Lake Ontario Spring (April) Prey Fish Bottom Trawl Survey, 1978-2025

This data release includes Lake Ontario fish data from the April or spring prey fish bottom trawl survey, conducted by multiple agencies from 1978 through 2025.This survey goal is to quantify the relative abundance and population dynamics of prey or forage fishes, and in particular Alewife (Alosa pseudoharengus), which inform fisheries managers that decide on Lake Ontario predator fish stocking levels. This survey and associated data are also used to quantify the status of native fishes of conservation concern. Data tables describe the vessel and trawl operations, number and weight of species caught, relative abundance, size structure, and age interpretations. Data from 1978 - 2015 are from surveys covering only U.S. waters of Lake Ontario while survey data from 2016 - 2025 include both U.S. and Canadian waters of Lake Ontario. The data set also includes hydroacoustic prey fish density estimates for portions of the water not sampled by the bottom trawl (2021-2025). Details about the vessel and gear descriptions, sampling protocols, and catch processing protocols are provided in the metadata.