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What is the leading cause of death for sea turtles?

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.  TEDís 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 turtleís 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.



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