The foraging and schooling ecology of lake herring ( Coregonus artedi) in Lake Opeongo

The lake herring (Coregonus artedii) are the primary prey of lake trout (Salvelinus namayeush) in Lake Opeongo. Lake herring aggregate into schools under suitable light conditions but disperse under low light. Suspended gillnets were used to capture lake herring aggregations during the daytime and dispersed individuals during the night. The literature on schooling suggests that the behaviour is sustained as a function of predator avoidance. Results show that lake herring continue to school at light levels well below those predicted by a reactive distance model for lake trout. This suggests that schooling may provide other advantages. This work indicates that lake herring are able to forage more effectively during the daytime while schooling than when dispersed at night. Not only are individual lake herring able to consume more prey while in a school, but results suggest that schooling may actually enhance foraging opportunities for individual members through mechanisms such as the “Many Eyes” hypothesis.