MADISON, Wis. (SPECTRUM NEWS) — At D&S Bait and Tackle, They've been helping people get out and catch fish for nearly four decades.

“We're fortunate as far as walleye fishing goes here in the state of Wisconsin,” said Gene Dellinger, owner of the east Madison shop for the past 28 years.

However, Dellinger hears people talk about with walleye, is that they're getting harder to find up North.

“That for the last several years has been a topic of conversation is that the walleye fishing isn't what it once was and it's problematic,” Dellinger said.

Anglers, biologists and tribes have noticed that decline in walleye is something over the past 10 to 15 years.

“No real smoking gun has been figured out as to why walleye have been declining and historically harvest hasn't really been thought of as a factor in those declines,” said Holly Embke, a biologist and PhD student at the Center for Limnology at UW-Madison.

Now researchers like holly Embke have released a report that could give some answers.

Embke said that while harvest numbers have remained the same for decades, the walleye population isn't recovering as quickly as it used to year after year.

“Overtime these populations are just not able to reproduce and keep up in the same way that they once were able to,” she said.

Embke worked with fellow researchers in the Center for Limnology as well a biologists with the Wisconsin Department of Natural Resources and researchers at other universities to do the work.

In all the research took five years, looking at walleye populations in the northern third of the state from 1990 to 2017.

They took a production approach, meaning they looked at how fast populations recovered versus how fast they were harvested.

Embke compares it to a bank account. She says it's like a person taking out the same amount every year, but the amount going back into the account slows down.

“Over time you're just kind of disproportionately removing larger and larger proportions of walleye or money from the bank every year,” Embke said.

The research doesn't suggest that the harvest itself is the problem.

In 1990 biologists evaluated the management system thoroughly and it was working. They reinforced harvest regulations. However, since that time walleye populations in many northern-Wisconsin lakes have decreased by as much as 35 percent.

Steve Carpenter, director emeritus of the Center for Limnology and co-author of the study said the regulations worked for a long time.

“And then they stopped working. Over the last couple of decades, there began to be walleye recruitment failures scattered around the state,” Carpenter said in a press release.

Embke said factors like warming lake temperatures, decreasing habitat, and invasive species have taken their toll. Ultimately keeping walleye populations in those lakes from recovering as quickly as they were being harvested. Leading to a general over harvest of the lakes.

Embke said she doesn't think anglers should panic right now, and the researcher isn't suggesting any changes yet.. However she hopes the research and the new approach to examining these populations will help stabilize walleye in the future.

“Start to incorporate that into the management framework that that gets considered moving forward,” Embke said.

Dellinger says it's disappointing to see populations fall. Both for him and people at his shop who will go up north for a fishing getaway.

“It's alarming I guess to a certain extent especially in the northern part of the state where a large part of their business is tourism that used to be generated by fishermen and is less so because the fishing is less attractive than it used to be,” Dellinger said.