MADISON, Wis. – The Wisconsin Department of Natural Resources (DNR) today announced the agency identified a potential issue with a disproportionate amount of female hatchery-reared extended growth walleye.

The DNR conducted a preliminary analysis of hatchery-reared extended growth walleye sex ratios in 2019, which led to more in-depth research in the fall of 2020, including additional walleye from both the Art Oehmke and Governor Thompson fish hatcheries for histological (studying of the tissues) sex determination.

Although sex was unable to be determined in all samples, these preliminary investigations indicated hatchery-reared extended growth walleye showed sex ratios favoring females. Surveys of naturally reproduced walleye generally show sex ratios closer to a one-to-one male to female or ratios skewed towards males. Currently, there is no evidence to suggest that skewed sex ratios exist in other hatchery-reared species.

DNR Investigating Cause

As a result of these findings, the DNR will conduct additional histological sex determination testing, a comprehensive review of hatchery practices, and an examination of more survey and past stocking data to better understand this issue and the extent of unbalanced sex ratios in hatchery grown walleye. An additional examination of naturally reproduced walleye sex ratios will also be conducted.

Although the cause of this sex ratio imbalance is unknown, DNR staff and other partners have initiated consultations with topic experts and have begun reviewing relevant studies. Additional examinations of hatchery extended growth walleye will be conducted at multiple facilities in 2021.

Since the Wisconsin Walleye Initiative began, over 800,000 hatchery-reared extended growth walleye have been stocked annually into waterbodies across the State. Before the initiative, most stocked walleye were either fry or small fingerlings. It is unknown whether an uneven sex ratio exists in hatchery-reared fry or small fingerling walleye, which the DNR will also investigate.

The DNR will continue to raise walleye while conducting its investigation. Results will be shared and posted to the DNR’s Wisconsin Walleye Initiative webpage after the investigation.

For more information:
Contact: Lori Tate, Fisheries Management Section Chief 
Lori.Tate@wisconsin.gov or 608-400-1850
Dave Giehtbrock, Fish Culture Section Chief 
David.Giehtbrock@wisconsin.gov or 608-345-9853

Amos Melton and Larry Damman have first year success coaching the Shell Lake and Spooner High School Fishing Clubs. Spooner fielded two 4-man teams for their first competition on Bone Lake, Polk County and finished 4th and 10th on gamefish and 7th and 15th on panfish out of 71 teams.

Shell Lake team didn’t place at Bone Lake but narrowly exacted revenge by beating Spooner 183 points to 182.25 for The Battle on the Bay at Ashland for an 8th place finish.

Both schools are excited about competing in the upcoming state tournament at LaCrosse.

Competitions are sanctioned by the Wisconsin Interscholastic Fishing Association.

Friends Into Spooner Hatchery (FISH) is excited to be sponsoring two high school fishing teams from the area. “It’s a perfect match for our mission to promote environmental education,” stated Larry Damman, FISH President and one of the high school fishing team coaches.

To learn more about FISH and to become a member, explore our website or contact us.