The Kentucky Department of Fish and Wildlife Resources is continuing to investigate a massive die-off of Asian carp discovered Wednesday, April 23, in the Cumberland River below Lake Barkley and a second smaller die-off in the Tennessee River below Kentucky Lake.
Initial Press Release on Fish Kill
The initial fish kill in the Cumberland River is estimated to have impacted hundreds of thousands of the invasive silver carp over a short period. The kill appeared to affect only silver carp leaving native species unaffected. On April 25th, district biologist Paul Rister and his crew were able to collect specimens and send them to fish health specialists at Kentucky State University as well as fish health biologists with the U.S. Geological Survey.
Second News Release on Asian Carp Fish Kill
A second smaller die-off occurred in the Tennessee River below Kentucky Lake and affected mostly silver carp although small numbers of bighead and grass carp were also affected. On Thursday, May 8, aquatic nuisance species biologist Paul Wilkes met specialists from the Warm Springs Fish Health Center, the U.S. Fish and Wildlife Service, and the Illinois Dept. of Natural Resources to investigate the fish kill below Kentucky Lake. Moribund fish were collected and necropsies were performed on-site to examine potential causes of the massive die-off.
Although the investigation is still underway, initial results indicate that a condition known as gas bubble disease may have played a role in the die-off. Gas bubble disease occurs when a fish is exposed to water supersaturated with gases like that which can occur below dams. The extra gas can form bubbles in the gill tissue reducing circulation- similar to a condition known as “the bends” in divers which occurs when they ascend too quickly from a deep dive.
In addition to damage due to gas supersaturation, abnormal hemorrhaging was noted in the brain cavity and other organs of sick fish.
Evidence of the fish kill has been documented to the confluence with the Ohio River. Kentucky Lake and Lake Barkley do not appear to be impacted at this time.
Testing for other pathogens will take several weeks to complete.
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Dead silver carp in Lake Barkley tailwaters. Photo by Paul Rister
Moribund silver carp sampled from below Kentucky Lake. Photo:Kevin Irons
Technicians from USFWS and KDFWR conducting necropsy on a silver carp. Photo: Paul Wilkes
A biologist from the Warm Springs Fish Health Center performs a necropsy on a silver carp. Photo: Kevin Irons
Tissue samples were taken to check for bacterial, viral, and fungal infections. Photo: Kevin Irons