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.

湖鳟 ( Salvelinus namaycush ) 是一种具有重要生态和经济意义的食鱼动物，据报道在其整个范围内的饮食和摄食行为存在差异。使用 11 个胃含量和基于稳定同位素的指标来描述安大略湖两年（2013 年至 2018 年）和地理区域（西部、中部、东部、金斯敦盆地）之间 349 条湖鳟的饮食。使用个体（例如，体积，%V）和总体（例如，相对重要性指数，%IRI）饮食指标，我们发现2013 年在一些地区的湖鳟饮食中，鲑鱼（ Alosa pseudoharengus ）占绝对优势（%V = 23.3 – 92.7；%IRI = 12.2 – 99.5）和 2018 年的所有区域（%V = 83.9 – 96.7；%IRI = 96.5 – 100）。圆形虾虎鱼 ( Neogobius melanostomus ) 和彩虹鱼 (Osmerus mordax）是次要的湖鳟猎物，其相对饮食百分比仅通过猎物丰度的空间和时间变化略微反映（圆虾虎鱼：%V = 1.0 – 33.3，%IRI = 0.1 – 13.2；彩虹鱼：%V = 2.5 – 54.0，%IRI = 0.1 – 54.0)。碳 (δ ¹³ C) 和氮 (δ ¹⁵ N) 同位素生态位区域和方向在所有年份区域组合中相似，增强了湖鳟饮食的时空一致性。这项研究的结果推进了描述安大略湖湖鳟饮食的时间序列，并可用于补充与不同鲑鱼群落承载能力相关的种群评估和管理决策。