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Introduction ll species of sea turtles that live in U.S. waters are listed as endan- ~ gored or threatened under the Endangered Species Act of 1973 |. (ESA). An endangered species is one that is in danger of extinction ~ throughout all or a significant portion of its range; a threatened · · species is one that is likely to become endangered throughout all or a significant portion of its range within the foreseeable future. The ESA requires protection of both categories. A principal goal of this report, which was mandated by the 1988 amendments to the ESA, is to provide a sound scientific basis for protecting these endangered and threatened species of sea turtles. The le atherback (Derm och elys co Ma cell) and hawksbill (Eretm ochelys imbr~cata) were listed as endangered throughout their ranges on June 2, 1970. The Kemp's ridley (Lepidochelys kempi) was listed as endangered on December 2, 1970. The green turtle (Chelonia mydas) was listed on July 28, 1978, as threatened, except for the breeding populations of Flori- da and the Pacific coast of Mexico, which were listed as endangered. On July 28, 1978, the loggerhead (Caretta caretta) was listed as threatened throughout its range. Those sea turtles were listed because, to different degrees, their popu- lations had declined largely as a result of human activities. They have been prized worldwide as meat for human consumption, their eggs con 16
17 Introduction sumed or used as aphrodisiacs, their oil used for lubricants and ingredi- ents in cosmetics, and their shells used for jewelry and eyeglass frames. Mass slaughter of turtles and plunder of their nests have been and remain a prime cause of population declines. Many nesting beaches were severe- ly degraded by encroachment of human populations into coastal habitats. Sea turtle populations have been reduced by uncontrolled harvesting for personal or commercial purposes and by mortality incidental to such activities as commercial fishing. For at least 2 decades, however, several factors appear to have con- tributed unevenly but increasingly to the decline of sea turtle populations along the Atlantic coast and in the Gulf of Mexico: physical and ecologi- cal degradation of turtle nesting habitats; plastics and persistent debris in marine ecosystems; continued turtle harvesting in international waters; activities associated with oil and gas development; collision with power boats; explosive devices; and shrimp trawling. In fact, several reports in the 1980s argued that the inadvertent capture and mortality (presumably through drowning) of sea turtles in shrimp trawls were major factors hin- dering the recovery of the species. The ESA prohibits capture of endangered sea turtles within the United States and its territorial waters and on the high seas, except as authorized by the Secretary of Commerce or the Secretary of the Interior. The Secre- tary of Commerce has authority over sea turtles in marine waters and the Secretary of the Interior has authority over sea turtles on land. ESA authorizes the secretaries to extend to threatened species the same pro- tections provided to endangered species. Under the ESA, it is unlawful to import, export, take, possess, sell, or transport endangered species with- out a permit, unless these activities are specifically allowed by regulation. Early observations of sea turtle populations strongly indicated that inadvertent capture and death of sea turtles in shrimp trawls was a major mortality factor of the species. To prevent further declines in the popula- tions of the five species of sea turtles, the National Marine Fisheries Ser- vice (NMFS) in about 1978 began to develop research and public-educa- tion programs aimed at decreasing sea turtle mortality in the Gulf of Mexico and southern Atlantic states. Guidelines for resuscitating and releasing turtles incidentally caught in their trawling operations were developed by NMFS and the active participation of shrimpers. Gear- research programs under the auspices of NMFS, Sea Grant, and the shrimping industry itself led to the development of several types of net installation devices that came to be called turtle excluder devices (TEDs) or, later, trawler efficiency devices. The only NMFS-approved TED in 1983 was an NMFS TED, and by early 1986, only certain versions of this device were approved. Because many fishermen were apprehensive about using TEDs in mid-1986, the
18 Decline of the Sea Turtles University of Georgia and NMFS tested industry designs at Cape Canaver- al. This resulted in NMFS certification of the Georgia, Cameron, and Matagorda TEDs. In the summer of 1987, the Morrison TED was certified, and an early version of the Parrish TED was tested. In the fall of 1987, a modified Parrish TED was certified. Each type of TED was intended to divert swimming turtles out of shrimp nets, thus excluding the turtles from the nets while not reducing the shrimp catch. Over about a decade of development, TEDs were light- ened and modified from the prototype. Today, six kinds have been aooroved bv NMFS for use on shrimp-trawling vessels (Appendix C). ~ 1 1 , Each TED has been repeatedly tested for effectiveness by NMFS, state agencies, and private shrimpers. By 1983, NMFS had tried a voluntary compliance program encouraging shrimpers to use TEDs, but few shrimpers responded. Instead, most shrimpers regarded TEDs as nuisances and remained unconvinced that the devices provided sufficient economic incentive in the form of catch purity. Some argued that TEDs would reduce their shrimp catches and that TEDs are expensive, dangerous, and time-consuming to install and clean all this adding to the monetary costs of shrimping. Primarily because