Global warming could mean fewer fish for sport fishing, more die-offs across US

Andrew Rypel, a professor of wildlife, fish and conservation biology at the University of California, Davis with a walleye he caught in Sanford Lake, Wis. (Photo: Courtesy Andrew Rypel)

Global warming is putting lake fish in hot water, with worrisome possibilities for many species, as well as the nation's fishermen and the $115 billion sport fishing industry that employs as many as 820,000 people. 

A study published in the journal Nature Climate Science Monday found at least a 100 fish die-offs in Wisconsin between 2004 and 2014 were strongly linked with warmer summer temperatures fueled by climate change. Already, some species, such as walleyes and cisco, are experiencing declines because of warming water temperatures. 

And it's only going to get worse if humans don't act. The die-offs in Wisconsin’s lakes are expected to double by mid-century and quadruple by 2100 and there could be significantly more fish die-offs as global temperatures increase.

The concern extends far beyond Wisconsin. Scientists and sport fishing officials across the United States are worried that global warming could have grave consequences for local ecosystems, as well as sport fishing industries. That includes everything from marinas, fishing guides, tackle shops, restaurants, hotels and fishing gear manufacturers, according to the American Sportfishing Association. 

“It supports 22,000 jobs in our state. We’re talking about an effect that has a direct economic impact on a state with a big outdoor tourism economy,” said Andrew Rypel, a fish biologist at the University of California, Davis and an author on the paper.  

Wisconsin is a bellwether state because it's the third most popular destination for anglers to travel to, according to the sport fishing association, after Florida and Michigan. Sport fishing is a $2.3 billion industry in Wisconsin. 

The Wisconsin findings are based on a particularly rich dataset that's been collected by the state over many years. It was analyzed by a group of biologists, ecologists and fisheries scientists. They found that warmer temperatures could mean trouble for species common in these lakes, such as bluegill, walleye, largemouth bass and northern pike.

The researchers' findings match the state's, said Alexander Latzka, a fisheries biologist with Wisconsin's Department of Natural Resources.