Grass carp spawning in Lake Erie watershed

by Megan McPhaden | June 10, 2016

Grass Carp

A student from the University of Toledo has found evidence that proves grass carp, a species of Asian carps, are spawning in a Great Lakes tributary. The discovery represents the first time that grass carp have been found naturally reproducing in the Great Lakes basin.

In the summer 2015, Holly Embke, a graduate student at the University of Toledo, collected eight eggs from the Sandusky River in Ohio – a tributary that flows into Lake Erie. DNA testing later confirmed the eggs belonged to the invasive grass carp.

“Our native fish and plant species will be at risk if grass carp become established in the Great Lakes Basin,” said Brook Schryer, the Aquatic Invasive Species Outreach Liaison with the Invading Species Awareness Program.

Grass Carp in Canada

According to the Department of Fisheries and Oceans, grass carp were first discovered in Canada back in 1985 after they were caught in Lake Erie.

Embke says they were thought to be sterile specimens used for aquatic weed control.

In an Asian Carp Risk Assessment Report from 2004, the report classified grass carp as having a high probability of successfully colonizing and maintaining a population if introduced. In late May a grass carp was caught in the St. Lawrence River.

In a release from the U.S. Geological Survey, Rich Carter, Executive Administrator for fish management and research with the Ohio Department of Natural Resources, said while the discovery of the eggs is ‘disconcerting’ populations of grass carp in Lake Erie are very low. According to Carter there is no evidence of negative impacts to the Lake Erie ecosystem that can be attributed to grass carp.

Potential Impacts of Grass Carp on Ecosystems

When it comes to their diet, grass carp are herbivores with an insatiable appetite for vegetation.“The grass carp is quite different from its other Asian carp relatives,” said Brook Schryer.”Unlike the silver and bighead that feed on plankton or the black carp that feeds on snails, the grass carp lives up to its name and feeds on submerged aquatic plants.”

This doesn’t bode well for native fish populations or waterfowl habitats and wetlands. Schryer says their appetite is what poses a risk, “Grass carp can alter habitats for native fish communities that reside near the shoreline where the grass carp is most likely to feed.”

Embke presented her findings at the annual International Association for Great Lakes Research conference at the University of Guelph on June 9.

For more news on Asian carps and how to identify them click here.

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