Researchers from Minnesota, Wisconsin and Missouri talk about their work in quantifying the impacts of climate change on fish growth and production using the largest-ever database of Midwest glacial lakes fisheries surveys to enable sustainable management.

Climate change is causing inland lake water temperatures to rise, ice durations to shorten, and stratification regimes to shift. These habitat changes are creating novel challenges for freshwater fish and the productive fisheries they have long supported. We assessed shifts in habitat availability, bioenergetic needs and capacity, fish growth, and fishery productivity using simulated water temperature data and fisheries monitoring data compiled from across the Midwest.

Major findings include:

1. On average, species preferring colder temperatures lost more preferred habitat than was gained by species favoring warmer temperatures between 1980-2021.
2. While warm-water species’ productivity has generally benefited from warming, cooler-water species have generally lost productivity. These losses in productivity can be exacerbated by fishing in exploited populations.
3. Many cool- and coldwater fish will experience increasing energetic challenges as the climate warms, but thermal refuges will likely persist in larger and deeper lakes.
4. The growth patterns of fish can be influenced by temperature–and theory allows us to predict what these patterns look like, but do fish actually follow these predictions? We explore this as a product of methodological and ecological mechanisms.
5. The effects of temperature on fish growth differ depending on fish size and age. Rising temperatures may accelerate early life growth for some species, but slow growth and increase mortality for older life stages.

Collectively, this can result in complicated responses of fish growth across the diverse landscape of Midwestern lakes. Together, these projects provide an actionable set of findings for managing fisheries under climate change.