A Tiny, 'Endangered' Fish Delayed a Dam's Construction in the 1970s. Now, Scientists Say the Snail Darter Isn't So Rare After All
A lawsuit to protect the snail darter from the Tellico Dam in Tennessee offered the first real test of the 1973 Endangered Species Act. But a new study disputes the fish's status as a distinct species
Though small, the snail darter has played an outsize role in American law, conservation and biology.
U.S. Fish and Wildlife Service Headquarters via Flickr
Senator Howard Baker of Tennessee described an “awful beast” in 1979. That beast—which he also called “the bane of my existence, the nemesis of my golden years, the bold perverter of the Endangered Species Act”—was none other than the snail darter, a fish no more than 3.5 inches in length. Still, the tiny creature had plagued the politics of Tennessee throughout the decade.
Since its discovery in the 1970s and protection under the Endangered Species Act, the snail darter has cast a long shadow over American law, conservation and biology. Against Baker’s wishes, a Supreme Court ruling about the endangered status of the little fish upended progress on a controversial dam in Tennessee for years.
But now, a new study published last week in Current Biology suggests the snail darter isn’t a genetically distinct species at all—and that it was therefore never endangered in the first place.
“There is, technically, no snail darter,” Thomas Near, an ichthyologist at Yale University and a senior author of the study, tells Jason Nark of the New York Times.
Instead, Near and his co-authors argue, the tiny fish known as Percina tanasi that embodied a David and Goliath battle against the Tellico Dam is an eastern population of the stargazing darter—not a distinct or endangered species.
The Tellico Dam in Tennessee, where the fish known as the snail darter held up construction for several years.
U.S. Fish and Wildlife Service Headquarters via Flickr
The controversy began in 1967, when the Tennessee Valley Authority initiated construction on a dam on the Little Tennessee River, some 20 miles southwest of Knoxville. Environmentalists, local farmers and the Cherokee, whose land and ancestral sites were to be flooded, opposed the project, per the New York Times. They sought a way to halt the dam, and, in 1973, a zoologist at the University of Tennessee named David Etnier found that solution.
Etnier was snorkeling with a group of students in Coytee Spring, not far from the dam site, when he discovered a previously unseen fish darting across the riverbed. He called it the snail darter, because of its feeding habits, and it received endangered species protection in 1975.
“Here’s a little fish that might save your farm,” Etnier reportedly told a local, according to The Snail Darter and the Dam by Zygmunt Plater.
Plater, an environmental lawyer, represented the snail darter in front of the Supreme Court after its endangered status went challenged by the TVA. He was initially victorious in protecting the fish: In 1978, the Supreme Court ruled that “the Endangered Species Act prohibits impoundment of the Little Tennessee River by the Tellico Dam” because of the presence of the endangered snail darters.
The ruling in Tennessee Valley Authority v. Hill “gave teeth” to the new Endangered Species Act and “helped to shape environmental law for decades to come,” according to a statement from Yale.
But lawmakers like Baker were still eager to see the dam completed and derided the decision as environmental overreach, seeing little reason to delay a major project for a seemingly minor fish. Representative John Duncan Sr., a fellow Tennessee Republican, called the snail darter a “worthless, unsightly, minute, inedible minnow,” according to the New York Times.
The anti-fish brigade ultimately triumphed in 1979, however, by adding a rider that exempted the Tellico Dam from the Endangered Species Act to a spending bill. Jimmy Carter signed the whole bill into law, and the dam opened just a few months later.
In the meantime, conservationists “scrambled to save the small fish by moving it to other waterways,” as David Kindy wrote for Smithsonian magazine in 2021. Their efforts resulted in a resurgence of the snail darter population that led to its removal from the endangered species list in 2022.
U.S. Interior Secretary Deb Haaland called its recovery “a remarkable conservation milestone that tells a story about how controversy and polarization can evolve into cooperation and a big conservation success,” according to the Associated Press.
But Near’s new study casts this entire history into doubt.
A historical range map for the snail darter (Percina tanasi) in the Tennessee River watershed is shown in red, and the stargazing darter's (Percina uranidea) historical range is shown in blue.
Ghezelayagh et al., Current Biology, 2024. Photographs courtesy of Uland Thomas and Jon Michael Mollish
Jeffrey Simmons, a co-author of the study and former biologist with the TVA, was wading through the creeks near the Mississippi-Alabama border in 2015, when he thought he saw a snail darter far from where it was known to dwell. This apparent discovery prompted a team of scientists led by Ava Ghezelayagh, then an ecologist at Yale, to undertake anatomical and genetic research of the fish.
“Our approach combines analyses of the physical characteristics and the genetics, which scientists weren’t doing in the 1970s,” Near says in the statement.
“Despite its legacy, the snail darter is not a distinct species,” the authors of the study conclude.
But the disputed fish has not left its controversy behind quite yet.
Plater, the lawyer who defended the fish in court, takes issue with the study, calling the researchers “lumpers” instead of “splitters,” according to the New York Times. That means they tend toward reducing species with their research rather than expanding them.
“Whether he intends it or not, lumping is a great way to cut back on the Endangered Species Act,” Plater says of Near to the New York Times.
Near, for his part, argues that, “while we’re losing the snail darter as a biological conservation icon, our findings demonstrate the capability of genomics, in addition to studying an organism’s observable features, to accurately delimit species,” he says in the statement. And, in other genetic and anatomical research, his teams have uncovered new species.
“We’re discovering species that are truly imperiled, which helps us better understand where to devote resources to protect biodiversity,” he adds.
“This is still a success story,” Simmons says to the New York Times. “Its listing under the Endangered Species Act worked, regardless of what you call this fish.”
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