This data release includes Lake Ontario prey fish data including species captured, relative abundance, spatial distribution, size structure, and age data from the April or spring prey fish bottom trawl survey, 1978 through 2022. Data from 1978 - 2015 are from U.S. waters of Lake Ontario while data from 2016 - 2022 include both U.S. and Canadian waters of Lake Ontario. Details about the vessel and gear descriptions, sampling protocols, and catch processing protocols are provided in the associated metadata. Portions of this data release follows the data model of the USGS Great Lakes Science Center Research Vessel Catalog (RVCAT). The trawl data included in this data release are a subset of the larger RVCAT data base. The RVCAT data can be found here: https://doi.org/10.5066/F75M63X0.