29 October 2010

Turtles set for release back into the ocean

Two Oceans Aquarium
A baby loggerhead turtle

Nineteen juvenile loggerhead turtles took to the skies on Wednesday, 27 October, courtesy of our official animal carrier, 1time Airline. They’re destined for release into the warm waters of the Indian Ocean, in a collaborative effort between the Aquarium and Durban’s uShaka Marine World.

All the turtles were found stranded on beaches around the Cape Peninsula and brought to the Aquarium by concerned residents. Being warm water inhabitants, these turtles were probably swept down from the northern coast of KwaZulu-Natal (where they hatch) by the mighty Agulhas Current and washed ashore by stormy seas.

When they arrived at the Aquarium they were weak, having been exposed to cold water, and were invariably suffering from dehydration.

This is an annual occurrence and so the Aquarium is accustomed to receiving the hatchlings.

“We encourage people to bring the turtles to the Aquarium where we will rehabilitate them and once they are strong enough ... release them back into the Indian Ocean,” says Two Oceans Aquarium Communications and Sustainability Manager Helen Lockhart.

While loggerheads are the most common species of turtles off the coast of Southern Africa, they are currently listed as endangered on the International Union for Conservation of Nature’s Red Data List. This means that they are at a very high risk of extinction in the wild.

Loggerhead turtles feed predominantly on sea urchins, molluscs and hermit crabs, which they crush with their powerful jaws. Females nest on the northern beaches of KwaZulu-Natal and lay 100 to 120 eggs every 15 days during summer.

The temperature of the sand determines the gender of the hatchling turtles. If the temperature is between 20 and 24˚C, the hatchlings will mostly be male. If temperatures are 29˚C or higher, the hatchlings will mainly be female.

Males never return to land after having hatched, and only one in a 1 000 hatchlings will survive to maturity. Adults weigh up to 125 kilograms and measure up to 1.2 metres in length.

Sea turtles are living dinosaurs, having survived some 90-million years, yet all seven species of turtle are threatened with extinction. This is largely due to various human activities and the loss of nesting habitats. Increased human presence on beaches, particularly at night, disrupts nesting females, who may be forced to use less suitable sites or abort egg laying completely. Recreational activities on beaches along with umbrellas, deck chairs, small boats and 4x4 vehicles damage potential nesting sites and even destroy existing nests.

Poaching ranks as another major threat. Nests are raided for the eggs, which provide food for the local people.

The ingestion of litter, particularly plastic, has serious and lethal consequences for turtles. All hatchling turtles eat jellyfish and often mistake plastic bags for food. Plastic is not only toxic, but also obstructs the stomach and prevents the turtle from getting nutrition from its food. The result is a lingering death.

Other threats include artificial lighting from buildings and street lights, which disorient hatchlings; the building of sea walls and jetties; beach erosion; beach cleaning; commercial fishing (turtles are accidentally caught up in gill nets) and oil and gas exploration.

Hatchlings are particularly vulnerable to nature’s predators as they make their way from the nest to the sea. Gulls, mongooses, leguaans, crabs, and even ants attack the baby turtles. Once in the sea, large fish also prey on them.

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