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Each year thousands of hatchling turtles emerge from their nests along
the southeast U.S. coast and enter the Atlantic ocean. Sadly, only an
estimated one in 1,000 to 10,000 will survive to adulthood. The natural
obstacles faced by young and adult sea turtles are staggering, but it is
the increasing threats caused by humans that are driving them to
extinction. Today, all sea turtles found in U.S. waters are federally
listed as endangered, except for the loggerhead which is listed as
threatened.
NATURAL THREATS
In nature, sea turtles face a host of life and death obstacles to their
survival. Predators such as raccoons, crabs and ants raid eggs and
hatchlings still in the nest. Once they emerge, hatchlings make
bite-sized meals for birds, crabs and a host of predators in the ocean.
After reaching adulthood, sea turtles are relatively immune to
predation, except for the occasional shark attack. These natural
threats, however, are not the reasons sea turtle populations have
plummeted toward extinction. To understand what really threatens sea
turtle survival, we must look at the actions of humans.
HUMAN-CAUSED THREATS
In many cultures around the world, people still harvest sea turtle eggs
for consumption. Most countries forbid the taking of eggs, but
enforcement is lax, poaching is rampant, and the eggs can often be found
for sale in local markets. In these same areas, adult sea turtles are
harvested for their meat. Turtle products, such as jewelry made from
hawksbill shells, also create a direct threat to sea turtles. Lack of
information about sea turtles leads many Americans to unwittingly
support the international trade in these endangered species. Buying and
selling turtle products within the U.S. is strictly prohibited by law,
but turtle shell jewelry and souvenirs are the most frequent contraband
seized by customs officials from tourists returning from the Caribbean.
Indirect threats are harder to quantify, but they are likely causing the
greatest harm to sea turtle survival.
COMMERCIAL FISHING
The waters of the Gulf of Mexico and west Atlantic coast are a major
habitat for turtles, but are also the main shrimping grounds in the U.S.
Each year, thousands of turtles become entangled in fishing nets and
drown.
Worldwide, shrimp trawling probably accounts for the incidental death of
more juvenile and adult sea turtles than any other source. At one time,
as many as 55,000 sea turtles were killed each year in shrimp nets in
the southeastern United States alone. Today, all U.S. shrimpers are
required to put Turtle Excluder Devices (TEDs) in their trawl nets.
Unfortunately, not all fishermen comply with the law, and sea turtles
continue to drown in shrimp nets.
INGESTION OF DEBRIS AND PLASTIC
Thousands of sea turtles die from eating or becoming entangled in
non-degradable debris each year, including packing bands, balloons,
pellets, bottles, vinyl films, tar balls, and styrofoam. Trash,
particularly plastic bags thrown overboard from boats or dumped near
beaches and swept out to sea, is eaten by turtles and becomes a deadly
meal. Leatherbacks especially, cannot distinguish between floating
jellyfish — a main component of their diet — and floating plastic bags.
ARTIFICIAL LIGHTING
Nesting turtles once had no trouble finding a quiet, dark beach on which
to nest, but now they must compete with tourists, businesses and coastal
residents for use of the beach. U.S. beaches are rapidly being lined
with seaside condominiums, houses and hotels. Lights from these
developments discourage females from nesting and cause hatchlings to
become disoriented and wander inland, where they often die of
dehydration or predation.
COASTAL ARMORING
Coastal armoring includes structures such as sea walls, rock revetments
and sandbags that are installed in an attempt to protect beachfront
property from erosion. These structures often block female turtles from
reaching suitable nesting habitat and accelerate erosion down the beach.
Armoring is especially problematic along the east coast of Florida,
where beach development is occurring in the very places where sea
turtles come to nest by the thousands.
BEACH NOURISHMENT
Beach nourishment consists of pumping, trucking or otherwise depositing
sand on a beach to replace what has been lost to erosion. While beach
nourishment is often preferable to armoring, it can negatively impact
sea turtles if the sand is too compacted for turtles to nest in or if
the sand imported is drastically different from native beach sediments,
thereby potentially affecting nest-site selection, digging behavior,
incubation temperature and the moisture content of nests. If
renourishment is allowed to proceed during nesting season, nests can
also be buried far beneath the surface or run over by heavy machinery.
POLLUTION
Pollution can have serious impacts on both sea turtles and the food they
eat. New research suggests that a disease now killing many sea turtles (fibropapillomas)
may be linked to pollution in the oceans and in nearshore waters. When
pollution kills aquatic plant and animal life, it also takes away the
food sea turtles eat. Oil spills, urban runoff of chemicals, fertilizers
and petroleum all contribute to water pollution.
Although the problems of habitat destruction and exploitation seem
almost too big to overcome, there are many things within our control
that can be changed. Greater public awareness and support for sea turtle
conservation is the first priority. By learning more about sea turtles
and the threats they face, you can help by alerting decision-makers when
various issues need to be addressed.
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