Spatial and temporal variability in lake trout diets in Lake Ontario as revealed by stomach contents and stable isotopes

Journal of Great Lakes Research
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Abstract

Lake trout (Salvelinus namaycush) are an ecologically and economically important piscivore with reported differences in diet and feeding behaviour throughout its range. Eleven stomach content and stable isotope-based metrics were used to describe diets of 349 lake trout between two years (2013 and 2018) and among geographic zones (west, central, east, Kingston basin) in Lake Ontario. Using individual (e.g., volumetric, %V) and aggregate (e.g., index of relative importance, %IRI) diet metrics, we found an overwhelming dominance of alewife (Alosa pseudoharengus) in lake trout diets among some zones in 2013 (%V = 23.3 – 92.7; %IRI = 12.2 – 99.5) and all zones in 2018 (%V = 83.9 – 96.7; %IRI = 96.5 – 100). Round goby (Neogobius melanostomus) and rainbow smelt (Osmerus mordax) were secondary lake trout prey items with relative diet percentages only marginally reflected by spatial and temporal variation in prey abundance (round goby: %V = 1.0 – 33.3, %IRI = 0.1 – 13.2; rainbow smelt: %V = 2.5 – 54.0, %IRI = 0.1 – 54.0). Carbon (δ13C) and nitrogen (δ15N) isotopic niche areas and orientations were similar across all year-zone combinations reinforcing temporal and spatial consistency in lake trout diet. The findings of this study advance the time series in describing Lake Ontario lake trout diets and can be used to complement stock assessments and management decisions associated with carrying capacity for the diverse salmonid community.

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Publication type Article
Publication Subtype Journal Article
Title Spatial and temporal variability in lake trout diets in Lake Ontario as revealed by stomach contents and stable isotopes
Series title Journal of Great Lakes Research
DOI 10.1016/j.jglr.2020.08.004
Edition Online First
Year Published 2020
Language English
Publisher Elsevier
Contributing office(s) Great Lakes Science Center
Country Canada, United States
Other Geospatial Lake Ontario
Google Analytic Metrics Metrics page
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