"There Is, Technically, No Snail Darter," But the Snail Darter Still Delayed the Tellico Dam

A case study in how the Endangered Species Act encourages the politicization and distortion of science.

In the 1970s, the discovery of the Tennessee snail darter in the Tellico River was used to halt completion of the Tellico Dam under the Endangered Species Act (a tale many law students learn in TVA v. Hill). The dam was only completed after Congress expressly exempted it from the ESA's dictates.

It has long been understood that the snail darter was the right species at the right time, as it gave dam opponents a powerful legal weapon. Now, the New York Times reports, it turns out the snail darter was not really the right species, as it is not a distinct species at all.

"There is, technically, no snail darter," said Thomas Near, curator of ichthyology at the Yale Peabody Museum.

Dr. Near, also a professor who leads a fish biology lab at Yale, and his colleagues report in the journal Current Biology that the snail darter, Percina tanasi, is neither a distinct species nor a subspecies. Rather, it is an eastern population of Percina uranidea, known also as the stargazing darter, which is not considered endangered.

Dr. Near contends that early researchers "squinted their eyes a bit" when describing the fish, because it represented a way to fight the Tennessee Valley Authority's plan to build the Tellico Dam on the Little Tennessee River, about 20 miles southwest of Knoxville.

"I feel it was the first and probably the most famous example of what I would call the 'conservation species concept,' where people are going to decide a species should be distinct because it will have a downstream conservation implication," Dr. Near said.

What Dr. Near is hinting at is the incentive structure created by the ESA--an incentive structure that encourages the distortion and politicization of scientific findings.

Under the ESA, the listing of a species (or subspecies or distinct species population) triggers regulatory restrictions, such as those that halted the Tellico Dam. Section 7 of the Act, for example, bars federal agencies from undertaking actions that could jeopardize a species' survival or destroy any of its critical habitat.

As I explained in this paper, this means that if an interest group wants to influence regulatory decisions under the ESA, they need to influence the scientific findings that trigger regulatory constraints. What should be policy fights over whether the benefits of a project justify harms or risks to particular species instead become fights over whether something is a species or is at risk of extinction. Thus political and ideological concerns infect what should be scientific disputes over how best to identify what constitutes a distinct species.

From the article:

Dr. Plater, who also argued successfully for the fish in the Supreme Court case, took issue with the Yale study. He said the approach favored by Dr. Near and colleagues makes them genetic "lumpers" instead of "splitters," meaning they reduce species instead of making more. He believes the findings also lean too heavily on genetics.

"Whether he intends it or not, lumping is a great way to cut back on the Endangered Species Act," Dr. Plater said of Dr. Near.

Dr. Near said being described as a "lumper" was a pejorative in his world, and he added that most of the research he and colleagues had performed had resulted in speciation splits, including a 2022 study.

While the intent of the ESA is to provide greater protection of species, it is not clear the hard regulatory trigger actually maximizes the effectiveness of species conservation efforts. As I noted in this paper on the ESA's 50th anniversary, the Act has been far less successful at recovering species than one would like, and its unforgiving regulatory structure may be part of the reason.