Abstract:
Climate change can have both direct and indirect impacts on food webs and fish
populations. Growing evidence suggests that these impacts are affecting the relative abundance
and presence of freshwater fishes. It may be possible to detect climate-induced changes in game
fish populations by analyzing data from Fishbrain, a smartphone application that anglers in the
United States have used to report catches from 2015-2020. We used generalized linear mixedeffects
modeling to determine the temporal trend in catch proportions by subbasin, and then
mapped the location of these trends to identify spatial patterns. Results suggest that warm-water
species are becoming more common in catches, usually at the expense of cool-water species.
These patterns were strongest in the Great Lakes region, the Northeast, and parts of the West
Coast. Single-species analyses detected increases in Largemouth Bass (Micropterus salmoides),
declines in Channel Catfish (Ictalurus punctatus), Northern Pike (Esox lucius), and Rainbow
Trout (Oncorhynchus mykiss), patchy results for smallmouth bass (Micropterus dolomieu), and
no response in bluegill (Lepomis macrochirus). Spatial results of the single-species analyses
were interesting and will be discussed. Despite the short time frame of this study (6 years), our
analyses of catch data produced results that were consistent with expected changes in the relative
abundance of game fishes in response to climate change. Future work should focus on refining
the use of app data as a tool for monitoring game fish responses to climate change, especially as
the length of the time series increases.
