Invasive Asian carp are breeding in the Great Lakes basin

A team of scientists in the United States have found the first evidence that a particular species of Asian carp has been breeding in Ohio's Sandusky River, which is bad news for those charged with controlling the spread of these invasive fish.

Grass carp are native to China, and were introduced to the United States back in the late '60s, as a way to control aquatic weeds. Efforts were taken to keep them out of the local watersheds, though, since these carp, and others like them, are 'big eaters'. They can consume all the plants that other fish use to spawn in and eat all the plankton and other smaller organisms in the water, thus starving out native species. This can devastate the local ecosystem.

Some of these carp have escaped over the years, and agencies on both sides of the border keep a careful watch out for them. One thing that limited the carp, though, was that there were only so many rivers around the Great Lakes that were long enough and had the right flow for the carp to successfully breed in. With the researchers finding that these grass carp are breeding in the Sandusky River, which was thought to be too short for their needs, all of that has changed.

Grass carp themselves are one concern, but the real worry now is that many of these invasive carp species need the same kind of conditions to spawn. If the grass carp can successfully breed in a smaller river like the Sandusky, it's possible that other species could as well, and that opens up a lot more waterways around the Great Lakes that need to be monitored.

"It's bad news," said Duane Chapman, a fisheries biologist with the US Geological Survey that was on the research team, according to CBC News. "It would have been a lot easier to control these fish if they'd been limited in the number of places where they could spawn. This makes our job harder. It doesn't make it impossible, but it makes it harder."

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The research team is now putting together a new list of the rivers that could be suitable for these carp to breed in, and the US Army Corp of Engineers is apparently working on a report that will detail long-term solutions to the problem. Currently, one way of keeping the invasive carp that already dominate the Mississippi River ecosystem out of the Great Lakes is by using electric barriers, like the ones at the bottom of the Chicago Sanitary and Ship Canal.

(Photo courtesy: Ontario Ministry of Natural Resources)

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