Intensive, long-term sampling in the Bay of Quinte with multiple gears (i.e. gill nets, bottom trawls, trap nets and boat electrofishing) allowed examination of the fish community and major fish populations in the context of key stressors up to 2009. Excessive nutrient input and hyper-abundant non-native fish species, White Perch and Alewife, shaped the depreciated fish community of the 1970s. After implementation of phosphorus input control measures and simultaneous winter-kills of the hyper-abundant non-native fish in the late 1970s, Walleye recovered and served to restore a predator-prey balance to the fish community by the late 1980s. However, in the absence of a significant recovery of submerged aquatic vegetation (SAV) in littoral areas, off-shore species (e.g. Alewife and White Perch) still tended to dominate; even in littoral areas. Following establishment of Dreissenid Mussels in the mid-1990s, water transparency increased and SAV increased significantly in littoral areas. This pivotal event led to a shift in the fish community that included an overall decline in Walleye, an increase followed by a decrease in Yellow Perch, and dominance by centrarchids (i.e. Bluegill, Pumpkinseed, Black Crappie and Largemouth Bass) in the nearshore. Round Goby invaded in 1999, proliferated and became important in the diet of piscivores by 2003. The current species assemblage, including the piscivores, is diverse and indicative of a healthy fish community.

Bay of Quinte IBI scores increased significantly between 1990 and 1999 due to changes in relative species richness and (3) differences in fish communities were correlated with physical habitat attributes at survey locations. Data from both nearshore electrofishing and trap net surveys confirmed that the Bay of Quinte supports a highly productive and diverse fish community.

Biomass and growth of Pumpkinseed ( Lepomis gibbosus), Yellow Perch ( Perca flavescens) and cohabiting species varied among different bays of Prince Edward County in eastern Lake Ontario. Biomass (B) and a calculated fish production (P) index of fishes, estimated as the product of average seasonal biomass and P/B, was about 6x higher at the electrofishing transects with medium to high macrophyte cover and low fetch than at sites where macrophytes were absent or sparse and fetch was high. The production index -aquatic plant relationship was species-dependent. The biomass component of fish production was related to macrophyte cover but the growth component and P/B (determined by allometry with body size) was not. Biomass and inferred production could be predicted from fetch, macrophyte abundance and water temperature, but with low precision. Results were consistent with index trawling in showing that changes in aquatic vegetation following Dreissena colonization in the Bay of Quinte and vicinity have affected the abundance of phytophilic fishes in this region of eastern Lake Ontario.

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