Abstract
Fish populations and water quality in the Great Lakes are highly susceptible to changes at either the bottom or top end of the food chain. Factors which affect fisheries and water quality include toxic contaminants, weather conditions, climate changes, species invasions, and evolutionary changes in native species. Management of water quality could directly affect the $2-4 billion annual fisheries revenues. When causal relationships in the food web are diagrammed, inadequate data are highlighted, as are possible approaches to improved fisheries management.