Scientists using electro-shock to get catfish species under control

South Carolina wildlife biologists are looking to control a fish species that may be taking over many state rivers.

They were on the Little Pee Dee River Wednesday conducting a study on the flathead catfish.

The flathead is an invasive species to the state and as its population grows, the large predator pushes out other prized game species, like the redbreast sunfish and the shellcracker.

"They eat a lot of fish and they can really do some damage to a fishery," said Department of Natural Resources fisheries biologist Carl Bussells.

DNR biologists are pulling 500 flatheads or more each day out of the Little Pee Dee by using an electro-shock technique.

A generator on board a boat drives an electrical current through wire probes in the water.

The electrical shock stuns the catfish and other water life, but doesn't kill them. It causes the fish to pop to the surface and the flathead catfish are then netted by biologists in another boat.

The catfish are then weighed and measured, and their ear bones are removed during a necropsy.

"And we use those ear bones to actually get an age on them. You count the rings on them, like you would on a tree," Bussells said. "We can also look at the stomach contents and kind of figure out what their preferences are for the river system."

When the biologists are done with their measurements, the catfish are not given to food banks or charities for human consumption. The concern is mercury contamination of the fish.

"Flatheads, because they're such an apex predator, because they're the top of the food chain, they really accumulate a lot of mercury," Brussells said.

At the same time, Bussells said the catfish are prized by sport fishermen, and the DNR encourages anglers to go after the flathead.

"Basically, the species isn't native to the area, so the more we can get them out of the river system, the better," said Bussells.

What biologists are doing at the river this week is just a study, Bussells said, but it could lead to using the same electro-shocking on a wider scale to keep the flathead population in check.