Glossary - Endangered Species Act

September 07, 2017

Here are some terms that you might encounter when reading about our work to protect, conserve, and recover species under the Endangered Species Act.

What does it mean for a species to be endangered or threatened under the ESA?

An endangered species is defined under the ESA as "any species which is in danger of extinction throughout all or a significant portion of its range."

A threatened species is defined under the ESA as "any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range."

Species designated as threatened or endangered are called “listed species”.

Learn more about how species are listed under the ESA. 

What are foreign species under the ESA?

Under the ESA, we must list species that are endangered or threatened regardless of where they are found.

For our tables of ESA-listed species, foreign species are defined as species occurring only in areas beyond the U.S. exclusive economic zone (EEZ) and territorial waters.

For recovery under the ESA, foreign species are defined as those listed species with current and historical geographical ranges exclusively within territorial seas or the EEZ of foreign nations.

Learn more about how we manage foreign species under the ESA.

What is a petitioned species?

Any member of the public may petition us to list a species as threatened or endangered, reclassify a species, or delist a species. We may also receive petitions to revise designated critical habitat for listed species. These petitions need the support of biological data. We consider any information submitted on the biology, distribution, or threats to the species, and data to support critical habitat revisions, when we evaluate the petition. Species undergoing this petition process  are called petitioned species.

Learn more about the petition process and how species are listed

>View currently petitioned species

What is a candidate species?

A candidate species is any species whose status we are currently reviewing to determine whether it warrants listing under the ESA.

Candidate species specifically refers to—

  • Species that are the subject of a petition to list and for which we have determined that listing may be warranted, pursuant to section 4(b)(3)(A); and

  • Species that are not the subject of a petition but for which we have announced the initiation of a status review in the Federal Register.

>View current candidate species

What is a proposed species?

A proposed species is one that is found to warrant listing as either threatened or endangered, or delisting, after completion of a status review and consideration of other protective conservation measures. We follow a strict legal process known as a rulemaking (or regulatory) procedure to propose to list or delist a species under the ESA. Public comment is always sought on a proposal to list or delist species under the ESA.

>View species proposed for listing

>View species proposed for delisting

What is a recovered species?

A species is recovered when it no longer requires Endangered Species Act protections and is delisted.

We have a recovery program with recovery plans to help species toward recovery.

What is a delisted species?

A delisted species is one that was  formerly listed as threatened or endangered under the Endangered Species Act, but has since been removed from the lists of endangered and threatened species.  We “delist” species for three reasons:

  • The species has recovered to the point that it no longer needs ESA protection.

  • The original information warranting listing has been shown to be incorrect, or new information suggests that the species is not actually endangered or threatened.

  • The species has become extinct.

>View delisted species under the ESA 

What is a distinct population segment?

Under the Endangered Species Act, a distinct population segment—or DPS—is a vertebrate population or group of populations that is discrete from other populations of the species and significant in relation to the entire species. NOAA Fisheries and the Fish and Wildlife Service released a joint policy defining the criteria for identifying a population as a DPS. The ESA provides for listing species, subspecies, or distinct population segments of vertebrate species.

What is an evolutionarily significant unit?

Under the Endangered Species Act, an evolutionarily significant unit—or ESU— is a Pacific salmon population or group of populations that is substantially reproductively isolated from other conspecific populations and that represents an important component of the evolutionary legacy of the species. The ESU policy (56 FR 58612) for Pacific salmon defines the criteria for identifying a Pacific salmon population as an ESU, which can be listed under the ESA.

What does take mean under the Endangered Species Act and what is incidental take?

Take as defined under the ESA means "to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct."

Incidental take is an unintentional, but not unexpected, taking.

When a species is listed as endangered, take prohibitions are automatically extended to it under ESA Section 9.

When a species is listed as threatened, NOAA Fisheries must issue protective regulations in order to extend any take prohibitions to the species under ESA Section 4(d).

What is designated critical habitat?

Critical habitat is defined as specific areas.

  • Within the geographical area occupied by the species at the time of ESA listing, if they contain physical or biological features essential to conservation, and those features may require special management considerations or protection; and 
  • Outside the geographical area occupied by the species if the agency determines that the area itself is essential for conservation.

Once designated, other federal agencies consult with NOAA Fisheries to ensure actions they fund, authorize, or undertake are not likely to adversely modify or destroy the critical habitat. Learn more about designated critical habitat

What is a 5-year review?

The Endangered Species Act requires periodic reviews of species that are listed as threatened or endangered to ensure that the listing is still accurate. These reviews are known as 5-year reviews

The 5-year review can be as straightforward as gathering current information on a species and determining whether recovery plan criteria have been met. Some species do not have recovery plans or have recovery criteria that do not meet all current ESA requirements. In these cases, the 5-year review will analyze information available on the species relative to the definitions of “endangered” and “threatened” and in the context of the five ESA section 4(a)(1) listing factors.

>View the most recent 5-year reviews

What is a status review?

A status review is the scientifically rigorous process we use to determine whether a species warrants protection under the Endangered Species Act. This scientific review involves collecting and analyzing the best available scientific and commercial information on the species, including its biology, ecology, abundance and population trends, and threats to the species, in order to evaluate the species’ current status and extinction risk.

View recent Status Reviews

What does anadromous mean?

Anadromous is the term that describes fish born in freshwater who spend most of their lives in saltwater and return to freshwater to spawn, such as salmon and some species of sturgeon. NOAA Fisheries has jurisdiction over most marine and anadromous fish listed under the Endangered Species Act.

What is the Code of Federal Regulations?

The Code of Federal Regulations (CFR) contains regulations created by various federal agencies to support and explain Federal statutes. Both the U.S. Fish and Wildlife Service and NOAA Fisheries have created wildlife and fisheries regulations to support and clarify sections of the Marine Mammal Protection Act and the Endangered Species Act. The wildlife and fisheries regulations pertaining to marine mammals and endangered species can be found in 50 CFR 1 – 599.

What is the Federal Register?

The Federal Register (FR) is the official daily journal of the United States Government and contains rules, proposed rules, and notices published by the various federal agencies. When we publish a final rule, proposed rule, or notice in the Federal Register, we refer to the document citation (for example: 81 FR  62259) which identifies the volume number (e.g, 81) and page number (e.g., 62259) on which the document begins.