Feeding ecology of longfin smelt (Spirinchus thaleichthys Ayres) in Lake Washington

Abstract Stomach contents of longfin smelt collected in Lake Washington, 1985–1991, were analyzed to assess feeding habits. Copepod species dominated prey biomass consumed by young of the year smelt in summer whereas Daphnia , chironomid larvae, and copepod species were the most important prey in fall. Diet of 1+ smelt, expressed in terms of percent dry weight, consisted mainly of mysids, amphipods, and Daphnia . The mean number of mysids observed in smelt stomachs in this study was about 50% lower than in the 1960s. This change in smelt diet is related to changes that have occurred in the Lake Washington watershed, and in the zooplankton composition in the lake following recovery from eutrophication; a reduction in growth of smelt accompanied this.