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Species List Revisions:
Robert J. Noecker
January 5, 1998
The question of whether the Endangered Species Act (ESA) "works" is an important part of the debate before Congress concerning both its annual appropriations and reauthorization of the Act itself. Information on the species that have been delisted or downlisted from the Lists of Endangered and Threatened Wildlife and Plants is ofien cited when judging the ESA's success or failure. This report outlines the process and reasons for delisting or downlisting, and summarizes the 27 species delisted due to extinction, recovery, or data revision, and the 22 species that have been downlisted from endangered to threatened status due to stabilized or improving populations.
Central to the debate before Congress over appropriations for or reauthorization of the Endangered Species Act (ESA) is the question of whether the Act actually works. Different standards have been used to judge the ESA a failure and a success. Opponents of the Act contend that the ESA has failed while costing taxpayers billions of dollars, citing the low number of "recovered" species removed from the list. Proponents assert that the ESA has succeeded in preserving endangered and threatened species and their habitats, citing the significant number of listed species with stable or increasing populations, or the low number of extinctions of listed species.
Further controversy arises from uncertainty over the definitions of the terms "recovered" and "extinct." Should species that may have been already extinct when listed under the ESA be used to judge the Act's effectiveness? If a species has declined to a point that its very existence is in question, should a later determination that it is in fact extinct be attributed as a failure of the Act? Should species removed from the list because of the discovery of additional populations be classified as "recovered?" Should species downlisted from endangered to threatened due to stable or increasing populations count as "recovered?" Understanding the process and reasons for removing particular species from the endangered species list, or for reclassifying them from endangered to threatened, will help to answer these questions and to inform the debate.
To determine whether the ESA has been effective, one must first choose a standard of measure. The primary goal of the ESA is the recovery of species to levels where protection under the Act is no longer necessary. If this is the standard of measure, the Act could be considered a failure. As of July31, 1997, only 11 species have been delisted due to recovery. Of the remaining species that have been removed from the endangered and threatened lists, seven have gone extinct, and nine species have been delisted due to new or improved data.
Some scientific studies have shown that most species are listed only afier they are very depleted (e.g., median population of 999 animals for listed vertebrates, 1075 invertebrates, and 119.5 plants) 2, and recovery, in the short term, may be unrealistic.
Therefore, another standard of measure might be the number of species whose populations have stabilized or increased, even if the species is not actually delisted. Using this standard, the Act could be considered a moderate success, since a large number of the 1,676 listed species (41% according to one study) have improved or stabilized. Twenty-two species originally listed as endangered have been downlisted to threatened status, with two of these eventually being delisted altogether.
Another standard of measure for the ESA could be the number of species that have not gone extinct. While extinction can be considered a normal evolutionary process, widely diverse methods suggest that current rates of extinction exceed baseline rates by 100 - 10,000 times. With only 7 of the 1,676 listed species having gone extinct, (although 5 of these were later determined to have been extinct at the time of listing), tliis standard could be used to classify the ESA as a success. Species like the California condor and the red wolf might not exist today without ESA protection. On the other hand, less charismatic species at risk may have gone extinct without notice.
In sum, these three different standards would count the ESA as a failure, a modest success, or a success. Any participant in the ESA debate could therefore find support for his or her interests by choosing an appropriate standard of measure.
Congress first authorized the creation of a federal list of endangered species in the Endangered Species Preservation Act (ESPA) of 1966. As part of early efforts to halt or reverse the decline of wildlife species, this Act, in part, directed the Secretary of the Interior to publish the names of all species found to be "threatened with extinction" in the Federal Register (FR). The focus of this legislation was the protection of habitat, primarily through federal acquisition. It did not restrict taking or trade in interstate commerce of listed wildlife species.3
The Endangered Species Conservation Act (ESCA) of 1969 provided additional protections for declining species. A major innovation was the authorization to create a list of wildlife "threatened with worldwide extinction," and to strictly limit the importation of these species into the United States.4 The ESCA also directed the Secretary of the Interior and the Secretary of State to seek "a binding international convention on the conservation of endangered species."
