THE CONSERVATION CONCERNS
Like reptiles from a bygone era the seven species of sea turtles swim through Earth’s oceans today just as they did one hundred million years ago. Despite having survived the mass extinction of the dinosaurs, they are not indestructible. Today they face an arguably more perilous existence at the hand of man and their numbers have drastically reduced dangerously close to the point of collapse. |
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 Adult turtle caught on a line |
Sea turtles have a priority for conservation through their listing in the Convention on the Conservation on Migratory species (CMS), the Convention on international Trade in Endangered species of wild fauna and flora (CITES-appendix 1) and the World Conservation Union (IUCN) as either endangered or critically endangered (IUCN- EARO and IUCN/SSC, 1996).
“I knew the loggerhead turtle was an endangered species, but I knew nothing of the specifics. I was captivated by the resilience of these extraordinary creatures. From the moment she is born, the tiny turtle is forced to fight for survival. Against all odds, the loggerhead has avoided extinction and has continued to travel the same route through the ocean since pre-historic times.”
Miranda Richardson, narrator of Turtle: The Incredible Journey
HABITAT ALTERATION AND LOSS
Beach armoring – eliminates nesting habitats
It consists of hundreds of hardened structures, including concrete sea walls, rocks and sandbags, meant to protect dune property from erosion. It is unknown whether sea turtles kept from nesting at armoured beaches may forgo nesting altogether or move to adjacent suitable nesting beaches.
Beach nourishment and sand mining
Beach nourishment involves mechanically dumping or pumping sand onto an eroded beach. This replaces rather than maintains the original nesting habitat, and the suitability of the consequently renourished habitat for sea turtle nesting depends on the quality of fill material and methods used to deposit it. If there is a high content of clay, silt, and shell the beaches are too compact for nest excavation. Steep banks often form on nourished beaches, preventing turtles from making it above the tide mark. Even if an egg chamber is dug in the right place the substrate, which differs to a natural beach, often negatively affects the architecture – resulting in lower egg and hatchling survivorship.
Beach driving
Vehicles can crush developing eggs and pre-emergent hatchlings, and the tire ruts can trap hatchlings in the sand, exhausting them and making them even more vulnerable to predators. Loggerhead hatchlings can escape from a 3-cm-deep footprint, but not from a tire rut of the same depth. At night vehicles disturb nesting females and crush hatchlings on their way to the water.
Human presence on the beach
Foot traffic can also damage eggs and hatchlings, and uncontrolled visitations at night can cause turtles to abort nesting attempts.
Artificial lighting
Artificial lighting causes chaos in a turtle’s world. It can affect the choice of nesting sites, deter females from even nesting at their chosen beach, and confuse adult females on their way back to the ocean. For a hatchling emerging from the darkness of the egg chamber any lights on the beach become a vision minefield. At night the ocean reflects light from the moon and the atmosphere, making it the brightest area in their field of vision under natural conditions. Hatchlings instinctively head towards it, but artificial lights disorientate them and lead them away from the ocean towards the light itself. Hatchlings have even been known to wander into bars, and soon succumb to exhaustion, dehydration, and predation.
Boast strikes
Countless numbers of loggerhead turtles are killed by boats every year in the USA alone.
Dredging, explosive platform removal
Dredge and fill operations occur in many of the nearshore seasonal habitats of sea turtles worldwide. The scale of these activities ranges from the propellers from recreational boats to the dredging of channels and fill for land reclamations.
Underwater explosions of any kind, from those detonated to remove oil and gas platforms to military maneuvers with explosives have huge potential to harm sea turtles. They cause capillary damage, disorientation, and loss of motor control. Turtles exposed to this normally sustain fatal injuries.
DESTRUCTION OF SEA TURTLE NESTS
Feral hogs, pigs, foxes, coyotes, mongooses and domestic dogs can completely destroy a nest of turtle eggs.
Oil pollution
Oil spills washed up on the beach interfere with the normal development of the embryos and becomes a lethal hazard to newly emerged hatchlings. At sea oil and tar pollution at the surface of the ocean presents even more enormous problems for sea turtles. The Sargasso Sea, where the loggerhead in the film Turtle travels, alone entraps an estimated 70,000 metric tons of tar. Sea turtle juveniles travelling the open ocean on currents are often in ocean convergent zones and drift lines, regions where floating tar accumulates. Surfacing to breathe through an oil slick means inhaling petroleum vapor into their lungs, and petroleum ingested from contaminated food or tar balls poisons sea turtles.
