MENASHA, WI (WTAQ-WLUK) – A study on a proposed electrified barrier for round gobies at the Menasha lock showed promising results, but the need for additional study means the lock will likely not open again until at least 2023.
The Menasha lock, which connects Lake Winnebago and Little Lake Butte des Morts, has been closed since 2015 to prevent the round goby from spreading to Lake Winnebago. The Fox River Navigational System Authority wants to install an electric barrier, and then reopen the lock.
“We want to get this open. And one thing we have learned is that we need to be methodical. There’s a fair amount of science to this. And we want to make sure we are doing our due diligence right now so that everything we do in the future is built on a solid foundation because we’re just as concerned about the biological ramifications as the DNR is,” said FRNSA CEO Jeremy Cords.
The system authority hired a consulting firm to determine if the barrier would prevent the fish from entering the lock. Electronic voltage would pulse near the bottom of the concrete where the gobies like to swim, pushing them away or immobilizing them. The system would then use changes in water velocity to flush out the lock channel and prevent the gobies from getting into Lake Winnebago. And, that was successful, according to the report presented Tuesday.
“It was found that an energy density of about 200 J/cm3 immobilized all lengths of adult Round Goby used in the experiment,” the technical memo from Kleinschmidt Associates states.
The electrified field would be about 34’ wide, 100’ long, and 12-13’ deep.
However, the DNR has also requested data on if the barrier would work with juvenile and larval gobies. Researchers have had problems getting enough of that age fish – either by collection in the wild or reproduction – and haven’t been able to do that part of the work.
“The full scope of work cannot be completed at this time because the studies are incomplete,” the memo states.
The next phase of the study on the younger fish would include collection in June and July, then performing the experiments. Those results could be done by fall, said researcher Jason Kent.
However, the FRNSA board has not approved that phase of the work, and did not take any action Tuesday to approve it. The approval is all but certain, however, and will come relatively soon, Cords said.
It hasn’t been determined when a final plan will be presented to the DNR. Once submitted, the state’s review is expected to take about two months. Once final approval is given, it would take nine-to-14 months to construct the $3 million barrier.
Even if the barrier is installed and is successful, the Menasha lock is just one of 60 entry points into Lake Winnebago.
Separately Tuesday, UW-Green Bay biology professor Patrick Forsythe told the FRNSA that 470 round gobies were found at multiple sampling sites along the Fox River in 2020, but none in Lake Winnebago. That figure is lower than the number collected in 2019, despite adding more sampling sites in 2020.
Cords credited boaters and anglers for taking the appropriate steps to help prevent the spread of the gobies from the river to Lake Winnebago.
