Asian Carps Breeding in Great Lakes, USGS Study

A  U.S. Geological Survey study has found that four species of grass carp, a species of Asian carp, have reproduced in the Great Lakes watershed. The presence of these invasive fish in lakes could threaten native fish population.

Grass carp were brought in Arkansas during the 1960s to control aquatic plants. However, pretty soon they became a threat to the local ecosystem due to their large size and appetite. A new U.S. Geological Survey study has shown that Asian carps are breeding within the Great Lake watershed, a bad sign for local fisheries.

The fish species were captured last October from the Sandusky River in Ohio. Researchers found that the fish had spent their entire lives in the lakes and weren't introduced by nearby fish farms.

For the study, researchers looked at the bones in the fishes' head. These bones, also called otoliths, hold clues about the fish's life history.

Asian carps are native to Eastern Russia and China and include bighead carp (Aristhythys nobilis), silver carp (Hypothalmichthys molitrix), black carp (Mylopharyngodon piceus), and grass carp (Ctenopharyngodon idella). Of these, Bighead and Silver carp pose a huge problem for local U.S. fisheries as they compete with the native fish. These fish are also considered a public hazard as they are highly excitable and usually leap out of water, injuring boaters.

The latest USGS study provides evidence that Asian carps could breed in these waters. Experts say that the presence of these fish could threaten the $7 billion fishing industry of the region.

"These findings are significant because they confirm recent USGS research indicating that shorter rivers, like the Sandusky, are potential spawning sites for grass carp and other Asian carps as well," said USGS scientist Duane Chapman in anews release. "The study may also provide resource managers an opportunity to address the spread of grass carp before it becomes problematic."

The study is published in the Journal of Great Lakes Research.                                            

The presence of grass and Asian carp in Great Lakes is shocking, but not entirely unexpected. Previous study by Waterloo University, Canada, researchers and colleagues had warned that few Asian carps are enough to wipe-out native fish in the Great Lakes. In April, another team of researchers had reported finding Asian carps in these lakes.