The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the result of that congressional call, was signed by 21 nations in 1973 and took effect in 1975. One of its major contributions to endangered species protection was the recognition of different levels of endangerment.5 CITES listed species on one of three appendices: Appendix J listing the species most vulnerable to extinction; Appendix 11 listing species less vulnerable, or those species whose trade must be controlled to prevent endangerment; and Appendix ITI containing species that could be listed unilaterally by countries wishing to prevent over-exploitation of populations within their own boundaries.6 This agreement was significant both in substantively regulating international trade, and in providing a framework for domestic legislation.
Congress passed the Endangered Species Act in 1973, replacing both the ESPA and the ESCA. In addition to flirther restrictions on "taking" 7 and interstate commerce, the ESA authorized the listing of "endangered" 8 and "threatened" 9 wildlife and plants. Those species previously listed under the ESPA and the ESCA were directly incorporated into the Lists of Endangered and Threatened Wildlife and Plants under the ESA, found at 50 CFR §17.11(h) and §17.12(h).
The processes for delisting or dowrilisting a species from the Lists of Endangered and Threatened Wildlife and Plants are the same as the processes for listing (see Appendix). The Secretary of the Jnterior may initiate a change in the status of listed species. Alternatively, afier receiving a substantive petition for any change in listing status, the Secretary shall conduct a review of the species' status. The determination to delist, downlist, or uplist a species must be made "solely on the basis of the best scientific and commercial data available" (ESA, §4(b)(1)(A), "without reference to possible economic or other impacts." (50 CFR §424.11(b)) Fish and Wildlife Service (FWS) regulations also state that, at least once every five years, the Director shall conduct a review of each listed species to determine whether it should be removed from the list (delisted), changed from endangered to threatened (downlisted), or changed from threatened to endangered (uplisted) (50 CFR §424.21).
A species may be removed from the list only if the data substantiate that it is no longer threatened or endangered for one or more of the following reasons.
Atter a species has been removed from the endangered or threatened list due to recovery or an error in the original data, the FWS will continue to monitor its status to insure that proper action has been taken. Emergency re-listing may occur if these monitoring efforts show that the species is again endangered or likely to become endangered (50 CFR §424.20).
Of the 1,676 species on the Lists of Endangered and Threatened Wildlife and Plants (as of November 30, 1997), seven have been delisted due to extinction. Four of these species -- the Tecopa pupfish, longjaw cisco, blue pike, and Santa Barbara song sparrow -- were protected under laws pre-dating the ESA, and therefore were automatically listed under the ESA when it passed in 1973. They were apparently already extinct by 1973, however.
Tecopa pupfish. The Tecopa pupfish (Cyprinodon nevaensis) was first described in 1948 from the outflow streams of the north and south Tecopa Hot Springs, north of Tecopa, California. In 1970, the declining Tecopa pupfish population was listed on both the federal and California endangered species lists due to habitat alteration and introductions of exotic species, primarily bluegill sunfish and mosquito fish. By 1972, the species no longer occurred where the species was first found. Surveys done in 1977 failed to locate any other populations. In 1982, the FWS determined the Tecopa pupflsh was extinct and removed it from the endangered species list (47 FR 2317).
Longjaw cisco. The longjaw cisco (Coregonus alpenae) was one of several species of deepwater whitefish that was an important part of the smoked fish industry in the Great Lakes. It was known to occur in Lakes Michigan, Huron, and Erie. Extensive over-fishing and increased lake pollution led to a population crash in the first half of the 20th Century. The cisco was further decimated by sea lamprey predation and habitat degradation, and has not been seen in Lakes Huron and Erie since the 1950's. The last collection in Lake Michigan was in 1967, at which time the species was listed as endangered under the ESPA. In 1983, the FWS declared the longjaw cisco extinct and took it off the endangered species list (48 FR 39942).
Blue pike. The blue pike (Stizostedion vitreum glaucum) was abundant in the commercial fishery of the Great Lakes. It was historically found in Lakes Erie and Ontario, and in the Niagara River. ~ 1915, population levels began a cycle of extreme fluctuation caused by over-fishing, leading to the eventual collapse in 1958. The FWS listed the pike as endangered under the ESCA in 1970. suggesting that introgressive hybridization with walleye may have caused the final disappearance of the stock. A survey by the Blue Pike Recovery Team in 1977 found no individuals. In 1983, the EWS declared the blue pike extinct and removed it from the endangered species list (48 FR 39942).
