LEON — With its two spider-like electrodes dangling into the water, the big boat idled along slowly.
“There!” one of the men on the boat yelled, pointing toward a spot 20 yards away where a catfish skittered across the surface. A smaller boat zoomed toward the fish, and a man in the boat scooped the fish into a net.
This scenario got played out hundreds of times recently on West Virginia’s lower Kanawha River as biologists conducted research on the river’s flathead and blue catfish populations.
The big boat contained a generator that put an electrical charge into the water. The charge wasn’t enough to stun catfish, but it forced them to the surface where they could be netted.
“This method is different from what we use for other fish,” said Nate Taylor, a district fisheries biologist for the state Division of Natural Resources. “This specifically targets catfish. The low-frequency charge doesn’t seem to affect other species, like bass. It irritates the catfish, though, and they come to the surface to try to escape.”
The technique works on all three catfish species found in West Virginia waters — blue, channel and flathead. The research project focuses on blues and flatheads because those species are protected by special regulations.
“The blues and flatheads in this [part of the Kanawha] are really gaining a lot of popularity with anglers, especially now with people at home because of the COVID-19 outbreak,” said Vinnie Siegel, a West Virginia University graduate student spearheading the research. “We’re trying to get a handle on the [catfish] populations as they are right now.”
To ensure consistency from one part of the river to another, each pass of the shocking boat — called a “transect” — lasts 15 minutes.
“At each location, we run four transects in about 15 feet of water, roughly 30 feet from the shore,” Siegel explained. “After we capture the fish, we measure them, inject PIT tags into them, and tag them with a dart tag under their dorsal fins.”
The PIT (Passive Integrated Transponder) tags are tiny electronic devices, about twice the size of a grain of rice, that are placed under a fish’s skin with a large-bore hypodermic needle. The uniquely numbered tags allow biologists who recapture the fish to identify the original date and place of capture simply by hovering an electronic receiver over the fish’s back.
The dart tags are 3-inch-long plastic noodles, also uniquely numbered. Once attached to the fish, they allow anglers who might catch the fish to report the capture to the DNR.
“Anglers can clip the tag, take a picture of it, or just write the number down,” Taylor said. “We really encourage them to report these tags to us.
“They can call our district office in Parkersburg, or they can mail the tag into us. We give a small reward for anglers that do this. Right now, it’s a package of hooks.”
Taylor said the tags allow DNR biologists to collect more information about the fish’s movements throughout the river. “With recaptures, we might also be able to evaluate how many fish are in a pool,” he added.
Biologists have been studying catfish in the Ohio, Kanawha and Monongahela rivers for the past several years.
Taylor said the DNR has been able to get information about catfish movements on the Ohio by piggybacking off the U.S. Fish and Wildlife Service’s research into Asian carp.
“They have receivers located throughout the river,” he explained. “We were able to get permission to use their equipment so we could look at catfish movements.”
The receivers pick up signals from transmitters surgically implanted into the fish. By periodically downloading the data from the receivers, biologists can track how far a fish moves upstream or downstream from its original capture site.
“Not only have we been able to get movement data, we’ve also been able to determine population characteristics, as far as age and growth goes,” Taylor said.
Ultimately, data gathered during the surveys will help DNR biologists to determine the effectiveness of the state’s catfish regulations.
“Right now, we have special-regulation areas,” Taylor said. “Anglers are restricted to two blue cats a day, with a 24-inch minimum size limit. There’s a four-fish limit on flatheads, with only one fish of more than 35 inches allowed.”
He said anglers seem to be happy, particularly with the flathead regulations, which seem to be working well.
“The population appears stable, we have a lot of [reproduction], and there’s a really high density of large fish,” Taylor continued.
Fish populations evolve, however, and regulations that are effective and popular today might become less so as years go by.
“The purpose of this [research] is to evaluate those regulations,” Taylor said, “and see if maybe we can’t come up with something to better manage the fishery, and ensure it’s going to be there well into the future.”