4:00AM Friday Mar 13, 2009
By Kathy Marks
Turtles go to South America and back. Photo / AP
SYDNEY - Marine biologists believe they have found the answer to a long-standing question: what do endangered loggerhead turtles get up to after hatching on an Australian beach?
Apparently they hitch a lift on ocean currents from Queensland across the Pacific to South America and back again - a round trip of more than 19,000km.
The migratory behaviour of the juvenile turtles was confirmed by marine biologists at Queensland's James Cook University, who did genetic testing on loggerheads found stranded on the Australian coast and captured by long-line fishing vessels off Peru. Turtles at the two locations shared the same genetic background.
While loggerheads can be found around the world, scientists are particularly anxious to find out more about the Queensland population, which has declined by up to 80 per cent over the past decade. The latest study has helped fill in the lost years of the juveniles, whose early movements were a mystery until recently.
The study, published in the Proceedings of the Royal Society B, tracks the turtles from the time they emerge from their nests on Mon Repos beach in southern Queensland.
First, baby turtles head for the water and swim out to sea, according to lead researcher Dr Michelle Boyle. Then, like the turtles in Finding Nemo, they hitch a ride south on the East Australian Current, taking them towards Sydney.
From there, the loggerheads travel east, passing Lord Howe Island, then the northern tip of New Zealand. They pick up the Humboldt Current, traversing the South Pacific to the coast of Peru and Chile. Later, they return to Queensland using the Southern Equatorial Current, researchers suggest.
In her paper, Boyle says many questions remain. It is unclear how long the odyssey takes and whether the loggerheads spend most of their time swimming or floating in with the currents.
While the population in eastern Australia has declined dramatically, its prospects look slightly better than a few years ago thanks to improved protection and the compulsory use of trawl nets designed to allow captured turtles to escape.
- INDEPENDENT
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