Author Archives: Packerland Team

Diets of Larval Walleyes in Northern Wisconsin Lakes

Nathan Jaksha1, Daniel Isermann2, & Daniel Dembkowski1

University of Wisconsin-Stevens Point1, USGS-Wisconsin Cooperative Fishery Research Unit2


  • Walleye are an important species in Wisconsin that support both recreational hook-and-line and tribal spear fisheries.
  • Walleye recruitment has declined in some lakes that previously supported natural recruitment yet has remained stable in other lakes.
  • Recent studies suggest that a recruitment bottleneck may be occurring at or before the larval stage in lakes exhibiting declines in natural recruitment.
  • Reasons for the contrasting trends in recruitment among populations are unclear, as are mechanisms underlying the recruitment bottleneck in lakes with declining recruitment.
  • Differences in prey availability among lakes with different recruitment histories could contribute to the observed trends in recruitment.
  • Assessment of larval walleye diets from lakes with different recruitment histories could provide important insight to the role of prey resources in explaining trends in walleye recruitment in Wisconsin lakes.
Photo of an adult walleye sampled by the Wisconsin DNR


Describe diet composition of larval walleyes in northern Wisconsin lakes displaying two different recruitment histories: sustained natural recruitment (S-NR) and declining natural recruitment (D-NR).

Methods – Sampling

  • Larval  walleye sampling occurred during 2016 & 2017 on 13 lakes
    • Five of these lakes were resampled in 2018
  • Sampling started mid-May each year
    • Continued at 7-10 d intervals until early June
    • Surface temps = 11-16˚C
  • Larval walleyes were collected using a 1,000-µm mesh conical ichthyoplankton net.
    • Towed at surface (5 min) at both nearshore (within 100-m) & offshore locations (≥100-m) at night
  • Percid larvae identified to species using dichotomous keys
    • Random subset selected for genetic verification of visual species identification using PCR techniques

Methods – Diets

  • Gut contents of each fish were removed and diets were quantified using mean percent composition by number of individual diet items.
  • Zooplankton items classified to order for adult copepods and genus for cladocerans
  • Larval fish encountered in diets identified genetically using qPCR techniques
Magnified image of a zooplankton (Daphnia spp.) diet item
Magnified image of a larval Walleye

Results – All Lakes

  • Larval walleye collected from 6 S-NR lakes and 4 D-NR lakes (diets summarized in Table 1).
  • Guts were removed from 115 larval walleyes (mean TL = 11.4 mm; range = 6.4 –22.0 mm).
  • 27% of diets (31 of 115) were empty
  • 37% of diets (42 of 115) contained larval yellow perch
  • 16% of diets (18 of 115) contained zooplankton

Table 1. Mean percent composition by number and counts of prey items observed in larval walleye diets from all lakes combined.Search:

Daphnia spp.15.041
Calanoid Copepods1.83
Cyclopoid Copepods5.816
Bosmina spp.0.53
Larval Fish63.349

Showing 1 to 6 of 6 entries

Results – S-NR vs. D-NR Lakes

  • S-NR Lakes = 86 larval walleye (diets summarized in Table 2)
    • Larval walleye mean length = 11.3 mm (range = 6.5 -22.0 mm)
    • 38 % of diets (33 of 86) were empty
    • 31% of diets (27 of 86) contained larval yellow perch
    • 20% of diets (17 of 86) contained zooplankton
  • D-NR Lakes = 29 larval walleye (diets summarized in Table 2)
    • Larval walleye mean length = 12.4 mm (range = 7.8 -21.0 mm)
    • 28% of diets (8 of 29) were empty
    • 52% of diets (15 of 29) contained larval yellow perch
    • 3% of diets (1of 29) contained zooplankton

Table 2. Mean percent composition by number and counts of prey items observed in larval walleye diets from S-NR and D-NR lakes.

Diet Item% CompositionCount% CompositionCount
Daphnia spp.19.1404.81
Calanoid Copepods2.530.00
Cyclopoid Copepods8.1160.00
Bosmina spp.0.730.00
Larval Fish60.13471.415


  • Larval yellow perch were the dominant prey item for larval walleyes in lakes exhibiting both sustained and declining natural recruitment.
    • Extent of piscivorymuch greater than previously assumed
  • In general, larval walleyes in S-NR lakes consumed a greater diversity of prey items and more zooplankton than larval walleyes in D-NR lakes.
  • Further statistical analyses required to determine if diets and prey availability differed between S-NR & D-NR lakes.


  • This study was funded by the Wisconsin Department of Natural Resources through the Fisheries Analysis Center at the University of Wisconsin-Stevens Point.
  • Jason Gostiaux
  • Walleyes for Tomorrow: Research Fellowship

U.S. Fish and Wildlife Service Seeks Public Input to Increase Access to Refuge System Lands

As part of its ongoing effort to increase public access on federal lands, the U.S. Fish and Wildlife Service today announced (news release attached) it is seeking the public’s assistance to develop a list of its managed lands that would benefit from new or increased access routes. 

