The Endangered Species Act (ESA) turns 37 this year. Since Congress enacted the ESA in 1973, 519 animals (including fish) and 746 plants have been listed as threatened or endangered. Of the total U.S. listed species, 1,016 species have approved recovery plans in place.
The start of the new year is a good time to look at how the ESA works.
Plant and animal species evolve and become extinct as part of the natural life process over very long periods of time. From fossil records, scientists have calculated the long-term rate of extinction for many species. The protection of endangered species initially arose from evidence that the extinction rate has significantly accelerated in the most recent period of earth’s history. The underlying concerns are that gene pools will lose important diversity necessary for adaptation and that we will lose the benefits these species may provide us (medicine, nutrient cycles, food).
The federal Endangered Species Act (ESA) protects species whose survival is recognized and listed as endangered or threatened.
The National Oceanic and Atmospheric Administration (NOAA) Fisheries Division (formerly NMFS) and the U.S. Fish and Wildlife Service (USFWS) share responsibility for implementing ESA requirements.
NOAA Fisheries has jurisdiction to implement ESA requirements for anadromous species - ones that migrate from the ocean to freshwater for spawning and rearing.
The U.S. Fish and Wildlife Service has the same jurisdiction with respect to freshwater species, plants and animals.
The authority granted under the Act includes listing decisions, designating critical habitat, developing recovery plans, and regulating “take” of a listed species. (A take means “to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct” [16 U.S.C. 1532(19)].)
The agencies take the best available scientific information to try to answer questions such as:
What was the historic population of the species?
What is the current population of the species?
Does the species inhabit the full range of its habitat?
What factors of decline does the species face within the range of its habitat?
Many factors contribute to survival or extinction of any particular species. A risk of extinction is calculated by looking at both the natural population status (numbers) and the present factors of decline such as habitat degradation, exotic species competition or water quality conditions.
Species are then given one of these status determinations:
Endangered status means the identified species is in danger of extinction throughout all or a significant portion of its range. An endangered listing automatically prohibits any action(s) that would result in a take of a listed species.
Threatened status means that the species is likely to become endangered in the foreseeable future. A threatened listing allows the development of a rule that may authorize certain activities to be exempt from the take prohibition.
Candidate status means that either the species does not face imminent extinction or additional information is necessary to determine whether it may qualify as threatened or endangered.
Proposed listings initiate a one-year timeframe for federal agencies to determine the risk of extinction and make a final listing decision. That decision will either be one of the above three categories or a "not warranted" decision which removes the species from ESA regulation.
The Endangered Species Act at Thirty: Vol. 1: Renewing the Conservation Promise
The Endangered Species Act at Thirty: Vol. 2: Conserving Biodiversity in Human-Dominated Landscapes