Tiny Tennessee fish protected, but US has yet to say where

NASHVILLE, Tennessee — It was a crisp fall day when biologist Bernie Kuhajda drove to a nondescript rivulet that flows through a Middle Tennessee cow pasture to try to save a small, colorful fish from extinction.

The rivulet—little more than a few large puddles of mud—was one of the last bodies of water with a population of Barrens Topelritze, and it was drying up.

So, pulling on waders and dragging a large screen through the muddy pools, Kuhajda and his team collected 64 of the small, iridescent killifish to bring back to the Tennessee Aquarium, where they maintain an “ark population” as a hedge against their possible disappearance from the aquarium wild.

“If we hadn’t saved those 64, that entire genetic population of Barren’s Topelritze would have disappeared,” Kuhajda said. “This species would have been one step closer to extinction, and now it’s not many steps away.”

That was in 2016, and while these fish have been rescued, the fate of the species is far from certain.

The Barrens Topelritze has spent more than 40 years in the limbo of endangered species – under constant scrutiny that has seen the fish’s chances of rescue suffered from the acrimony that came during a much publicized battle to save another tiny Southeast fish, the snailneck bird. The Topelritz was finally granted federal protection in 2019, but its future is still in doubt in part because the US Fish and Wildlife Service has not defined its critical habitat — the areas that need to be protected for it to recover.

Over the decades, its distribution has narrowed to a handful of springs and streams around Manchester, where the annual Bonnaroo music festival is held. During this period, it was both the victim of political backlash against the Endangered Species Act and the beneficiary of Herculean efforts to prevent its extinction.

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One of their proponents is biologist Pat Rakes, who researched Barren’s Topelritze for his master’s thesis at the University of Tennessee, Knoxville, and now co-directs the nonprofit Conservation Fisheries. This is one of several institutions that have maintained ark populations. Rakes said there are many good reasons to protect a small fish that many people might consider unimportant, and perhaps the best one is because all aquatic animals and plants work together to keep the ecosystem healthy.

As Rakes puts it, “You don’t throw away parts when you tinker with the machine, or you might not be able to put it back together.”

Barrens Topelritzen are about 10 centimeters long and live about three years. They eat beetles and small aquatic animals. Breeding males are brightly colored with reddish-orange markings on an iridescent blue-green body and bluish fins edged with yellow and black.

“You are absolutely gorgeous,” said Margaret Townsend. “They look like jewellery, like they’re set with precious stones.”

Townsend is an attorney with the Center for Biological Diversity, which recently threatened to sue the wildlife service for failing to designate critical habitats. The service has asked for patience, writing on September 7 that it is “working diligently” and expects to come up with a critical habitat proposal by the end of the year.

Barren’s top minnows are named for their habitat – Tennessee’s Barrens Plateau, so named because of the relative lack of trees. Small waterfalls and cascades isolate the waters of the plateau and keep downstream fish from encroaching on Topelritzen territory. But sometime in the 1960s or 1970s, the western mosquitofish was introduced in a misguided attempt to control mosquitoes – they eat mosquito larvae, but also Barren’s Topelritzen. Wherever the mosquitofish has been introduced, the Topelritz has disappeared.

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“They eat all the carp minnow eggs, all their larvae, and they harass the Barrens carbonaceous minnows — even though the Barrens carbonaceous minnows are larger — and pinch their fins,” Rakes said.

Recognizing the threats from habitat loss from agriculture and development, and from mosquitofish predation, the Fish and Wildlife Service first proposed listing the Barrens Topelritze as Vulnerable in 1977. That was shortly after the passage of the Endangered Species Act. It was also in the midst of the bitter snail battle that held up the Tennessee Valley Authority’s construction of a dam for over two years.

The battle against the snail spider blunted the public’s and politicians’ appetite for listing another small Tennessee fish as endangered. Listing faltered, and the Barrens topminnow made occasional appearances on the national register over the following decades while it was being reviewed.

In the 1990s and 2000s, the Fish and Wildlife Service signed conservation agreements with farmers like Raymond Cooper who wanted to protect topminhead habitat by fenced off cattle from the few sources where they still lived. Cooper said in a phone interview that even though the agreement had expired, he still had his cattle fenced in because it was the right thing to do “for the sake of the creek.”

“As far as I know Topelritzen are still hatching,” he said. “As long as I own the farm, it will be protected. But at 79, I won’t own them forever.”

Barren’s minnows might already have been extinct if biologists like Kuhajda hadn’t made efforts to collect them, breed them in captivity, and return them to the wild to restore viable populations.

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The fight to save the Topelritze bar is bigger than just a small fish, Kuhajda said. The American Southeast has the greatest aquatic biodiversity in the temperate world, with an amazing variety of fish, clams, aquatic snails, crayfish, and aquatic insects such as mayflies and dragonflies.

“It’s part of our natural heritage here in the Southeast and most people don’t know about it,” he said. “You won’t find most of these animals anywhere else but here. You can be proud of that.”

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