TVA proposing 10 barriers to limit spread of Asian carp

The Tennessee Valley Authority is proposing to build 10 barriers to help limit the spread of four invasive species of Asian carp at Chickamauga, Watts Bar, Nickajack, Kentucky, Pickwick, Wilson, Wheeler, Guntersville and Fort Loudoun dams, and the federal utility is seeking public input on ideas for controlling the fish.

A draft report was released by TVA this month to evaluate installation of deterrent systems at selected lock and dam sites along the Tennessee and Clinch rivers. The plan involves assessing the potential environmental and economic effects of Asian carp expansion and control, according to an agency news release issued July 7.

The U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service, Tennessee Wildlife Resources Agency, Alabama Division of Natural Resources, Kentucky Department of Fish and Wildlife and Mississippi Wildlife, Fisheries and Parks are serving as cooperating agencies on the draft document, according to TVA.

The draft is available for public review and comment through Aug. 5, and a public hearing on the proposal is being held online at 6 p.m. Thursday.

The carp problem is the target of $25 million in funding in the Water Resources Development Act of 2020, criticized by then-President Donald Trump as "wasteful" spending but cheered by the state's newly formed Carp Advisory Commission as its members studied Asian carp remedies. At the time, commission chairperson Rep. Mike Bell, R-Riceville, said Trump's criticism probably was "directed at the dysfunctional process in D.C. more than the specific funding of the fight against Asian carp."

Bell said the $25 million would help fund portions of the 10-barrier pilot program. According to Tennessee Wildlife Federation officials, the money would provide $4 million a year until 2025 and could reasonably fund three to five barriers that often use combinations of sound, light, bubbles and other technologies to block fish movement.

An acoustic barrier that uses sound to hold the fish at bay is being tested at the Barkley Dam, separating the Cumberland River Basin from the Ohio River.

TVA spokesman Scott Fiedler said the acoustic barrier at Barkley Dam is one example of barriers the federal agency is proposing.

Asian carp were first imported to the U.S. in the 1960s and 1970s as potential food fish and to improve water quality in fish farms. Soon after, the fish also were being used to control aquatic plants and algal blooms at municipal sewage ponds, according to TVA's mitigation proposal.

Purposeful stocking of connected water bodies, accidental releases and escapes allowed Asian carp to become established in the Mississippi River watershed by the 1980s, officials said, and since then the fish have dramatically expanded their range throughout the Mississippi River and into major tributaries, including the Tennessee River.

Asian carp are generally large-bodied fish - some weighing as much as 80 pounds or more - that prefer large, warm, turbid, slow-moving rivers but also inhabit reservoirs, lakes and ponds - habitats abundant in the Mississippi River watershed. Under preferred conditions, adult Asian carp can live for more than a decade, and a large female Asian carp can produce up to a million eggs a year, according to studies noted in the draft assessment.

Spawning requires lengths of uninterrupted river to keep the semi-buoyant eggs suspended in the flow until they hatch and become free swimming. Large reservoirs like those found on the Tennessee River system can be excellent habitat for Asian carp, according to officials.

There are four species of Asian carp - black, grass, silver and bighead. While all four are concerns to some degree, the silver and bighead species are most concerning in the Tennessee Valley, TWRA chief of fisheries Frank Fiss said during discussions of the problem in 2020.

Silver carp are the variety that leap from the water, and both the silver and bighead varieties are "filter feeders" that eat phytoplankton that other native species rely on for nourishment.

The fish reproduce readily and can't be controlled in West Tennessee, and there's a high abundance in Barkley Lake and Kentucky Lake and moderate abundance upstream in Pickwick Reservoir and Cheatham reservoirs, he said. There have been no reports in Cordell Hull Lake, where the lock is infrequently opened, and no small carp, indicating reproduction, have been found anywhere in the river since 2015.

But the adults are there, and danger of them finding a suitable habitat for reproduction remains.

In March 2017 an Asian carp was caught in Wheeler Reservoir, and there have been undocumented reports of bighead carp caught during a fishing tournament on Guntersville Lake in Alabama, according to Fiss's report. There also were reports in 2017 of what were likely bighead carp on Nickajack Lake. In October 2019, an image of a silver carp was reportedly taken on Chickamauga Lake but it remains unconfirmed.

Fiedler said TVA, while not the lead agency involved, is part of a national multiagency collaboration that is "crafting an effective plan and testing experimental methods that show good potential for controlling the spread of silver carp in the Tennessee River."

"TVA is committed to helping stop the spread of silver carp in the Tennessee River and to our role of supporting [Tennessee Gov. Bill Lee's] Asian Carp Commission, TWRA and other states and agencies in a joint effort to fight this invasive species threat," he said. "This includes studying the fish's reproduction, its movements in the system and evaluating the effectiveness of various barriers.

"Much work is being done, and we are seeing good results in our collaborative effort to address this issue," Fiedler said.

Contact Ben Benton at bbenton@timesfreepress.com or 423-757-6569. Follow him on Twitter @BenBenton.