Survey: Grass carp present in low numbers in Sandusky River

(Photo courtesy of John Hageman)

The good news about grass carp in the Sandusky River is that they seem to be few in number so far; the bad news is that they are there at all.

That may be the take-home message from a recent intensive, multi-agency survey of the lower river at Fremont.

The research crews used several electrofishing watercraft, gill nets, and fyke nets to collect adult and juvenile carp, collecting eight fish. Although present in the system, grass carp populations are considered to be low, and this recent work reinforces this conclusion. A large-scale sampling project is set for 2018 as part of a structured and measured approach to better understand and address grass carp in Lake Erie, the Ohio Division of Wildlife said.

The goal is to allow natural resource agencies, working through the Great Lakes Fishery Commission, to collaboratively develop science-based management approaches and evaluate the effectiveness of different actions and strategies.

The research crews included members of the Ohio Division of Wildlife, Michigan Department of Natural Resources, Department of Fisheries and Oceans Canada, U.S. Geological Survey, New York Department of Environmental Conservation (DEC), and the University of Toledo, in conjunction with aquatic invasive species sampling in Sandusky Bay by the U.S. Fish and Wildlife Service.

The grass carp is an invasive species in the Great Lakes region and is one of four species commonly identified as Asian carp. All species of Asian carp do not have the same negative ecological effects, however, and grass carp present significantly different risks to the Lake Erie ecosystem than the highly invasive bighead carp and silver carp.

An adult grass carp commonly weighs more than 20 pounds and can grow up to 48 inches in length. The fish are primarily herbivorous, consuming large quantities of aquatic vegetation, and they can affect fish communities primarily through habitat modification.

Grass carp were actively stocked in private ponds in many states as early as the 1970s, and some have escaped. Grass carp have been detected in Lake Erie since the mid-1980s. Recent efforts to collect fish have resulted in low catch rates, indicating that fish are present in low densities. Although there is currently no evidence of negative ecological impact to the Lake Erie ecosystem attributed to grass carp, this ongoing study furthers research that could prove useful in providing methods to study other species, researchers said.

Categories: Blog Content, News, Ohio – Steve Pollick

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