Grass carp threat grows

The threat of Asian carp has been highlighted by the media, but a new carp variety, the grass carp, is also threatening the Great Lakes.
Alex Doty
Apr 9, 2014

“They’re one of the carps that that don’t get the most attention,” Michigan Sea Grant educator Dan O’Keefe said.

According to the Michigan Department of Natural Resources, grass carp can grow up to 5 feet long and weigh more than 80 pounds. They have large scales that appear crosshatched and eyes that sit even with the mouth.

“They do look different than the common carp,” O’Keefe said. “Most people who catch them are bow fishing.”

Given the fish’s appetite for plants that make up local waterways, it is a concern.

“They eat rooted plants that some would call weeds,” O’Keefe said. “They eat the plants that young fish tend to hide in.”

This, O’Keefe noted, could cause problems for the development of other fish that use these areas to spawn. The elimination of the habitat is also bad for waterfowl that rely on the areas, he said.

“The grass carp eat a huge amount of biomass,” O’Keefe said. “They can’t digest plants very well (and can) cause blooms of plankton.”

While there haven’t been any sightings of the invasive fish in the Tri-Cities area’s water, that’s not to say it couldn’t happen.

“They could show up in local rivers,” O’Keefe said. “This is a place to expect to find them, if they are around.”

Knowledge about the fish is also changing, especially in discussing its fertility.

In an article published by the Canadian Journal of Fisheries and Aquatic Sciences, researchers said 45 grass carp are known to have been caught in the Great Lakes basin from 2007-12. Some were found in Lake Erie and others in tributaries of the lakes.

“For the first time, there is evidence that they are reproducing in the Great Lakes basin, in the Sandusky River in Ohio,” O’Keefe said.

About half of those caught could reproduce, which could mean the lakes already have a breeding population, the report says.

To read the whole story, see today’s print or e-edition of the Grand Haven Tribune.

The Associated Press contributed to this report.



They good for food or for fertilizer

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