On March 12, 2019, President Donald Trump signed into law the John D. Dingell Jr. Conservation, Management, and Recreation Act (S.47, the Dingell Act), which directs the Service and other federal land management agencies to develop a priority list of lands that have significantly restricted or no public access where that access could be improved. The public is encouraged to identify national wildlife refuges, fish hatcheries and other lands managed by the Service that meet the complete criteria. 

Comments will be accepted over a 30-day comment period from February 10-March 11, 2020. 

Some of the criteria for nominated lands include: public lands must be managed by the Service and 640 contiguous acres; have significantly restricted or no public access; and be open under federal or state law to hunting, fishing, or use of the land for other public recreational purposes. 

For additional information and a full list of required criteria for consideration as specified by the Dingell Act, visit:

Commenters are encouraged to review the required criteria and include additional information as to why the parcel should be on the Service’s priority list. Once the comment period closes the Service will evaluate the nominations to determine which lands meet the requirements and considerations specified by the Dingell Act.

Expanded Assessment of Recruitment Bottlenecks for Age-0 Walleye Sander Vitreus in Northern Wisconsin

A Thesis Submitted in partial fulfillment of the requirements of the degree
College of Natural Resources UNIVERSITY OF WISCONSIN
Stevens Point, Wisconsin

Many northern Wisconsin lakes that historically supported naturally-recruiting walleye Sander vitreus populations have shown declines in recruitment over the last 10-15 years. Previous research conducted on four northern Wisconsin lakes suggested a recruitment bottleneck was occurring before mid-July in lakes with declining walleye natural recruitment. Effective management of walleye populations involves understanding these recruitment bottlenecks, as potential management solutions may vary in relation to when and why this recruitment failure is occurring. To further assess these recruitment bottlenecks, I expanded on the previous assessment to determine if: 1) timing of a recruitment bottleneck for age-0 walleyes was consistent among lakes with declining
recruitment; 2) abiotic and biotic metrics differed between lakes with declining (D-NR) and sustained (S-NR) walleye recruitment, with a specific focus on the abundance of edible zooplankton and 3) catch-per-effort (CPE) of larval and post-larval walleyes can be used to predict the presence, absence, and relative strength of walleye year-classes indexed by standard fall electrofishing conducted by the Wisconsin Department of Natural Resources and the Great Lakes Indian Fish and Wildlife Commission.

Walleye are Spawning – Thesis

Hadley Boehm was the grad student who did the walleye research under Dan Isermann last year. She graduated, got a job with the Minnesota DNR, and then finished her thesis, a copy of which is attached. The research is continuing….

The short version is: Walleye are spawning, then the fry are showing up in some lakes, and not showing up in other lakes. No fry = no YOY in fall. And nobody knows why.

Click here to read Thesis


image003This report contains length distribution of Walleye captured during 2014 spring electroshocking on the Fox, Oconto, Peshtigo and Menominee Rivers.

Charts also show active year classes.

Walleye stocks in southern Green Bay were decimated during the early to mid-1900s by habitat destruction, pollution, interactions with invasive species, and from over-exploitation. Following water quality improvements in the early 1970’s, the Wisconsin Department of Natural Resources began to stock fry and fingerlings to rehabilitate the Walleye population.

Stocking began in the Sturgeon Bay area and later expanded to include the lower Fox River (downstream from the DePere Dam). This stocking (fingerlings and fry) was so successful in southern Green Bay and the lower Fox River that it was discontinued in 1984 to allow surveys to determine if substantial natural reproduction and recruitment was occurring.

However, stocking in the Sturgeon Bay area resumed in 1994 and continues with a mix of fry and fingerling being stocked to augment the population. The total number of number of Walleye stocked in Wisconsin waters of Green Bay has varied by location and year with over 70,000,000 fry and 4,500,000 fingerling stocked into Green Bay and the Fox River since 1973.

Click Here to see full report along with year classes of walleye that are in Green Bay

WDNR Fisheries staff with tagged walleye

We look forward to working with our local DNR staff in not only increasing habitat, but education about the walleye as well with work being done at the Peshtigo River

Photos of
• Anglers lined up in the lower Peshtigo River in the spring.
• A big female. Look closely at the base of the dorsal and you can see a green floy tag.
• Closer up of a floy tag.
• 2012 survey on the lower Peshtigo River. Left to right WDNR fisheries staff Ron Rhode, Tammie Paoli, Rod Lange, Brad Ryan.
• Crew and shocking boat on the lower Peshtigo.
• A walleye with lymphocystis (and a yellow floy tag). In the spring, we get quite a few calls about fish having warty growths on them. Lymphocystis is a viral disease that is seldom fatal that seems to peak in the spring during colder temps and spawning stress…

March 11, 2016 WFT Green Bay Banquet

We are a 501c3 non-profit organization that raises money locally with 100% of all money being raised being spent here in Northeast Wisconsin.
Local projects have included:
• Develop rod & reel loaner program for Boys & Girls Club
• Take special needs kids on a fishing day
• Support and supply rods & Reels for kid’s education seminars on fishing
• Purchased $5,000 micron microscope for DNR for fish disease prevention
• Assisted in building handicap fishing pier in De Pere
• Built spawning reef outside of the mouth of the Fox River by Bay beach
• Built spawning reef along the East shore the bay of Green Bay
• Developed habitat on west shore Peshtigo River for walleye spawning.

