Piscivority in a Land-Locked Alewife (Alosa pseudoharengus) Population

Abstract

Larval fish were a frequent dietary component of alewives (Alosa pseudoharengus) from Claytor Lake, Virginia, USA. Alewives consumed the young of four game and two forage species (maximum 26 mm total length (TL)). Alewife piscivority appeared to be at least partially nocturnal and was more prominent in littoral than in limnetic areas. Predator and prey lengths were positively correlated, although morphological limits on larval fish ingestion by alewives were not severe. Peak occurrence (40–70%, June 1978) of larval fish in alewife stomachs coincided with a precipitous decline in zooplankton density. Zooplankton abundance was higher in early summer 1979, when alewife piscivority was less common. Our findings support the hypothesis that alewife piscivority could have contributed to the collapse of Great Lakes resident fish populations following alewife establishment. Alewife piscivority should be considered in risk–benefit evaluations prior to introducing alewife as a pelagic forage species.Key words: alewife, Alosa pseudoharengus; feeding ecology, larval fish, Great Lakes fisheries, forage introductions