Walleye are disappearing from some Northwoods lakes. DNR and GLIFWC biologists explain why.

[00:00:00]Some might call it their favorite game fish. Others would call it spirit food.

[00:00:05]But experts say this famous freshwater fish is under threat.

[00:00:09]>> Walleye are declining in the ceded territories.

[00:00:12]>> And both state and tribal biologists agree it's not going to be an easy fix.

[00:00:17]>> We have not found a magic bullet to address declines in walleye populations.

[00:00:22]>> It's not just we'll drop the harvest, we'll start stocking, it'll come right back. That's not been the case.

[00:00:30]>> In northern Wisconsin, more than 800 lakes are home to walleye. Those populations are managed and monitored by people like John Kabusiek. He's a region team supervisor assigned to walleye at the Wisconsin Department of Natural Resources.

[00:00:44]>> The department has a responsibility to manage um waters in the state. Um but it's but it's a big job, right? It's not something that that we're we're able to take on by ourselves. [snorts] >> The DNR co-manages walleye with the Great Lakes Indian Fish and Wildlife Commission. GLIFWC represents the rights of 11 Ojibwe tribes across Wisconsin, Minnesota, and Michigan to hunt, fish, and gather in the ceded territories.

[00:01:09]That's land that was signed away in treaties with the federal government during the 1800s.

[00:01:15]Mark Lurring is the Inland Fisheries Section Leader at GLIFWC. He said GLIFWC brings a slightly different approach to resource management.

[00:01:23]>> We work with our member tribes that have treaty rights in this area and then we try to infuse culture with our management. You know, there's that science perspective uh that more western science that type of culture perspective and then that tribal culture perspective. And so our job is to try to put those two together.

[00:01:43]>> Each agency surveys lakes and collects population data. Twice a year, they get together to share their findings.

[00:01:49]>> It's a way for us to stay in communication, create these shared data sets that help us answer questions about about fisheries problems we might be seeing and and develop relationships.

[00:01:59]>> Those data sets are some of the largest on walleye in the world and recently they show a concerning trend. A sharp decline in the number of lakes where walleye naturally reproduce.

[00:02:11]Until 2010, that number was around 400.

[00:02:14]>> And that number has dropped in the last 15 years by probably about 30 to 40.

[00:02:19]>> That's nearly a 10% drop, an average loss of two to three lakes a year. For Glyfwic, that's cause for concern.

[00:02:27]>> So tribes talk about seventh generation and protecting things for the seven generations. Even in a 100 years, that that'd be half of our naturally reproducing lakes that are gone and a seventh generation is a much longer time scale than that.

[00:02:40]>> Worse, some biologists are worried that the trend could speed up.

[00:02:43]>> Maybe 2025 through 2040, it's going to be four per year or it might be more than that, you know, we we just don't know.

[00:02:52]>> Despite research, there is no magic bullet solution. In conversations with state and tribal biologists, one theme became clear. Most biologists agree that there's a whole bunch of factors making these walleye populations disappear.

[00:03:05]>> The cause isn't the same in all the different lakes. Many of these lakes, multiple stressors are working at the same time.

[00:03:12]>> And the way these so-called stressors interact is different in every single lake.

[00:03:18]Mark Luring at Glyfwic said one stressor they're looking at is habitat health, especially when it comes to developed shorelines.

[00:03:26]>> Walleyes do well with undeveloped shorelines. When you think of places where walleyes thrive, a lot of us think further north into Canada where there's less development and more connectivity between systems.

[00:03:37]>> The common practice of manicured lawns and smooth sand beaches can cause sediment and fertilizer to leach into lakes. That disturbs areas where walleye lay eggs and creates toxic environments.

[00:03:51]Another stressor, a shift in fish community.

[00:03:55]Both Luring and Kabouciek said in some lakes where walleye have disappeared, unfriendly species have taken their place.

[00:04:02]>> Walleye get along really well with perch, yellow perch, and fairly well with muskies, and less well with largemouth bass, bluegills, and crappies.

[00:04:11]>> Those three species prefer warmer waters. As lakes and streams heat up due to climate change, they'll be favored over walleye, which prefer cooler waters. Kabouciek at the DNR said the problem is so widespread, the agencies face choices in which walleye populations are worth defending.

[00:04:28]>> Versus accepting a shift to what's going to be a different fish community.

[00:04:32]>> Fishing, whether by pole or spear, is also a factor. But biologists disagree on exactly how impactful it can be.

[00:04:41]Luring said often the number of fish that can be sustainably harvested changes from lake to lake based on what's stressing those fish.

[00:04:49]>> There's harvest going on, while development goes on, while potential warming is going on, and fish community shifts are going on.

[00:04:56]>> Based on their data sets, the DNR sets bag limits for anglers, and Glifwic sets limits for tribal spearers and net fishers. The agencies say they design these limits to prevent over-harvesting.

[00:05:08]Kabouciek said in many declining lakes, it's because of a recruitment bottleneck. Basically, young fingerling walleye aren't reaching adulthood.

[00:05:17]>> The fish spawn successfully, eggs are laid, fertilized, they develop, and they typically hatch. But then they abruptly disappear around the beginning of July.

[00:05:25]>> These young walleye aren't being targeted by anglers or spearers.

[00:05:29]Biologists say they're disappearing because of other factors.

[00:05:32]>> It's really cumulative impacts of all of these things together that are affecting walleye populations.

[00:05:38]>> So, what can be done to stop the decline? Both tribes and the state run walleye hatcheries and stock struggling lakes.

[00:05:46]Stocking helps in some situations. For example, when crappie are seen feeding on young walleye.

[00:05:51]>> Stocking allows us in those situations to maintain enough adult walleye until the crappies declined, and natural reproduction of the walleye resumed.

[00:06:00]>> But stocking won't address those underlying stressors. Luring said that could be seen in the 10-year effort to rehabilitate the Menominee chain of lakes.

[00:06:08]>> Tribe stopped harvesting, state stopped harvesting, stocking was taking place, there was addition of some spawning reefs, and we did get the adult populations to come back up, but we still didn't get natural reproduction back.

[00:06:19]>> Luring said once they see a population is struggling, the agencies have to act quickly in order to set new safe harvest limits. For tribal spearing, Glyphic can adjust bag limits annually based on last year's data. But for rod fishing, it takes the DNR 2 to 3 years to make an adjustment. This past May, the DNR began looking into changing its rules. So, in an emergency, when a lake is really struggling, they could more quickly drop the bag limit to just one walleye a day.

[00:06:49]Luring testified that would go a long way to improve co-management.

[00:06:53]>> We can pull together cooperative rehabilitation plans sooner, and also prevent that population from declining further.

[00:07:02]>> Luring said what biologists need is support in studying and protecting at-risk walleye populations. Many of those populations live in lakes surrounded by private property, which makes them inaccessible to biologists.

[00:07:16]Lakeside property owners can protect their local walleye by reaching out to DNR or Glyphic biologists.

[00:07:22]>> There needs to be a collaborative effort on keeping our shorelines natural, providing good conditions for walleye populations. We can do a good job of educating people about what the best practices are, how we can make conditions good for walleye, and I think that can help prevent further decline. That might mean some things need to change like how we think about our shorelines. But Loring said that might just be what the walleye need to survive.

[00:07:51]>> I think it's a difficult time and a learning time for us. You know, as humans we're learning how to be in a place where walleye are and to do it well. And I think it's an opportunity for us to to make some changes and to do things that work better for walleye going forward.

[00:08:06]>> For the Northwoods, I'm Koji Taylor for NewsWatch 12.