British Columbia coastal lakes has resulted in increased autotrophic and heterotrophic production and larger standing stocks of zooplankton. These changes at the primary and secondary trophic levels are reflected by increased in-lake growth of juvenile sockeye salmon (Oncorhynchus nerka) and larger outmigrant smolts. Evidence is presented that smolt size changes in fertilized lakes will lead to increases in the harvestable surplus of sockeye adults by promoting both increases in marine survival and an earlier age-at-return to the fishery.