Spatial Community Ecology, Cannibalism, and the Resilience of Lake Champlain Forage Fish

Rainbow smelt (Osmerus mordax) and alewife (Alosa pseudoharengus) are pelagic fish species native to coastal regions of northeastern North America. Rainbow smelt are native to Lake Champlain, and alewife were first found in the lake in 2003. During the expansion of Lake Champlain’s alewife population, survival of age-0 rainbow smelt and alewife was studied in relation to adult abundance and habitat gradients in the aquatic environment. Spatial dynamics of these species are particularly important because both are cannibalistic, with cannibalism rate a function of spatial overlap and fish density. Using data collected over both diel and seasonal cycles, we determined what temperature and light conditions influenced adult and young fish spatial distributions and created models predicting rainbow smelt and alewife distribution. Distribution predictions were then coupled with previously-created predation models to simulate predation and cannibalism patterns under current and possible future lake scenarios. Our data show, and models predict, that alewife and rainbow smelt populations interact differently under divergent future climate, and subsequent limnological, scenarios. Our work also predicts, due to the importance of cannibalism, that neither species will extirpate the other.