Michigan Environment

Will grass carp spread in the Great Lakes?

Michigan Public | By Rebecca Williams

Published January 31, 2017 at 10:33 AM EST

There are grass carp in three of the Great Lakes, but it’s not too late to do something about it.

That’s one of the conclusions of a new risk assessment on this type of Asian carp by the United States and Canada.

Marc Gaden is the communications director for the Great Lakes Fishery Commission, one of the groups that did the study.

He says that grass carp have been in the Great Lakes for around 30 years, but they haven't posed much of a threat, because they were sterile, and not able to reproduce. Now, that’s changing.

“What’s particularly alarming is that over the last little while, probably the last five, six years or even a decade, biologists have been detecting more and more fertile grass carp in the lakes,” says Gaden. “And the presence of fertile grass carp in the lakes is an ominous sign of the fact that the invasion process of grass carp has begun and that the establishment of the population becomes more likely.”

Scientists have found that some grass carp are reproducing.

The risk assessment found it's likely that grass carp will become established (meaning: they're staying put and making babies) in lakes Michigan, Ontario, and Erie.

“And it’s Lake Erie where they also caught fertile grass carp through biological assessments," says Gaden. "The risk assessment notes that the likelihood of spread into Lake Huron is very likely within the next decade, and in fact, establishment in lakes Michigan, Huron, Erie, and Ontario is also very likely in the next decade.”

He says Lake Superior doesn’t have the right kind of habitat for grass carp, but it's within the habitat range for bighead and silver carp, if those kinds of Asian carp get into the lakes.

Gaden says grass carp have big appetites.

“They’re a huge risk to the Great Lakes because they eat aquatic vegetation in huge amounts, they root around in wetlands, they uproot the aquatic vegetation, and they generally destroy the wetlands or the embayments or the nearshore areas that they invade,” he says.

Crowdsourcing carp prevention

While officials work on tackling grass carp, there’s a new crowdsourcing challenge for the three other kinds of Asian carp that are considered threats to the Great Lakes: bighead, silver and black carp.

You might remember Governor Snyder announced an invasive carp challenge in his State of the State address.

Tammy Newcomb is with the Michigan Department of Natural Resources. She says they’re still working out the details. But she says they expect to offer $700,000 worth of prize money for innovative ideas on how to keep these carp out of the Lakes.

“Everything from an idea to something that could already be researched and developed. What’s exciting to me about this is that in these challenges you often get people in other areas who don’t think about fish like we do every day. And that is a creative space whereby they can look at the question and the problem differently,” she says.

She says they expect to open up the contest in July.