Massive die-off of invasive fish in US river


Around half a million invasive Silver carp have died in a river in Kentucky - and it seems to be the only species affected.

The Kentucky Department of Fish and Wildlife Resources is investigating the die-off, which was discovered on April 23. The fish kill is estimated to have affected tens of thousands of the invasive silver carp over a 24-hour period and officials are saying is the largest kill of its kind recorded. Specimens have been taken to Kentucky State University for disease testing.

The Silver carp is one of four species of Asian carp that have spread throughout much of the Mississippi River basin after escaping from fish farms in the 1970s.

"Whenever there is one species of fish, you are definitely thinking viral or bacterial," said Paul Rister, western fisheries district biologist with Kentucky Fish and Wildlife. "It’s not anything water quality wise. If it was oxygen related or chemical related you would see other species. Primarily what we are seeing below Barkley Dam is all Asian carp."

In Kentucky, the fish are found throughout most of the Ohio River, Kentucky River, Green River, Salt River and Rough River. Kentucky and Barkley lakes also host large populations.

Silver carp — famous for their amazing leaping abilities — are a threat to native species because they feed on plankton, which forms the base of the food chain, which many sport fish rely upon after hatching. The alien fish crowd out native species and take over ecosystems. The species has been introduced to, or spread by connected waterways, into more than 80 countries around the world.

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