Fish community structure in the Bay of Quinte, Lake Ontario: The influence of nutrient levels and invasive species

Abstract

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.

Nutrient management and structural shifts in fish assemblages: Lessons learned from an Area of Concern in Lake Ontario

“…Similarly, Hoyle et al. () reported an increase in the proportion of total fish community biomass represented by piscivores from 0.04 to 0.30 in the offshore and from 0.08 to 0.35 in the nearshore between the pre‐P and post‐P control periods, a decline to 0.15–0.21 post‐dreissenids, and an increase to 0.21–0.26 after round goby invasion. Thus, while the current values are greater than the threshold of 0.20, indicative of a balanced fish community (Brousseau & Randall, ; Hurley, ), it is important to note that the Bay of Quinte has a long history of abrupt shifts in its food web structure.…”

“…The objectives of our study also bear resemblance to those addressed by Hoyle et al. (); however, their study was based entirely on prespecified time‐stanzas (1969–1977, 1978–1994, 1995–2002, 2003–2009) which were compared with analysis of variance to identify statistically significant differences in the fish community over time. Our study extends the previous work in the following three directions: (1) we examine fish trends in time and space without any prior temporal binning (DLM), thereby allowing the identification of non‐monotonic patterns and potential stationary or inflection points in the time series; (2) we delineate the signature of important covariates (dynamic, piecewise, and multiple regression modelling), such as TP/chl‐ a , zooplankton, and surface water temperature on fish biomass; and (3) we develop risk assessment tools that can be directly used to guide fisheries and water quality management in the Bay of Quinte area.…”

“…poorly identified slopes) between fish abundance and year‐to‐year variability of surface water temperature. Nonetheless, historical evidence highlights that the observed change in fish populations following the sharp reduction in P inputs and reversal of eutrophication trends was partly confounded by the occurrence of weather extremes (Hoyle et al., ). Namely, white perch experienced catastrophic die‐offs in 1977–1978, probably associated with a severe winter, followed by an exceptionally strong year‐classes of yellow perch and walleye the next spring (Minns & Hurley, ).…”

“…However, Hoyle et al. (), using fish data from 1969 to 2009, provided evidence that fish community changes, after the invasion of round goby, were not as profound as the response to nutrient loading control or dreissenid invasion. The impacts of round goby may require more time to manifest themselves in the food web (Hoyle et al., ).…”

“…pumpkinseed ( Lepomis gibbosus ), bluegill ( Lepomis macrochirus ), black crappie ( Pomoxis nigromaculatus ), and largemouth bass ( Micropterus salmoides ), whereas walleye, white perch and alewife populations declined (Hoyle et al., ). In 1999, round goby ( Neogobius melanostomus ) invaded (Dietrich, Morrison, & Hoyle, ), reaching fairly high abundance levels after a short transitional period (Hoyle et al., ).…”