Used in some states for algae control in ponds, grass carp, a supposedly sterile Asian carp species, have been in Lake Erie for more than 30 years.
Now, Marc Gaden, communications director and legislative liaison with the Great Lakes Fisheries Commission, said eggs and signs of grass carp reproduction have been found in Ohio waterways.
Additionally, increased surveillance and efforts to remove them have revealed fertile, mature fish for the first time in 2021. Electrofishing and nets are being used on the US side in the Sandusky, Maumee, Cuyahoga, Grand, and Huron Rivers to trap them. Four grass carp were found in the Grand River, of which one was fertile. One fertile fish was found in the Huron River too. Hundreds of sterile fish were captured in the other rivers as well.
“Part of the issue is we don’t know if we’re on the leading edge of an invasion, whereas they haven’t reached a critical mass and are expanding, or are seeing signs of reproduction because we’re looking,” Gaden said.
“The idea is if they can remove 400 per year, the hope is the establishment can be prevented,” Gaden said.
In Ontario and the US, Asian carp surveillance relies on eDNA searches to look for the DNA of a species in the water. While not foolproof, it provides a good indicator that the species or remnants of it, was present.
No eDNA has been found in Ontario waters of Lake Erie since 2018.
Gaden remains positive establishment can still be averted. “We feel we have the techniques. There are still relatively small numbers.”