Does rarity constitute a threat under the Endangered Species Act?

Authors: Rollie White, Christopher Allen

Year: 2012 (xliv)

Abstract

Many endemic fishes in the American west are limited in numbers and distributions either by natural conditions inherent to their environment or directly or indirectly by human activities that have altered the ecosystems upon which these species depend. As a result of rarity, in combination with biological status and threats to their persistence, many species, subspecies or distinct population segments (hereafter species) have been afforded protection under the federal Endangered Species Act (ESA) of 1973 (Minckley and Deacon 1991). While most federal listings of fish in the American west were determined by an assessment of status and threats under the U.S. Fish and Wildlife Service’s (Service) listing policy, the role and contribution of rarity was clearly a factor in many decisions. The federal designations as threatened or endangered provided legal protections for these species and their unique habitats and led to implementation of many recovery actions aimed most often at protection of the species’ habitat through establishment of preserves or refuges. Despite decades of conservation gains since many of these fish were federally listed, none have been delisted under the ESA. One of the reasons most often supported for maintaining threatened or endangered status under the ESA despite many that have met downlisting or delisting recovery criteria, is the continued rarity of these species, even in the absence of threats. At a time when the Service’s budget is in decline, it is important to demonstrate success of the ESA by showing the ability to recovery species by downlisting and delisting as appropriate. One example is Borax Lake chub (Gila boraxobius) in southeast Oregon, a fish the Service recently recommended for downlisting from endangered to threatened in a five-year status review for the species. Because the species is found only in Borax Lake it will always be rare. However, without an operative threat, a rare species is in no greater danger of extinction than a more widespread species. In the case of Borax Lake chub, a number of recovery actions have been implemented that significantly reduce threats to the species such that a change in listing status was determined to be warranted. With Borax Lake chub as a case study, this presentation will explore the role of threats and species rarity in the Service’s listing and delisting process.