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Designating Experimental Populations Under the Endangered Species Act


Section 10(j) of the ESA allows NOAA Fisheries to designate populations of listed species as “experimental” to support the reintroduction of at-risk species to foster long-term recovery.
Endangered Species Act
Action Status
Final Rule


NOAA Fisheries issues final regulations to amend the Code of Federal Regulations (CFR) to implement the Endangered Species Act (ESA) regarding experimental populations. This rule amends the CFR to establish definitions and procedures for:

  • Establishing and/or designating certain populations of species otherwise listed as endangered or threatened as experimental populations
  • Determining whether experimental populations are “essential” or “nonessential” 
  • Promulgating appropriate protective measures for experimental populations

Section 10(j)(1) of the ESA defines an experimental population as a population that has been authorized for release by the Secretary of Commerce or Secretary of the Interior, but only when, and at such times as, the population is wholly separate geographically from nonexperimental populations of the same species. The Secretary may authorize the release (and related transportation) of any experimental population (including eggs, propagules, or individuals) of a listed species outside of the species' current range if the Secretary determines that the release would “further the conservation of” the listed species. Section 10(j)(2)(B) also requires that, before authorizing the release of an experimental population, the Secretary “identify” the experimental population by regulation and determine, based on the best available information, whether the experimental population is “essential to the continued existence” of the listed species.

Federal Register

Last updated by Office of Protected Resources on 06/10/2020