Barrens Topminnow Project
The Barrens topminnow (Fundulus julisia) is an extremely rare fish occurring in springs and spring influenced streams on the Barrens Plateau in south-central Tennessee. Dale Hollow National Fish Hatchery (NFH) is an active member of the Barrens Topminnow Working Group (Group), a conservation coalition dedicated to the protection of existing populations of Barrens topminnows (BTMs) while restoring and enhancing other areas within the species historic range for future reintroductions. The Group will focus on protection and management of the remaining wild populations of the Barrens topminnow, establishment of captive-bred populations, and reestablishment of the species within a significant portion of its historic range in Tennessee.
In support of this effort, BTMs propagated at Conservation Fisheries Incorporated (Knoxville, TN) and the Tennessee Aquarium (Chattanooga, TN) are being transferred to Dale Hollow NFH for grow-out and subsequent reintroduction into the wild. Juvenile fish are reared in closed, recirculation systems in order to control water temperature and prevent the spread of disease between various lots of BTMs and other aquatic species being reared at the hatchery. The typical BTM rearing system consists of a 300 gallon capacity circular tank (plastic or fiberglass), outfitted with a sponge filter (driven by compressed air) and two biofilters (trickling filters). Water is circulated from the tank, through the biofilters, and back into the tank with a magnetic drive pump. Fish are fed a mixed diet of frozen brine shrimp, frozen blood worms, and spirulina flakes. The bottom of the tank is covered with aquarium gravel, and green colored mop heads and plastic plants are provided for cover. The mop heads are made of green colored yarn and are intended to mimic the filamentous green algae which is typically a component of good BTM habitat. The grow-out period lasts from six months to one year. Dale Hollow National Fish Hatchery became involved in this program in Fiscal Year 2001.
Sixty-nine Barrens topminnows, grown-out at Dale Hollow NFH,were stocked at a site located on private land in Warren County, Tennessee in FY 2016. The reintroduction effort is closely linked to the Service’s Partners for Fish and Wildlife Program (Program). The Program works with private landowners to restore historic habitat types which benefit native fish and wildlife. Fish cannot be reintroduced if suitable habitat does not exist. Every lot of BTMs is screened for disease by the Warm Springs Fish Health Center, Warm Springs, Georgia, prior to transfer between facilities and prior to reintroduction into the wild.
Many of the locations where BTMs are currently found or have been found
historically, have large populations of Western mosquitofish (Gambusia affinis),
a factor which seems to preclude recruitment of young-of-the-year BTMs.
Competition with Gambusia is not the only threat that BTMs face. The Barrens
Plateau has experienced severe drought conditions in recent years. There have been
several instances where it became necessary to remove adults and juveniles for
holding after spring pools dried up. The rescued fish were held at the Tennessee
Aquarium and Conservation Fisheries Incorporated until conditions improved enough
to stock the fish back out. Dale Hollow NFH now maintains an empty 300-gallon
capacity, closed recirculation system in the event that we are asked to help
bring fish in from the wild for holding. We are currently holding 123 fish
(2015 Year Class) received from the Tennessee Aquarium. These are Elk River
Population fish that will be held at the hatchery as an ark population.