Asian carp

Barkley Carp Barrier Has Positive Preliminary Results

Preliminary test results suggest a bio-acoustic fish fence (BAFF) installed at Barkley Dam in November 2019 is deterring the movement of Asian carp from the Cumberland River into Lake Barkley.

Lyon County (Ky.) Judge-Executive Wade White announced in June that a report he received from U.S. Fish and Wildlife Service (USFWS) Midwest Fisheries Center Director Teresa D. Lewis, Ph.D., indicated promising results.

Of the 254 silver carp tagged in the area during a study period from November 1, 2020, through February 13, 2021, 57 fish crossed the BAFF when it was turned off. Only four crossed it while the BAFF was on. Additionally, she said, the agency counted 3,181 times silver carp approached the BAFF when it was off but only 612 times when it was on, “suggesting possible avoidance behavior when the system is on.”

  “This news is promising and a critical first step in understanding the technology, but more time is needed to complete the study,” Lewis said in the report to White. “We still need to observe the effects on fish behavior over different seasons of the year and over longer periods of time to determine if they become acclimated to the deterrent. We will also be working with our partners to tag more silver carp to ensure we have a large sample size and statistically valid results.”

Until that work is done, she said, the preliminary results are in no way final or assured to hold through the remainder of the study.

“We anticipate the study will conclude in 2022, and we plan to share final results at that time,” Lewis wrote. “We are hopeful that this study will continue to show positive results for deterrent systems like the BAFF to help us achieve our goals in the continued fight against invasive carp.”

The BAFF evaluation project is a partnership among the USFWS, U.S. Geological Survey, the Nashville Engineer District, Fish Guidance Systems and the University of Minnesota.

During the evaluation period, the fence is switched off for a week and then on for a week, and tagged fish are monitored to see if they approach and cross the BAFF, which is installed on the river bottom, crossing the lock approach. Boaters using the lock or nearby Barkley Dam may at times notice a diagonal line of bubbles breaking the surface, a low-frequency, rhythmic noise or flashing white lights.  Because the BAFF is housed in concrete below the lock sill, it poses no danger for tows approaching it, according to the U.S. Fish and Wildlife Service.

BAFF testing was delayed last year after two lightning strikes rendered the system inoperative for a period of months, and developers were prevented from traveling from the United Kingdom to conduct repairs because of the global COVID-19 pandemic.

“I am very pleased to hear the success rate,” he said. “I’m disappointed it is taking so long to test, but that is just what it takes, I suppose.  The good news is I believe this is enough to present to Sen. [Mitch] McConnell for further funding. Sen. McConnell is working with the Corps of Engineers to move forward on more barriers to be placed at strategic dams to slow the movement of carp into new areas of water. There are many from the U.S. Fish and Wildlife Service, state Fish and Wildlife and MICRA who have put together a very good plan of where they would install barriers next. They are also working closely with our legislators on funding this plan.”

According to a barrier prioritization report from the U.S. Geological Survey (USGS), the next barriers are to be installed on the Tennessee River system. The system connects to the Cumberland River system through a canal between Lake Barkley and Kentucky Lake.

The USGS study used both a tradeoff analysis and a heuristic optimization analysis to model sequential barrier placement and targeted removal of Asian carp removal, incorporating uncertain effectiveness of the barrier.

“Our analyses are consistent with the intuitive notion that barriers installed downstream on the Tennessee River could arrest or slow carp movement upstream despite uncertainty about population dynamics,” the report says. “Both approaches to analyzing options identified installation of barriers at Kentucky and Pickwick dams would be optimal choices. Lessening the migration of new carp into the Tennessee River system and reducing biomass into the reservoirs at the leading edge of the invasion is expected to minimize the carp population throughout the system; however, our analysis indicates that the implementation of this strategy will depend critically on the assumed rate of upstream movement and barrier effectiveness.”

The optimal order of barrier placement would be at Kentucky, Pickwick and Wilson dams, according to the report. However, if a fourth barrier is within budget, the report says it should be installed at either Guntersville, Nickajack or Chickamauga dams.

“Further, the tradeoff analysis indicated that the BAFF system most frequently performed best on the multiple objectives, but the carbon dioxide barrier at Kentucky Dam and the acoustic barrier at upriver locations were optimal for some scenarios,” the report noted.

White said while the BAFF is an important deterrent, it is not the only method by which officials are seeking to remove the carp, which are known for jumping out of the water, injuring those at work and play on the river, damaging equipment and devastating native game fish species.

“Our best way to combat these fish immediately is commercial fishing,” White said. “In Kentucky we have a subsidy that helps keep our commercial fishermen in business and catching fish. My county has spent over $100,000 in subsidy money on top of the state subsidy to increase the carp fishing in our lake, and it has made a tremendous difference in a short time period. We have noticed a major difference in the carp population due to the hero commercial fishermen, and we must do everything possible to increase their subsidy and add a subsidy for our processors.  Without our commercial fishermen and our processors these fish would take over. Study of these fish is important, but we cannot study them out of the water. So I’m pushing hard for a large portion of the money from Congress to find its way to our commercial fishermen in the form of higher subsidies and a new subsidy for the processors.”