Santa Barbara song sparrow. The Santa Barbara song sparrow (Melospiza melodia graminea) is a subspecies of the song sparrow that was known to exist only on Santa Barbara Island, Los Angeles County, California. No Santa Barbara song sparrows have been seen since a fire in 1959 destroyed most of the 640-acre island's habitat. In 1983, the FWS determined that M.m.graminea was extinct and removed it from the endangered species list (48 FR 46336).
Sampson's pearly mussel. Sampson's pearly mussel (Epioblasma (=Dysnomia) sampsoni) is a freshwater bivalve mollusk that was historically found in parts of the Wabash River in Illinois and Indiana, and parts of the Ohio River near Cincinnati. Dam construction and siltation eliminated much of the gravel and sandbar habitat where the species was found. The FWS listed this mussel as endangered under the ESA in 1976 (41 FR 24064). A status review initiated in 1981 determined that "no specimens had been collected in over 50 years, despite repeated sampling within its range." In 1984, the FWS concluded that Sampson's pearly mussel was extinct and removed it from the endangered species list (49 FR OS 7).
Amistad gambusia. The Amistad gambusia (Gambusia amistadensis) was a small fish known only to occur in Goodenough Spring, Val Verde County, Texas, a tributary of the Rio Grande River. This species was eliminated in the wild when construction of the Amistad Reservoir in 1968 submerged Goodenough Spring under approximately 70 feet of water. The FWS listed the Amistad gambusia as endangered in 1980, at which time it occurred only in captivity (45 FR 28721). The two captive populations, held by the University of Texas and the Dexter National Fish Hatchery in New Mexico, died or were eliminated through hybridization and predation. The FWS ruled the Amistad gambusia extinct in 1987, and removed it from the endangered species list (52 FR 46083).
Dusky seaside sparrow. The dusky seaside sparrow subspecies (Ammodramus maritimus nigrescens) was a small songbird that existed only on Merritt Island and the upper St. Johns River marshes of Brevard County, Florida. Populations of the sparrow declined as its salt marsh habitat was converted to freshwater mosquito-control impoundments, or drained. The use of DDT to control mosquitos was also suspected as a contributing factor in the species' decline.
Dusky seaside sparrows were first listed as endangered in 1967 under the ESPA (32 FR 4001). The last remaining wild birds, all males, were taken into captivity in 1979 and 1980 to begin a captive breeding program. The males were mated with females of a closely related subspecies (Scott's seaside sparrow, A. m. peninsulae) to try to preserve their genetic information. The hybrid offspring were not protected under the ESA and the breeding program proved unsuccessfiil. The last male sparrow died on June 16, 1987, and the hybrid offspring died by the summer of 1989. In 1990, the FWS declared the dusky seaside sparrow extinct and took it off the endangered species list (55 FR 51112).
2 Wilcove, David S., Margaret MeMillan, and Keith C. Winston. What Exactly is an Endangered Species? Analysis of the U.S. Endangered Species List: 1985-1991. Conservation Biology 7(1): 87-93. 1993.
3 Bean, Michael J. The Evolution of National Wildlife Law. New York, NY: Praeger Publishers, 1983. p.319-321.
4 Ibid., p. 321
5 Ibid., p. 325
6 While the ESA is the domestic legislation implementing many of the provisions of CITES, there is no necessary connection between species' listing on the Appendices of CITES and listing under the ESA.
7 Section 3(18) of the ESA defines the term "take" to mean "harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct."
8 Section 3(6) of the ESA defines the term "endangered species" to mean "any species which is in danger of extinction throughout all or a significant portion of its range other than a species of the Class Insecta determined by the Secretary to constitute a pest whose protection under the provisions of this Act would present an overwhelming and overriding risk to man."
9 Section 3(19) of the ESA defines the term "threatened species" to mean "any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range."
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