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Sea Turtles Fact Sheet
What Are Sea Turtles And Where Do They Live?
Sea turtles are air-breathing reptiles whose limbs have evolved over time
into flippers for swimming in the ocean. Well-adapted to their marine habitat,
sea turtles are proficient swimmers and often travel thousands of miles between
nesting beaches and feeding or wintering areas. There are seven species of sea
turtles worldwide--green, loggerhead, olive ridley, Kemp's ridley, hawksbill,
and leatherback. Five of these--the green, loggerhead, leatherback, Kemp's
ridley, and hawksbill--are found In U.S. waters in the Atlantic Ocean and Gulf
of Mexico. With the exception of the Kemp's ridley, these species also occur
along our southern Pacific coast along with the olive ridley. They vary widely
in size, from the small, critically endangered Kemp's ridley, with adults
weighing between 80 and 100 pounds (36-45 kg), to the 1000+ pound (453 kg)
leatherback.
What Makes Them Unique?
Sea turtles spend their entire lives at sea, except when the females come
ashore to lay eggs. Every 2-5 years female turtles come ashore to nest 3-6 times
in a season, laying roughly 100 ping pong ball-sized eggs each time. After
approximately 60 days of incubation, the hatchlings emerge together at night and
make their way to the ocean, attracted by the brightness of horizon. Raccoons,
foxes, ghost crabs and erosion are some of the perils the eggs must survive to
hatch and reach the sea. Once in the sea, the tiny hatchlings may fall prey to
sharks, a variety of fish, and seagulls and other birds. Those that survive are
swept into areas where ocean currents come together, along with seaweeds and
other potential food sources. The hatchlings spend the first several years of
their lives in the open ocean, eventually moving to protected bays and
estuaries. Most sea turtles are probably 20 to 30 years old or more before they
begin breeding.
Sea turtles consume variety of foods. The green sea turtle is a vegetarian,
feeding mostly on sea grasses and algae, while the hawksbill feeds on sponges --
consuming even the glass skeletons that support the sponges. Crabs are a
favorite food of the Kemp's ridley, the giant leatherback eats mostly jellyfish,
and the loggerhead feeds on a variety of shellfish, sponges, and jellyfish.
How Many Sea Turtles Are Left In The World?
Sea turtles have been on Earth for more than 100 million years, surviving
even the disappearance of the dinosaurs. Yet now, all six species of sea turtles
in U.S. waters are threatened or endangered and are protected under the United
States Endangered Species Act (ESA). The Kemp's ridley is most critically
endangered, with a population that exceeded 42,000 nesting females in 1947. That
number has dropped to fewer than 1,500 today. Other species of sea turtles have
also experienced major population declines--though none as dramatic--for a
number of reasons.
Why Are Sea Turtle Populations Endangered?
Shrimp Trawling: A 1990 study by a National
Academy of Sciences panel reported that drowning in shrimp trawls is
the greatest source of human-caused mortality for sea turtles in U.S.
waters, estimating that, without preventative measures, as many as
55,000 may drown every year. The study concluded that shrimp trawling
could be compatible with sea turtle conservation with the mandatory
use of turtle excluder devices (TEDS) - trap-door mechanisms installed
in shrimp trawls that allow 97% of sea turtles to escape unharmed.
TEDs are now required in all southeastern shrimp trawls year-round, a
solution which allows continued shrimping while still protecting
endangered sea turtles.
Fisheries: Longline fisheries for tunas, swordfish and billfish
catch an undetermined number of sea turtles each year, while
multi-species gillnet fishing in areas where young turtles feed
continues to drown sea turtles. TEDs have been successfully adapted to
work in other trawl fisheries such as summer flounder fisheries.
Habitat Loss: Due to the tremendous demand for beachfront property
throughout the Southeast, sea turtle nesting and feeding habitat is
being rapidly replaced by seawalls, condominiums and hotels. Coastal
development not only discourages females from coming ashore to nest
but artificial lighting from cars, buildings, and streetlights
disorients newly emerged hatchlings, attracting them away from, rather
than toward, the ocean.
Dredging: Sea turtles can be caught and crushed in certain types
of dredges. During a single month in 1991, as many as 17 turtles were
killed at one site off the coast of Georgia. The judicious restriction
of hopper dredges to times and places where turtles are not active has
greatly reduced the problem, while still allowing other types of
dredges to operate at these times.
Pollution: Sea turtles often become entangled in discarded debris
such as driftnets, rope, and fishing line. Plastic is often mistaken
for food, and once ingested can choke sea turtles or clog their
digestive system. It has been suggested that leatherbacks, for
example, may mistake plastic bags for jellyfish, their favorite food.
What Does This Tell Us?
Because of their slow maturity -- green turtles may be in their
fifties before they begin to reproduce -- sea turtles are especially
vulnerable to human encroachment, and thus we should heed what they
tell us about the health of the marine environment. For example, the
harmful effects of shrimp trawling are not limited to sea turtles. In
fact, sea turtles comprise only a small portion of the "bycatch" of
most shrimp trawls. On the average, more than 80 percent of the catch
from a typical shrimp trawl consists of juvenile fish that will never
reach harvestable or reproductive size, as most bycatch is discarded
dead. Commercial yields of many of the same fish species have been
declining. It has been estimated that, if bycatch in the shrimp
fishery were eliminated, commercial catches of red snapper might
increase 60 to 90 percent, king mackerel by 20 to 30 percent; and
Spanish mackerel by 40 to 50 percent. Some types of TEDs can help
reduce this finfish bycatch significantly.
What Has Been Done To Protect Sea Turtles?
As required by the ESA, recovery plans have been developed to
protect and restore all five species of sea turtles in southeastern
U.S. waters. Plans are now being drafted for U.S. Pacific sea turtles.
In addition, all sea turtles are listed under Appendix I of the
Convention on International Trade of Endangered Species (CITES) and
consequently receive protection from International trade by all the
nations who signed the treaty.
A major step forward for sea turtle protection occurred in December
1992, when regulations requiring TEDs in all southeastern U.S. shrimp
trawls were finalized. The TED rules were further revised in December
of 1996 when less effective soft TEDs were decertified and TEDs were
required in try nets (small nets used to determine the location of
shrimp). The Center for Marine Conservation (CMC) worked for more than
fifteen years to achieve these goals. The safeguards afforded by TEDs
requirements are a major ESA success story since TEDs allow shrimpers
to continue trawling while still protecting sea turtles. Many Central
and South American countries are also starting to require TEDs.
Following nearly a decade of pressure from the conservation
community, 1992 marked the end of Japanese trade in tortoise shell
jewelry (from hawksbills) and other artifacts on the world market,
again precipitated by CMC's documentation of the magnitude of the
problem and its advocacy to end the trade.
Additionally, given the evidence of turtle deaths in hopper
dredges, after CMC's recommendations, hopper dredging is now
restricted to certain times of the year when sea turtles are not
likely to be present and requires preceding sea turtle surveys.
There have been many efforts to protect important nesting habitat,
ranging from beach patrols to protect nesting turtles and their eggs
to local lighting ordinances that help reduce disorientation of
hatchlings and nesting adults. The Archie Carr National Wildlife
Refuge, created In 1990 along the east-central coast of Florida, is
the first mainland U.S. national refuge established specifically for
sea turtle nesting. CMC played a major role in getting this refuge
established and has been working with federal, state, and county
officials to ensure purchase of key tracts of land for the refuge and
development of an interagency cooperative management plan for the
refuge.
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