Closing The Door on Asian Carp in The Tennessee River


  • Native to China, silver, bighead, and black carp are invasive fish species imported to the US in the 1960s and 1970s as a potential food source and to improve water quality in fish farms and municipal water treatment facilities.
  • Primarily planktivores, silver and bighead carp pose serious threats to aquatic ecosystems and compete with native fish for resources and space, while silver carp present dangers to boaters as they leap from the water when disturbed.
  • Black carp feed primarily on mollusks, and there are significant concerns as to their potential impacts on sensitive native freshwater mussel populations.
  • Thus far, spawning populations of Asian carp have not established above the Kentucky Reservoir, and the TVA is proposing a series of innovative fish barriers to prevent the upstream advancement of Asian carp to protect the Tennessee River’s aquatic ecosystems, economies, and fishing and boating opportunities along the river and its many popular reservoirs.

Why it matters: Asian carp continue to expand their range in the Mississippi River Basin and its major tributaries. Large rivers with many large, mainstem impoundments like those on the Tennessee River represent ideal habitat for the establishment of spawning populations. While only the Kentucky Reservoir currently has a spawning population of silver carp, individuals of silver and bighead carp have been reported upstream of Pickwick Dam, the next dam above Kentucky Lake. The Tennessee Valley Authority recently release an Asian Carp Draft Programmatic Environmental Assessment that proposes to install a series of innovative fish barriers at strategic lock and dam locations along the length of the river. It is critical to both the economies and the aquatic resources of the Tennessee River Valley that the advancement of Asian carp is prevented from moving farther upstream.

In early July, the Tennessee Valley Authority (TVA) released an Asian Carp Draft Programmatic Environmental Assessment (Asian Carp PEA) that evaluated fish barrier options at 10 Lock and Dam (L&D) sites in the Tennessee River system and to consider potential environmental and economic impacts from their installation. Executive Order (EO) 13751, Safeguarding the Nation from the Impacts of Invasive Species (December 5, 2016), directed federal agencies to prevent the introduction, establishment, and spread of invasive species; and detect and respond rapidly to eradicate or control populations of invasive species in a manner that is cost effective and minimizes human, animal, plant, and environmental health risks. TVA’s Asian Carp PEA will comply with the EO by stopping the expansion of Asian carp further upstream into the Tennessee River system and allowing for more efficient localized control in the lower reaches.

On August 4, the Congressional Sportsmen’s Foundation (CSF) submitted a letter to the TVA expressing strong support for Alternative G in the Asian Carp Draft Programmatic Environmental Assessment (Draft EA), which proposes to install a combined system of Bio-Acoustic Fish Fences (BAFF’s) and diffused carbon dioxide barriers (CO2) at multiple strategic lock and dam sites within the Tennessee River system. BAFF’s are fish barriers consisting of sound signals, directional strobe lighting, and a bubble curtain, while CO2 barriers consists of a plume of CO2 diffused into specific areas within or around lock chambers as a chemosensory fish deterrent.

While other control alternatives were explored, only Alternative G was selected as the preferred path forward by a team of leading experts on Asian carp in North America, which consisted of state agency biologists and staff from the US Geological Service, US Army Corps of Engineers and the TVA.

The potential expansion of Asian carp into the upper reaches of the Tennessee River and its major tributaries represents a significant threat to the region’s economy, recreational fishing and boating opportunities, and native species biodiversity. Once established, invasive species are nearly impossible to eradicate, and management efforts must shift towards costly population control measures. Confining Asian carp to the downstream portions of the Tennessee River would allow for more focused population control where they currently exist and prevent the influx of new recruits from upstream reservoirs.

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