of results of testing different TEDs under different conditions, both NMFS and environmental groups became convinced that TEDs effec- tively exclude turtles from shrimp nets and that their use does not result in a significant reduction in the shrimp catch. In fact, field tests in differ- ent areas indicated that the best TEDs sometimes reduced the incidental catch of turtles by up to 97% with little or no loss in the shrimp catch. A conflict arose almost immediately between proponents of TED regu- lations and the gulf shrimping industry. Shrimpers were not convinced that the turtles killed in shrimp trawls were responsible for the reported overall declines in sea turtle populations. They believed that something else was killing the turtles. Representatives of the industry in the gulf area categorically asserted that the imposition of TEDs on trawlers would reduce shrimp catch and devastate the industry. Several lawsuits were filed to delay the implementation of the NMFS regulations regarding TEDs. By 1985, it was apparent that relatively few shrimpers were using TEDs voluntarily. Faced with the threat of lawsuits to close down the shrimping industry, NMFS sponsored a series of mediation meetings in 1986 that included members of environmental organizations and shrimpers (Con- ner, 19871. The group agreed (with one abstention) to a negotiated rule- making that would phase in the required use of certified TEDs in specific areas at specific times. By 1987, however, grassroots pressure led to state and federal legislative attempts to delay the implementation of TED regu
19 Introduction rations, and some of the industry parties to the negotiated rulemaking repudiated the agreement (Conner, 1987~. After numerous debates, con- ferences, and public hearings over the years, NMFS developed by 1987 a final set of regulations on the use of TEDs by shrimp trawlers, to be implemented in 1989. The regulations including trawler size, geograph- ic zones, seasons, tow-time restrictions, exemptions, and starting dates" were publishedin the FederalRegisterE52 (1241:24247-24262, June 28, 19871. The controversy and concern over the deaths of turtles in trawl nets of shrimpers and the potential effects of the proposed regulations to protect turtles on the shrimping industry then motivated Congress to amend reau- thorization of the Endangered Species Act in 1988. One of the amend- ments to the reauthorization stipulated that a committee of the National Academy of Sciences should review the biology and behavior of the five species of sea turtles. Section 1008 of the Endangered Species Act Amendments of 1988 spec- ified the following issues for study: · Estimates of the status, size, age structure, and, where possible, sex structure of each of the relevant species of sea turtles. · The distribution and concentration, in terms of United States geo- graphic zones, of each of the relevant species of sea turtles. · The distribution and concentration of each of the relevant species or sea turtles, in the waters of the United States, Mexico, and other nations during the developmental, migratory, and reproductive phases of their lives. · Identification of all causes of mortality, in the waters and on the shores of the United States, Mexico, and other nations for each of the relevant species of sea turtles. · Estimates of the magnitude and significance of each of the identified causes of turtle mortality. · Estimates of the magnitude and significance of present and needed headstart or other programs designed to increase the production and population size of each of the relevant species of sea turtles. · Description of the measures taken by Mexico and other nations to conserve each of the relevant species of sea turtles in their waters and on their shores, along with a description of the efforts to enforce these measures and an assessment of the success of these measures. · Identification of nesting and/or reproductive locations for each of the relevant species of sea turtles in the waters and on the shores of the United States, Mexico, and other nations and of measures that
20 Decline of the Sea Turtles should be undertaken at each location, as well as description of worldwide efforts to protect such species of turtles. Accordingly, a study committee was convened by the National Re- search Council's Board on Environmental Studies and Toxicology in col- laboration with its Board on Biology. The committee included experts in international and domestic sea turtle biology and ecology, coastal zone development and management, commercial fisheries and gear technology, marine resources, and conservation biology. During the course of the committee's 1-year study, it heard from representatives of the shrimping industry, conservation organizations, the U.S. Fish and Wildlife Service, the National Marine Fisheries Service, and Sea Grant programs. The com- mittee observed shrimp trawling exercises with and without turtle exclud- er devices on a converted shrimp trawler in Georgia coastal waters. It reviewed pertinent published literature and analyzed original data sets on aerial and beach turtle surveys, shrimp trawling efforts, other commercial fisheries, turtle strandings, and other materials from a variety of organiza- tions and experienced individuals. The present report reviews available scientific and technical informa- tion on the biology, reproductive dynamics, behavior, and distribution of five species of sea turtles. It also describes and assesses the sources of mortality incurred by the species and the effectiveness of current and required conservation measures. The committee was not charged or con- stituted to address and did not analyze social and economic issues related to sea turtle conservation.