DNR fisheries biologist says Lake Winnebago sturgeon population supports spearing but invasive species pose long‑term risk

Margaret, a Department of Natural Resources (DNR) fisheries biologist based in the Oshkosh office, told an audience that the Lake Winnebago system is among the premier lake sturgeon populations in the United States and supports a winter spearfishing season that saw about 1,500 harvested sturgeon this year. "We speared 1,500 this year," she said, contrasting that number with a six‑fish quota at Michigan's Black Lake.

She said fisheries scientists use mark‑and‑recapture methods and permanent microchip tags to estimate population size and track individuals. "We can take about 5 percent of their population every year without concern," Margaret said, identifying a 5% exploitation threshold the DNR uses to evaluate sustainable harvest levels.

To generate population estimates and monitor exploitation, Margaret described tagging work at Princeton and other spawning sites: staff and trained volunteers net spawning sturgeon, measure and sex them, and implant passive microchips behind the pectoral region that can be read on recapture. She emphasized that people who spear sturgeon must register the harvest with a DNR agent before the end of the day so the agency can record weight, check for tags and collect biological data.

Margaret credited a combination of regulation and habitat work for bringing exploitation below the 5% target since reforms in the 1990s and 2000s. She described improvements to spawning habitat — such as adding larger cobble and preserving fast‑flowing reaches on the Wolf River and tributaries (sites she named include Bamboo Bend and Chiachton) — and said those habitat improvements help natural reproduction and reduce reliance on stocking.

The DNR also runs a citizen volunteer program called Sturgeon Guard that monitors spawning sites in Princeton, Berlin, Eureka and Astridge. Margaret said the program's volunteers both help deter disturbance and educate visitors: "Sturgeon Guard is a program. It's a citizen led program, where they will go and they will kind of be at those spawning sites making sure that fish no one's disturbing the fish," she said, and invited volunteers to sign up.

Margaret warned, however, that invasive species remain an important uncertainty. She singled out round goby as a primary concern because gobies feed on eggs: "With round goby on the bottom, [spawning sites are] a buffet," she said, noting that short‑term effects could include more food for adults but that egg predation could reduce recruitment in ways that would not be detectable for many years.

She also described interstate restoration work: biologists take eggs from a small number of females during Winnebago spawns and raise juveniles for restocking elsewhere. Margaret said a recent request called for about 1,500,000 eggs, taken from roughly six females, and that partners in Ashland and on the Milwaukee River use Winnebago eggs in their stocking programs.

Margaret closed by noting the long time horizon for sturgeon recovery — fish reach maturity at 10–20 years and population responses can take decades — and by encouraging members of the public to join the Sturgeon Guard program or sign up for her email updates on water temperatures and spawn timing. No regulatory action or vote was taken at the presentation; the session was an informational briefing and question‑and‑answer period.