Heavy metal pollution
Sea turtles, like fish and marine mammals, can accumulate heavy metals and pesticides in their bodies, and chronic pollution from industrial, agricultural wastes, and urban runoff is a big threat to them.
PLASTICS AND NON-BIODEGRADABLE DEBRIS LITTER OUR ALL OF OUR OCEANS
Rubbish from boats, ships, offshore oil, gas and chemical platforms and from land makes up marine debris.
Ingestion
All species and all ages of sea turtles are affected by ingesting debris. A more concentrated soup of debris faces the juveniles who feed indiscriminately and swim at the mercy of convergence zones and also adults who travel on these fronts. Ingestion of foreign debris can cause a complete blockage in the gut, resulting in starvation and death.
RUBBISH FOUND IN TURTLE DIGESTIVE TRACKS:
- Plastic bags (often mistaken for a jellyfish!)
- Plastics of all kinds
- Sheeting
- Beads
- Pellets
- Line
- Rope
- Strapping
- Pieces from bottles
- Hard pieces of plastic
- Latex balloons
- Aluminium
- Paper
- Cardboard
- Styrofoam
- Rubber
- String
- Cigarette filters
- Wax
- Cellophane
- Fish hooks
- Charcoal
- Glass
Entanglement
Entanglement in abandoned and lost fishing gear is a serious problem for sea turtles. It often results in reduced mobility, making the turtle more vulnerable to predators. Being entangled at the surface makes them more susceptible to boat collisions and dragging debris puts them at risk from drowning. Nets, ropes and plastic 6-pack holders can end up around their necks or around flippers, leading to infection, severing limbs and death.
THINGS THAT ENTANGLE TURTLES
Plastics are the most common
Fishing gear (monofilament line may account for 68% of entanglement cases)
Plastic-fiber bags
Sheeting
Strapping
Cloth
Plastic 6-pack holders
Steel cable
Aluminium beach lounge chairs
Polypropylene rope
Fishing and Incidental Capture
Incidental capture in shrimp trawls is believed to account for more deaths of sea turtles than any other human-induced source. Before protective measures were implemented between 5,000 - 50,000 loggerheads were thought to be killed each year by drowning in shrimp trawls. Other fishing methods, such as purse seine and gill nets also kill turtles.
Shrimp Trawling and Turtle Excluder Devices (TEDs)
TEDs allow captured sea turtles to escape from the trawl nets through a specially fitted escape hatch. In one southern US state the use of TEDs is believed to have reduced annual loggerhead deaths by 44%. If turtles are repeatedly caught, however, their chances of survival are considerably lowered due to the stress they endure. Without compliance across all our oceans the protective measures in one country will be undone in another if fishing practices are unrestricted. Sea turtles are highly migratory and it is critical that measures such as TEDs, which reduce turtle deaths, be used by every shrimp-fishing nation in the world.
Pelagic (open ocean) fishing gear
Pelagic fishing gear includes longlines, trawls and gill net fisheries. Sea turtles are attracted to the innumerable number of 100 km-long lines of baited hooks in the ocean that are set for swordfish, tuna or sharks and often end up drowning on the end of the line. Even if they are successfully freed from the hooks, sea turtles may die later from hook wounds, internal bleeding or entanglement.
Coastal fishing activities
Inshore fisheries combined with unattended nets set in shallow waters are the second largest source responsible for the deaths of sea turtles.
Artisanal and commercial sea turtle fisheries
Commercial and subsistence sea turtle fisheries around the world, but particularly in developing countries, are also responsible for the worldwide decline of nearly all sea turtle populations and have resulted in the local extinctions of some populations. Breeding adults and their eggs are the most vulnerable, but all life stages are exploited. Turtles are caught for protein and turtle by-products (both the body and shell) are sold as curious for the tourist trade. Hawksbill shells in particular are in demand for their shells, which are made into ornaments and jewelry. The Endangered Species Act of 1973 prevents the commercial harvesting of sea turtles in US waters.
All species of sea turtles are listed on Appendix I by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). This listing makes international trade in sea turtle parts or products illegal under the CITES agreement.
Reference Source: The Biology of Sea Turtles, Edited by Peter Lutz and John Musick. CRC Press, 1997. PP. 432