Climate change hurting state’s fish
No Wisconsin angler I know would prefer a future with fewer walleyes, brook trout and muskies.
But that's where we're heading, according to fisheries experts. In fact, the declines have already started.
The primary reason is a force as charged as it is amorphous: climate change.
Warmer conditions simply don't favor cold and cool water species.
But while data clearly shows the planet is heating up, lingering denial and a general lack of effective action are painting an ever bleaker forecast for the state's iconic fish.
We're not alone in the Badger State. The problem is of global proportions.
And of course it doesn't only affect fish.
But it's such a critical issue the American Fisheries Society has focused much of its 2020 conference on the topic. Due to the coronavirus pandemic, the Sept. 14-25 gathering is being held online.
The organization, celebrating its 150th anniversary this year, is the world's largest and oldest fisheries science group. Its members range from federal and state fisheries employees to university researchers.
On the first day of its 2020 conference the AFS joined 110 aquatic scientific societies representing more than 80,000 scientists across the world to sound a climate change alarm.
The fisheries groups Monday called for "drastically curtailed global greenhouse gas emissions to avoid the worst impacts of a warming climate to fish and aquatic ecosystems."
The harm isn't restricted to fish and wildlife. Human health, jobs and global economies are also at stake, according to the scientists.
“Swift and resolute action by governments and by individuals to reduce emissions is essential to halt irreversible impacts to freshwater and marine ecosystems, fish, and fisheries from climate change," said AFS president Scott Bonar in a statement. "We must act now to safeguard our drinking water, food supplies, and human health and wellbeing."
Bonar said the grim predictions were not theoretical.
"They are affecting us now and failure to act will imperil future generations,” he said.
While nature is resilient and systems and species can adapt over time, the changes may not be desirable.
Anglers in Wisconsin, for example, would likely rather keep walleyes and muskies in their northern lakes than have them replaced with warm water species.
But recent years have already shown a reduced level of walleye recruitment, or survival of young fish, and a resulting drop in sport fishing harvest.
Several studies have linked the downturn in natural walleye reproduction to warming lake conditions.
Although in some cases exploitation has likely been too high, even in waters where sport and tribal harvest has been prohibited, such as the Minocqua chain, no or very low numbers of walleye fry have been documented.
Walleyes accounted for 25% of the Wisconsin sport fishing harvest in 1990, according to a University of Wisconsin study. By 2017, it had declined to 9% as anglers took home more panfish, bass and other species. This "harvest switching" was in large part driven by the declining walleye population, according to the researchers.
In the state's streams, the native brook trout has long been a favorite species. But even under a moderate warming scenario, 94% of brookie habitat is projected to be lost by 2050, according to a Wisconsin Department of Natural Resources study.
Our state's waters are changing, and it isn't good for some of our favorite fish.
"Some of Wisconsin's most cherished fish are already experiencing negative impacts of climate change, with more damage coming,” said Max Wolter, president of the Wisconsin Chapter of AFS.
Wolter said the forecast includes both warmer temperatures and changes to precipitation patterns. Since our native fish evolved over thousands of years, even what might seem like a small change can disrupt the timing of critical events in the reproduction chain.
"We have already seen climatelinked declines in natural reproduction of walleye which translates to less adult walleye available to anglers," Wolter said. "Other coolwater fish like muskellunge are in the cross hairs too. We cannot simply stock more fish or change angling regulations and hope these problems will go away.”
Human history has many examples of great initiatives forged in dark times.
In the conservation arena, the Migratory Bird Treaty and Wildlife Restoration Act were both started when many native species were on the brink of extinction but subsequently recovered.
Maybe in 2020, a year in which a pandemic reminded us how closely connected the world is and which will likely see a vaccine produced in record time, scientists such as those with AFS will help generate the response needed to deal with an even bigger plaque.
"We need to think about what we're passing on," said Wolter, who has a 4year-old son. "If we don't make changes, the opportunities we had definitely won't be there for our kids and grandkids."