Depreciation of the Warmwater Fish Community in the Bay of Quinte, Lake Ontario
The sequence of fish species shifts since the 1930s in the Bay of Quinte is interpreted in terms of climatic changes and the influences of man. Among the latter, eutrophication is judged most important. The marked decrease in large piscivores in both eastern Lake Ontario and the Bay of Quinte as a consequence of these changes resulted in instability, exemplified by the explosions in populations of alewife (Alosa pseudoharengus) and white perch (Morone americana). Nutrients are imported to the bay, from Lake Ontario by way of alewife. This source has increased in the 1970s with the further decline of piscivores, and it brought about a greater fish production in the bay. We conclude that the Bay of Quinte and Lake Ontario interact significantly and should be studied as a single system.Because of its specialized feeding habits, the post-World War II rise of the walleye (Stizostedion vitreum vitreum) was related to events outside the Bay of Quinte, but its later decline was attributable to direct and indirect effects of eutrophication. Yellow perch (Perca flavescens), by contrast, were apparently not affected adversely by severe habitat changes induced by cultural eutrophication. Key words: Percidae, community ecology, species shifts, eutrophication, habitat changes