For generations, freshwater fishing has provided food, recreation, and a way for families and communities to connect with nature and each other. But as lakes warm and ice cover declines, species that thrive in warmer water are appearing more often in lakes historically popular for coolwater and coldwater fishing, raising questions about the future of those valued fisheries. 

USGS scientists with the National CASC, Midwest CASC, and Missouri Cooperative Fish and Wildlife Research Unit, together with partners, analyzed recreational fishing data from 587 lakes across Michigan, Minnesota, and Wisconsin to understand how warming lake temperatures are changing fisheries in the region. Coolwater fish prefer temperatures between 19-25°C, and coldwater fish prefer even colder conditions. When temperatures exceed these ranges, the fish can experience stress that affects their survival, growth, and reproduction.  

The scientists found that warmwater fish already make up a larger share of anglers’ catch than in the past, especially in lakes with higher surface temperatures and less ice cover. Using climate projections for mid-century (2040-2060), they also found that warmwater fishing opportunities are likely to continue expanding.  

But not all lakes are expected to change in the same way. Lakes larger than 100 hectares and deeper than 10 meters, in addition to those expected to remain relatively cool, may continue to offer thermal refuges for prized coolwater and coldwater fish.  

For fisheries managers, this uneven change creates both challenges and opportunities. In lakes that retain cooler habitat, managers may be able to sustain historical fisheries. In smaller more rapidly warming lakes, however, they may need to prepare for the increase in warmwater species and new angling opportunities. 

These changes extend beyond the fish themselves. Shorter and less stable winter ice conditions are already making ice fishing more difficult and dangerous in some places. As anglers catch different fish from familiar waters, sustaining popular fisheries, and the traditions tied to them, will depend on adaptation strategies tailored to individual lakes and how they are changing.  

To uncover these patterns, the scientists paired fishing catch records from CreelCat – the U.S. Inland Creel and Angler Survey Catalog, a database and interactive tool developed by the National CASC for fisheries management and research, with lake surface temperature, ice cover, and lake morphometry data, including lake size and depth. 

The article titled “Lake temperature and morphometry shape the thermal composition of recreational fishing catch” was published in the journal Transactions of the American Fisheries Society. 

This research was supported by the National CASC project titled “Integrating Multiple Data Sets to Inform Climate Adaptation Strategies for Inland Fish and Recreational Fishing.”