Experimental population are members of a listed species that are geographically separated from other populations of the same species pursuant to rule published in the federal register, and are designated as ‘experimental population.’ The offspring of such experimental population are also isolated geographically from non experimental members of the same species. An experimental population may be subject to relaxed restrictions as compared to the rest of the species to which it belongs. The experimental population designation relaxed existing ESA regulations by allowing reintroduced species to be managed or controlled. For example, ranchers were allowed to kill reintroduced wolves that threatened livestock.
The following is an example of a fedral statute defining the term 'experimental population.'
16 USCS § 1539(j). Experimental populations.(1) For purposes of this subsection, the term "experimental population" means any population (including any offspring arising solely therefrom) authorized by the Secretary for release under paragraph (2), but only when, and at such times as, the population is wholly separate geographically from nonexperimental populations of the same species. (2) (A) The Secretary may authorize the release (and the related transportation) of any population (including eggs, propagules, or individuals) of an endangered species or a threatened species outside the current range of such species if the Secretary determines that such release will further the conservation of such species. (B) Before authorizing the release of any population under subparagraph (A), the Secretary shall by regulation identify the population and determine, on the basis of the best available information, whether or not such population is essential to the continued existence of an endangered species or a threatened species. (C) For the purposes of this Act, each member of an experimental population shall be treated as a threatened species; except that-- (i) solely for purposes of section 7 (other than subsection (a)(1) thereof) [16 USCS § 1536], an experimental population determined under subparagraph (B) to be not essential to the continued existence of a species shall be treated, except when it occurs in an area within the National Wildlife Refuge System or the National Park System, as a species proposed to be listed under section 4 [16 USCS § 1533]; and (ii) critical habitat shall not be designated under this Act for any experimental population determined under subparagraph (B) to be not essential to the continued existence of a species. (3) The Secretary, with respect to populations of endangered species or threatened species that the Secretary authorized, before the date of the enactment of this subsection [enacted Oct. 13, 1982], for release in geographical areas separate from the other populations of such species, shall determine by regulation which of such populations are an experimental population for the purposes of this subsection and whether or not each is essential to the continued existence of an endangered species or a threatened species.