Researchers in 2014 were hopeful that Wisconsin walleye would be safe from climate change. The species typically flourish in Wisconsin’s tepid temperature ranges, meaning that the fish generally has done well in the state. Unfortunately, in 2022, the walleye has started to feel the heat of climate change.
Walleye and countless other species rely on the transitionary time between winter and spring for young to develop. However, due to climate change’s impact, there is no longer a smooth transition from winter to spring as variable temperature may be preventing fry from fully maturing.
The declining population may cause more harm to locals than paying extra for walleye from out of state. Instead, Wisconsin’s tribes are losing an important aspect of their culture. Furthermore, the state will suffer economic losses as fishing brings in more than $2 billion annually, according to a Wisconsin Public Radio broadcast.
So far, warming waters have caused an increase in bass populations which indicates why walleye are missing and marks the entry of a predator. Bass prefer clearer, warmer waters with plentiful vegetation. In contrast, walleye enjoy murkier water with little vegetation.
Warmer waters don’t necessarily mean anything for Wisconsin walleye, as the fish does fine in tepid climates. However, bass populations growing in ideal environments may mean that walleye have a new predator to be warry of. For the most part, warmer water isn’t the issue; daily volatile temperature changes are damaging population sizes.
Some researchers believe that the recent decrease in population is not the predecessor to doom that others have interpreted.
“Climate change usually affects species ranges on the edges, because they’re going to go farther north or farther south or higher up the peaks,” said Andrew Fayram, study author and monitoring coordinator with the state’s Department of Natural Resources. “We could not be more smack in the middle of walleye country.”
For the study, published in the journal Aquatic Ecosystem Health & Management, the researchers assembled data on the success of juvenile walleye year classes between 1997 and 2006. They built a model to relate it to 50 years of climate data on maximum temperatures, minimum temperatures and precipitation.
The results predict that climate may have boosted the number of juvenile walleye across the state that survived their first year by about 3 percent from 1950 to 2006. “That’s a small change not noticed by anybody,” Fayram said. “Fisheries biologists, anglers — nobody is going to see that.”
Not only is the walleye’s status under debate some argue that even if they were decreases in population, nothing needs to be done about it.
“There are people who think they (bass) are the devil incarnate, and there are other people who think this is just how it goes,” Fayram said. “It’s actually shockingly controversial.”
The simplest explanation is that the bass in those lakes are eating up young walleye, but it might not be that simple. It’s even possible that climate change is influencing the balance even if it isn’t directly affecting walleye. It could be shifting the competitive advantage by nudging some other part of the system like bass, sculpin, or who knows what.
“Ecosystems are complex, so it might be something that no one’s even looked at,” Fayram said.
The past climate data came from the Wisconsin Initiative on Climate Change Impacts. The same group has also assembled projected temperatures and precipitation well into the next century. The researchers could use those projections to model future effects on walleye. However, the neutral results in the past has told the researchers they weren’t likely to find anything shocking about the future.
“Walleye are not going extinct in Wisconsin, I don’t care what you throw at it,” Fayram said. “They might go higher, they might go lower, there might be places that are less suitable, more suitable. No government official is going to get elected or thrown out of office over this because it’s going to be subtle.”