THREATS TO SEA TURTLES: ABACO, BAHAMAS… IN FACT, EVERYWHERE
The Bahamas has breeding populations of 5 of the world’s 7 sea turtle species – Green, Loggerhead, Hawksbill, Leatherback and Kemp’s Ridley turtles (the other two are Olive Ridley – occasionally found in the Bahamas – and Flatback turtles). All are endangered. There’s no getting away from the fact that Man and Man’s activities are now the primary threats. The IUCN ratings below make for sad reading.
GREEN TURTLE (Chelonia mydas)
HAWKSBILL TURTLE (Eretmochelys imbricata)
Hunted almost to extinction for their shells
LOGGERHEAD TURTLE (Caretta caretta)
LEATHERBACK TURTLE (Dermochelys coriacea)
The largest sea turtle
KEMP’S RIDLEY TURTLE (Lepidochelys kempii)
The smallest sea turtle
A helpful source of information about sea turtles and their protection is the BAHAMAS SEA TURTLE CONSERVATION GROUP Their excellent summary of the multiple threats to these creatures (below) puts the critical situation very well. Anyone who has watched a TV program about sea turtles and their breeding will be familiar with the vulnerability of turtle nests and hatchlings to predation – and that’s before they ever get to the sea. Despite that, all the species managed to flourish until human intervention (direct or indirect) tipped the balance of survival much further against them. So if we lose one or more of these wonderful species, at least we’ll know who to blame.
1. 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.
2. 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.
Illegal turtle shells (IUCN)
3. 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.
4. 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 (my italics).
One sea turtle’s accumulated ingested plasticCredit: http://www.wired.com/wiredscience
5. 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.
6. 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.
7. 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 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.
“Look on thy works, ye Humans, and despair…” [Gulf of Mexico]Credits boston.com / Reuters
FURTHER REFERENCES (click logos)
- Green Turtle (Chelonia mydas)
- Hawksbill Turtle (Eretmochelys imbricata)
- Loggerhead Turtle (Caretta caretta)
Credits: BSTCG; Wiki (images / IUCN tables); wire.com / wiredscience; Boston.com; Reuters; NASA; STC