As the result of new scientific classification information, the U.S. Fish and Wildlife Service is withdrawing its proposal to list two minnows, the headwater chub and a distinct population segment of the roundtail chub in the Lower Colorado River Basin, as threatened species under the Endangered Species Act.
In proposing to list the two chubs in October 2015, the Service relied upon a comprehensive species status assessment. At that time, the American Fisheries Society and the American Society of Ichthyologists and Herpetologists Joint Committee on the Names of Fishes – the recognized authority on fish taxonomy – considered the headwater chub and roundtail chub (and the currently listed Gila chub) to be separate species.
Representative Paul Gosar, who spearheaded an effort that raised serious concerns about the process, asked the Service to withdraw the proposed rule to list the headwater chub and a district population segment of the roundtail chub as threatened species. A letter from Gosar to the U.S. Fish and Wildlife Service was cosigned by Trent Franks and David Schweikert.
“I am hopeful that the announcement by the Service to withdraw the proposed listing of the headwater chub and roundtail chub signals a new dawn where commonsense and science drives decision-making within the agency,” stated Gosar. “For too long, unwarranted species listings—not supported by verifiable evidence—have been detrimental not only to local stakeholders, but also to the species themselves. I’m proud to have teamed up with the Arizona Game and Fish Department and several of my colleagues in the House to help prevent these misguided listing proposals that would have had significant consequences for Arizona and New Mexico.”
In September 2016, the Joint Committee found the three fishes are actually a single species – the roundtail chub (Gila robusta). Because the entities previously proposed for listing are no longer recognized as species, we have determined that they are not listable entities and are withdrawing our proposed rule.
“Endangered Species Act determinations are founded on the best available science. When new science becomes available, especially midstream in a listing processes, we evaluate it and respond accordingly,” said Steve Spangle, the Service’s Arizona Field Supervisor. “Our withdrawal of the listing proposal for the former headwater chub and roundtail chub DPS reflects this new science indicating that these are no longer valid species.”
“For the purposes of our determination, we accept the ‘single species’ finding by the Societies described above and, consequently, withdraw the proposed rule to list the headwater chub (Gila nigra) and a [distinct population segment] of the roundtail chub (Gila robusta) from the lower Colorado River basin as threatened species under the Act,” the Service wrote in the notice.
American Fisheries Society and the American Society of Ichthyologists and Herpetologists Joint Committee on the Names of Fishes’ determination resolved a long-running debate that vexed fishery biologists in the field for decades – not being able to discern the identity of these chubs without considering the watershed where they were collected.