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A bright green irrodescent fish in a small blue net.
Information icon Barrens topminnow. Photo by Emily Granstaff, USFWS.

Proposed listing of the Barrens topminnow

What action is the U.S. Fish and Wildlife Service taking?

We are proposing to list the Barrens topminnow as an endangered species under the Endangered Species Act (ESA).

What does it mean when a species is listed as endangered?

A species is listed in one of two categories: endangered or threatened. An endangered species is one that is in danger of extinction throughout all or a significant portion of its range. A threatened species is one that is likely to become endangered in the foreseeable future throughout all or a significant portion of its range. The Service is proposing to designate the Barrens topminnow as endangered.

What prompted the Service to take this action?

The Barrens Topminnow was initially proposed to be listed in 1977 as endangered. Because of comments received on the proposed critical habitat and public opposition to listing, the critical habitat was re-proposed in 1979. However, the proposed listing rule was withdrawn in 1980 because it was not finalized within the required two years. The Barrens topminnow was designated a Category 2 Candidate species in 1982 and remained such until that list was discontinued in 1996. The fish was petitioned to be listed as part of the 2010 Petition to List 404 Aquatic, Riparian and Wetland Species from the Southeastern United States by the Center for Biological Diversity.

What conservation work has already been done for the topminnow?

Efforts to artificially propagate the Barrens topminnow began in the 1970s and have proved very successful at producing fish for stocking. In addition, the Service worked with landowners to protect and improve Barrens topminnow habitat through fencing-out livestock and increasing the amount of suitable habitat at certain sites by widening and deepening pools. Starting in the 1990s, a concerted effort was made to restock topminnows into 27 springs throughout their historical range with the cooperation of many landowners. One example illustrates the challenge conservationists face. The Service acquired a parcel of land with a spring on it that was added to the Tennessee National Wildlife Refuge (NWR). This spring had already been invaded by mosquitofish, so the spring was rehabilitated by poisoning out the mosquitofish, widening pools, installing a concrete low-water crossing to act as a barrier to future invasion by mosquitofish, and restocking the spring with barrens topminnow. Unfortunately, the barrier was overtopped in a flood and mosquitofish regained access to the spring resulting in the elimination of the topminnow from the spring in just a few years.

These conservation actions were coordinated by the Barrens topminnow working group, a partnership of USFWS Hatcheries and Ecological Services, Tennessee Wildlife Resources Agency (TWRA), Researchers from Tennessee Tech University, the Tennessee Aquarium, and Conservation Fisheries Inc. This partnership has worked to conserve the Barrens topminnow and monitor its populations, including rescuing fish from springs at risk of drying up during droughts.

What are the criteria for deciding whether to add a species to the endangered and threatened species list?

A species is added to the list when it is determined to be endangered or threatened because of the following factors listed in the ESA:

  • A: The present or threatened destruction, modification, or curtailment of its habitat or range;
  • B: Overutilization for commercial, recreational, scientific, or educational purposes;
  • C: Disease or predation;
  • D: The inadequacy of existing regulatory mechanisms; or,
  • E: Other natural or manmade factors affecting its survival.

How are those factors determined?

Before the Service can propose to list a species, biologists must first conduct a Species Status Assessment (SSA) report. The SSA is an in-depth review of the species’ biology and threats, an evaluation of its biological status, and an assessment of the resources and conditions needed to maintain long-term viability. The intent is for the SSA to be easily updated as new information becomes available and to support all functions of the Endangered Species Program from candidate assessment to listing to consultations to recovery. The SSA is a living document upon which other documents, such as listing rules, recovery plans, and five-year reviews, would be based if the species warrants listing under the ESA.

What threats were identified for the Barrens topminnow?

The predominant threat to the Barrens topminnow is predation and competition by the western mosquitofish (Factor C). The mosquitofish were apparently introduced into the area in an effort to control mosquito populations during the 1960s. The mosquitofish proved only moderately successful at controlling mosquitoes but were very efficient at outcompeting Barrens topminnows. Mosquitofish can expand their populations rapidly and move into all corners of an available water body. These traits helped them to move into most of the streams on the Barrens Plateau. Once mosquitofish move into an area where Barrens topminnows are present, topminnow reproduction essentially ceases, and the population is eliminated.

The introduction of mosquitofish resulted in a major reduction in the range of Barrens topminnows (Factor A), leaving them more susceptible to other threats. One of the other threats is drought (Factor E). Under normal circumstances, topminnows would move out of a drying stream, downstream into more permanent water, or if a population was eliminated, it could be reestablished naturally from other populations. With the introduction of mosquitofish, the populations of topminnows have become isolated, and therefore, the threat posed by a drought is greater.

What does the Barrens topminnow look like?

The Barrens topminnow is a small, colorful killifish that reaches up to four inches in length. Barrens topminnows have upturned mouths, flattened heads and backs, and rounded fins with dorsal and anal fins set far back on the body. Males are very showy during the spawning season, with bodies displaying bright, iridescent background colors of greens, blues and reddish orange spots, and their fins colored yellow. Females, juveniles and non-reproductive males are more drab with pale brown bodies sprinkled with darker spots on the sides.

Where does the Barrens topminnow live, and what unique characteristics does it require of its environment for survival?

Only on the Barrens Plateau in central Tennessee, in Cannon, Coffee, Dekalb, and Warren counties.

What do Barrens Topminnows eat?

Tiny crustaceans and aquatic insect larvae.

Where was the Barrens topminnow found before it was proposed as an endangered species?

It has always been found only in the Barrens Plateau.

How can I submit a comment?

We will accept comments received or postmarked on or before March 5, 2018. Comments submitted electronically using the Federal eRulemaking Portal must be received by 11:59 p.m. Eastern Time on the closing date. The Service must receive requests for public hearings in writing to the Tennessee Ecological Services Field Office, U.S. Fish and Wildlife Service, 446 Neal Street, Cookeville, TN, 38506, by February 20, 2018.

You may submit comments by one of the following methods:

  1. Electronically: Go to the Federal eRulemaking Portal: In the Search box, enter FWS–R4–ES–2017–0094, which is the docket number for this rulemaking. Then, in the Search panel on the left side of the screen, under the Document Type heading, click on the Proposed Rules link to locate this document. You may submit a comment by clicking on “Comment Now!”
  2. By hard copy: Submit by U.S. mail or hand-delivery to: Public Comments Processing, Attn: FWS–R4–ES–2017–0094, U.S. Fish and Wildlife Service, MS: BPHC, 5275 Leesburg Pike, Falls Church, VA 22041-3803.

We request that you send comments only by the methods described above. The Service will post all comments on This generally means the Service will post any personal information you provide us (see Public Comments, below, for more information).

How will my comments be used?

All relevant information received during the open comment period from the public, government agencies, the scientific community, industry or any other interested parties will be considered and addressed in the Service’s final listing determination for the Barrens topminnow.

Looking for more information?

Mary Jennings, U.S. Fish and Wildlife Service, Tennessee Ecological Services Field Office, 446 Neal Street, Cookeville, TN 38506; by telephone 931–528–6481; or by facsimile 931–528–7075. Persons who use a telecommunications device for the deaf (TDD) may call the Federal Information Relay Service (FIRS) at 800–877–8339.

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