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OCR for page 16
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
OCR for page 17
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
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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
OCR for page 19
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
OCR for page 20
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.
Representative terms from entire chapter:
relevant species