Our banquet is March 11, 2016 at the Stadium View and your support is both greatly appreciated and needed in order to carry on our volunteer work. We will include promotional items and display of posters or brochures provided during the event.

Get Your 2016 Tickets

If you have any questions, Please give me a call at 920-826-5901.

Peshtigo Flowage – Walleye Spawning Reef

PESHTIGO – Generous funding from several partners and a window of opportunity during a dam repair allowed DNR and partners

to build a walleye spawning reef in the Peshtigo Flowage below Potato Rapids Dam.

The project involved adding 300 tons of glacial stone to create a walleye spawning reef to promote natural reproduction of walleye. The project became a possibility when water levels were drawn down on the Pestigo Flowage between May and October 2012 to replace the Highway 41 bridge and complete maintenance to the dam in Peshtigo. The drawdown not only made building the spawning reef possible, but greatly reduced the cost.

Construction took place during the first weeks of August. A majority of funding was provided by Walleyes for Tomorrow ($7,000), Wisconsin Public Service ($4,000), and the Porterfield Sportsman’s Club ($3,000). Significant natural reproduction of walleye is expected once the adult population has been re-established.

– Chip Long, senior fisheries biologist, Peshtigo

Project: Fox River Reef, Green Bay, WI

Local team works together to create spawning habitat

By Kevin Naze Press-Gazette Correspondent Reprinted courtesy of the Green Bay Press Gazette

By Kevin Naze
Press-Gazette Correspondent
Reprinted courtesy of the
Green Bay Press Gazette

Terry Lychwick had the idea. Chester and Michael McDonald provided the manpower.

But when it came time to “show me the money,” the Green Bay chapter of Walleyes For Tomorrow came through with $12,000 to help put 73,000 square feet of spawning habitat on the frozen water of Green Bay last month.

As the ice melts, nearly 4,000 tons of small rock will fall through, providing a place for walleyes to lay eggs in a 2- to 3-foot-deep area that previously was nothing more than a flat, hard clay bottom.

In addition to possibly attracting hundreds of spawn-minded walleyes each spring, the reef could help protect a developing wetland complex along the bay shore.

The McDonalds provided labor and equipment to install the rocks, as well as more than 50 huge boulders. They placed the largest stones between two long, irregular, rock breakwaters that were constructed last fall.

Lychwick, a Department of Natural Resources fisheries biologist in Green Bay, said one of the conditions of the McDonalds’ South Bay Marina permit two years ago was they had to provide fish and wildlife habitat.

A number of bayshore bird species likely will use the exposed part of the boulders as rest areas, he said, while fish will use what’s under water as cover.

“Fish guys might only think fish, and bird guys might only think birds, but this whole project addresses a lot of different wildlife issues,” Lychwick said.

Dan Farah of Green Bay is the local WFT chapter chairman.

“It’s an excellent fishery, and we’re just trying to do what we can to make it even better,” Farah said.

The additions of another manmade spawning area in the bay might take some of the pressure off the limited amount of good spawning habitat in the river itself, he said. That could add up to better production.


Chester and Michael McDonald provided labor and equipment to install almost 4,000 tons of 3- to 6- inch rock on the ice of Green Bay near the South Bay Marina East of the Fox River mouth last month. As the ice melts, the rocks will sink, providing a new spawning habitat for walleyes

Besides the Green Bay chapter’s donation, another $10,000 came from the FishAmerica Foundation. That included money from the U.S. Fish and Wildlife Service, FLW Outdoors (formerly Operation Walleye) and the Wal-Mart RCL Championship held in Green Bay in fall of 2001.

Farah said the reef was supposed to be in place two years ago, but poor ice conditions prevented heavy equipment from getting out safely.

This was the group’s second spawning reef, having funded one 1,000-feet long by 30-feet wide in the late 1990s north of the University of Wisconsin-Green Bay near Joliet Park.
In the 12 years since Walleyes For Tomorrow formed, it has helped raise $850,000 for habitat and enhancements for Northeast Wisconsin walleyes.

The group has been a success ever since its first banquet–in North Fond du Lac–raised nearly $18,000. Some 450 people attended that 1991 event.

WFT has grown to include chapters in 11 parts of the state, including the Fox Valley, Manitowoc and New London.

The group’s mission is to work with other clubs, agencies and the DNR to improve the quality of walleye and sauger fishing.

In 1995, WFT became a participant in the DNR’s walleye management planning committee. That same year, it began to use portable “Walleye Wagons” as mini-hatcheries to supplement stocking in some state rivers and lakes.

Since than, it has tackled dozens of projects, from stocking 1,800 walleyes in the rehabilitated Silver Lake in Manitowoc County to providing funds for retired conservation wardens to discourage over bagging during spring walleye runs on the Wolf River.