Impact of Oligotrophication, Temperature, and Water Levels on Walleye Habitat in the Bay of Quinte, Lake Ontario

Abstract

Recent environmental changes in the Bay of Quinte, Lake Ontario, have coincided with a decline in the stocks of walleye Sander vitreus. Suitable habitat supply was estimated in three sections of the bay during the summers of 1972–2001 to assess its role in the decline. An empirical model was developed to predict suitable habitat area for walleyes based on their preferences for cool water and low light intensity. The results indicated that lack of suitable light limits walleye habitat in the bay. Walleye habitat in the shallow upper bay has decreased at the rate of 34 ha/year since the invasion of dreissenid mussels in 1994, while that in the middle and lower bays has remained abundant. Walleye stocks and suitable habitat in the upper bay have both declined since the early 1990s. However, this pattern has not been consistent through time and suggests that other factors have also affected the Bay of Quinte walleye population. The analyses developed here can be used as a tool to enhance the assessment of walleye habitat dynamics in the Bay of Quinte and allow us to examine the impact of oligotrophication on the habitat of an important recreational and commercial species.