First endangered Barrens Topminnows raised through aquarium collaboration returned to the wild

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Scientists with the Tennessee Aquarium have forged a new partnership with the Shedd Aquarium, The Maritime Aquarium, and the National Mississippi River Museum and Aquarium to save an endangered species. The Barrens Topminnow is a colorful fish that is only found in two locations in Middle Tennessee. By joining forces with other aquariums, the Tennessee Aquarium hopes the road to recovery is quicker for these aquatic animals.

Barrens Topminnow at the Tennessee Aquarium

An adult Barrens Topminnow at the Tennessee Aquarium. This colorful fish is an endangered species.

“Every species is important, whether it be a small fish like the Barrens Topminnow or something as large as an elephant. Losing even the smallest species can have a profound impact on an ecosystem." = Maritime Aquarium Aquarist Bert Sadler

Unless you’re a biologist, it might seem difficult to see what’s especially noteworthy about the endangered Barrens Topminnow.

Like many freshwater fishes, the Barrens undergoes a fairy godmother-like glow up during the breeding season, when it takes on an emerald, iridescent shimmer. Usually, though, it’s a drab yellowy-brown that helps it blend into the aquatic vegetation of the slow-moving streams it calls home.

Thanks to habitat degradation and competition with invasive Western Mosquitofish, the Barrens’ range has been severely reduced. Now, isolated populations live in just a half-dozen nondescript, spring-fed streams in the “barrens,” an equally nondescript region of rolling meadows in southeast middle Tennessee.

In short, it’s an easy fish not to see or care much about, a biological example of “out of sight, out of mind.”

And yet, despite its seeming mundanity, the Barrens Topminnow has become the focus of a collaborative partnership involving specialists at four aquariums located almost a thousand miles apart.

“You really can’t do any conservation work in isolation,” says Matt Hamilton, the curator of fishes at the Tennessee Aquarium, where work to save the Barrens Topminnow has been ongoing for more than 20 years. “These kinds of projects take partnerships and cooperative effort with multiple institutions and conservation groups coming together to work toward a common goal.”

On a crystalline late fall morning, Hamilton and aquarist Adam Johnson left Chattanooga and drove down a steep mountain highway to the banks of a spring-fed creek winding its trickling way through Middle Tennessee pastureland. Parked on the side of a rural two-lane highway, the pair donned waders and unloaded a cooler carrying 100 juvenile Barrens Topminnows.

Carefully carrying oxygenated bags filled with the young fish, the pair descended to the creek to let their charges acclimate to the brisk 54-degree water. Despite barely cresting the top of their boots, the stream was alive with darting schools of Barrens Topminnows, all of them either released by or the offspring of fish introduced to the site as part of the Aquarium’s long-term propagation effort.

The Barrens Topminnow drew national attention in October 2019 when it was federally listed under the Endangered Species Act. With this long-awaited announcement, additional federal resources and protections were made available to safeguard it. The fish in these bags, however, represent another important milestone in the long-running restoration effort.

The Barrens Topminnow project has been a focus at the Aquarium since 1998. However, in late 2018, Hamilton reached out to other accredited members of the Association of Zoos and Aquariums to see if anyone would be willing to lend their expertise to the project. The goal was to create an “ark,” a large enough and genetically diverse enough population in human care to bolster the overall numbers and ensure no single institution was solely responsible for this endangered fish’s survival.

Three other institutions signed up: Shedd Aquarium in Chicago, The Maritime Aquarium in Norwalk, Connecticut, and National Mississippi River Museum and Aquarium in Dubuque, Iowa.

About two-thirds of the bagged fish learning to love the chilly water of their soon-to-be home were offspring resulting from this new partnership. They arrived in Chattanooga earlier this year after being shipped hundreds of miles from The Maritime Aquarium and Shedd Aquarium. The National Mississippi River Museum and Aquarium’s propagation program is ongoing but has yet to produce offspring.

Despite being a species with no direct ties to the Windy City, to Illinois or to anywhere else in the Midwest, the decision to help save the Barrens Topminnow is perfectly aligned with Shedd Aquarium’s mission.

“This was a no-brainer,” says Keoki Burton, the Chicago institution’s supervisor of special exhibits. “Yes, these are animals that are technically not in our backyard, but they’re a lot closer to home than many of the other species we have here at Shedd Aquarium that we also care deeply about and want to educate people about.

“We want people to get in the mind-frame that we want to make sure we’re taking care of all animals, regardless of whether they’re found in our home state. That was an important part of why we wanted to join this effort.”

Conservation scientists tend to operate under the maxim that “an ounce of preservation is worth a pound of cure.” Or, more simply put, saving a species on the brink takes much more effort than protecting one that’s already doing well.

Fortunately, sharing the load makes the otherwise monumental task of staving off extinction somewhat more manageable, says Maritime Aquarium Aquarist Bert Sadler.

“By spreading the effort, we can do more to help species that need assistance,” Sadler says. “With more institutions helping, we can double or triple the effort and make that much more of an impact.

“Every species is important, whether it be a small fish like the Barrens Topminnow or something as large as an elephant. Losing even the smallest species can have a profound impact on an ecosystem. As such, we should do all we can to help any species that needs assistance.”

While the participation of multiple zoological institutions to save this fish may be a relatively recent development, the campaign to save the Barrens is rooted in a partnership that started in the late ’90s. Long-time collaborators in the Barrens Topminnow Working Group include Tennessee Wildlife Resources Agency, U.S. Fish and Wildlife, the Nature Conservancy and Knoxville, Tennessee-based Conservation Fisheries, Inc.

Since the group’s formation, more than 44,000 Barrens Topminnows have been reintroduced to suitable locations in the wild.

Back in Middle Tennessee, the newest additions to this tally have finally adjusted their new stream conditions. Carefully dipping the bags below the water’s surface, Hamilton and Johnson watch as the young fish enter into their ancestral waters for the first time. Many dart for cover in bankside vegetation or under the shadowy lee of rocks, looking — for all intents and purposes — as if they had been there all along.

After so many years spent working to save the Barrens, Hamilton says he welcomes any additional help in that effort. That that assistance is coming from those with no direct connection to Tennessee or its native species just makes it even more meaningful.

“For them to care and be willing to join in helping us to raise animals and send them back to us so we can release them as part of the recovery effort — that’s huge,” he says. “I’m just so thankful that they were willing to take the time and put forth the effort and resources to work with us to help be a part of this project.

“If you have healthy fish in the creeks where the water is coming out of the ground, that’s how you know you have a healthy river system. That benefits all of us, having clean water with thriving wildlife. That’s what we should all strive for.”

Learn more about the Barrens Topminnow.

Additional information about Shedd Aquarium’s effort to save the Barrens Topminnow can be found online.

Details of the Barrens Topminnow’s federal listing as an endangered species can be found online.

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Thom Benson
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