Comparative population dynamics of bloater in Lake Michigan and Lake Huron

Understanding the mechanisms that drive population dynamics has long been a fundamental goal of fisheries ecology.  One common approach to identify general recruitment mechanisms is to examine multiple populations of a species in a single analysis.  Here, we used data from long-term bottom trawl surveys to determine how intrinsic factors influence recruitment of bloater, an important native planktivore in the upper Great Lakes.  Using dynamic linear models, we determined how total egg production, sex ratio, and the condition of adults in the spawning population influence recruitment dynamics in lakes Michigan and Huron.  Bayes Information Criterion revealed that models that included all three variables best explained variation in bloater recruitment in both lakes, suggesting that similar mechanisms are operating in both lakes.  However, an examination of the standardized regression coefficients revealed that the direction and the relative magnitude of the effects attributed to these intrinsic factors differed considerably between lakes.  In the future, we plan to expand these models to include extrinsic climatic variables (temperature, ice cover, water level) as well as additional species (alewife, rainbow smelt).