LANSING — New research shows that some Michigan fish species are becoming smaller in response to a changing climate.
The University of Michigan study on fish length analyzed 75 years of data from nearly 1,500 inland lakes.
Researchers found a small drop in the length of various fish across age and species from 1945 to 2020, a development that they say could raise concerns about the longevity of some populations.
“Those changes in fish size were strongly related to changes in lake temperatures,” said Kevin Wehrly, manager of the DNR’s Institute for Fisheries Research and co-author of the study. “There’s pretty, pretty strong evidence that these changes — and other changes we’ve observed in fish populations and communities — are related to changes in climate.”
Peter Flood, the research’s lead author, says that the changing environment disrupts some fishes’ natural breeding process.
“That’s changing the timing and availability of resources needed for these fish to grow and also to reproduce,” he said.
Researchers say it’s unclear at this point exactly how the reduction in size will impact the populations.
Flood says that the study could help inform future decisions on fishing regulations or conservation efforts.
“I think it is sort of a starting point to explore these effects and their potential ramifications — shrinking body size could have implications for both recreational and commercial fishing,” Flood said. “You’re getting less fish per unit effort for each line you cast out.”
Environmental groups say that the findings are one of many showing how Michigan is impacted by a shifting climate.
“Our fish having to adapt to warmer waters is just another example of how our ecosystems, and ultimately, our economy and our culture are changing in Michigan,” said Nicholas Jansen, an organizer with the Groundwork Center. “As these fish become less ideal to catch because they’re smaller — everyone loves to catch the big fish, to have that big fishing story — and those become less plentiful. As the fish gets smaller, you’ll also get less food. It’s harder to make a meal out of them.”
Researchers say that as the climate continues to shift, Michigan’s fish species could have trouble adapting to new environments.
“Our winters are getting shorter. They’re getting warmer,” Wehrly said. “It’s going to continue to change, and studies like this are helpful in documenting sort of that biological response to that change.”