The Kentucky Department of Fish and Wildlife Resources began investigating a massive fish die-off in the Cumberland River last week. Initially reporting tens of thousands of dead silver carp floating on the surface of the river, estimates have since ballooned to an estimated 500,000 Asian carp killed. Experts believe the recent die-off to be the largest involving Asian carp in the United States.
“Whenever there is one species of fish, you are definitely thinking viral or bacterial, ” said Kentucky Fish and Wildlife biologist Paul Rister. “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.”
Anglers first reported seeing dead fish as early as two weeks ago, although not in the large numbers that biologists have found last week. The cause of the die-off still stumps researchers, but biologists are hopeful that the incident can reveal a new weapon in the fight against Asian carp. Silver carp are among the four primary Asian carp species that have spread like wildfire in the Mississippi River since they arrived in the late 1960s. The large and highly adaptable species is out-competing native fish, which worries anglers and commercial fishermen. Silver carp also have a hand in destabilizing local food chains by consuming large amounts of plankton.
“It’s comforting to know there’s something out there that might take these things out before they just devastate everything,” said Fish and Wildlife Fisheries Director Ron Brooks. “Right now we just don’t have it.”
Fortunately, the mysterious die-off does not appear to be affecting any native fish. Samples have been collected from the scene and transported to Kentucky State University (KSU) for testing, with results expected in about a month. KSU researcher Bob Durborow has one theory on why so many fish died in such a short period.
“There is a brain pathogen that has been found in Asian carp in previous, smaller kills,” he told WKMS. “It is called Lactococcosis, possibly it could be that and that is what we’re going to be looking for in more fish we got [in] the labs.”
Kentucky is one of 31 states with Asian carp populations. The fish can be commonly found in the Ohio, Kentucky, and Green rivers.