|
All seven species of sea turtle worldwide are either
threatened or endangered and are protected on local and federal levels. The
global decline in sea turtle numbers is due to many causes, including
habitat destruction, coastal development, and the poaching of eggs and adult
turtles. Historically, the poaching and harvesting of turtles for meat,
shells, jewelry, and other products was a leading cause of sea turtle
mortality, and contributed greatly to the decline in turtle numbers. With
increased protection, education, and the implementation of conservation
programs as well as improvements in socioeconomic conditions, this has
changed.
Another major contributor to sea turtle deaths
historically has been the fishing industry. Hundreds of thousands of turtles
have been caught as by-catch, or incidental catch, by the shrimp fisheries.
Turtles caught in shrimp nets were injured, drowned or crushed by
machinery. The massive destruction to turtle populations resulted in the
development of the TED, or turtle excluder device. TED’s are now mandatory
for shrimp boats and serve as an escape hatch for turtles, allowing them to
safely exit the net. Although this situation has improved, other commercial
fishing practices, such as longlining, are currently responsible for high
rates of at-sea turtle mortality. Turtles are commonly caught, entangled,
or foul-hooked by lines and drown. As a result, longlining has been banned
in many areas. Scientists are also currently investigating the use of
different types of hooks for commercial fisheries. This might decrease the
amount of bycatch and foul-hooking incidents, while still yielding a good
catch for the target fish species.
Boat strikes are another common cause of sea turtle
death. Sea turtles will come to the surface to breathe, or bask, and are
vulnerable to passing |
|
boats. Propeller wounds, and related deaths are a
major cause of sea turtle mortality, and injuries are common, even in the
waters of the U.S. Virgin Islands. Boaters should be aware and use caution,
especially during nesting seasons from April through December. Any sick,
dead, or injured turtles may be reported to STAR, the sea turtle assistance
and rescue network at 1-877-3TURTLE.
Another important cause of sea turtle mortality is
fibropapillomas, large tumors that inhibit a turtle’s ability to see, eat,
and swim. These tumors, which are caused by a virus, may also be internal
and affect organ function. In some areas, such as Florida and Hawaii,
fibropapillomas have become an epidemic. Although turtles with
fibropapilloma are rare in our waters, 40% of the green turtle nesting
population in Culebra exhibit these tumors, and the problem is spreading.
The cause of this disease has not yet been determined, but may be attributed
to water pollution. Scientists from numerous organizations and universities
are currently studying this disease in the attempt to find not only the
cause, but a cure.
Additional causes of mortality may result from
pollution and debris in the water. Debris such as plastic bags, fishing
line, styrofoam and other objects may be ingested and result in death.
Turtles may also become entangled in debris, such as fishing line, collect
further debris while trying to swim, and eventually drown. There are many
human-related causes of sea turtle mortality that have contributed to the
decline in local and global numbers. To ensure the survival of these
magnificent animals, we must be aware of these causes and our impact on sea
turtle populations. Education and awareness, along with conservation
practices are vital to ensuring that sea turtles persist for future
generations. |
