In an Australian first, two Loggerhead Turtles were fitted with satellite trackers at Taronga Zoo and released off the shores of Lord Howe Island in an attempt to unlock the migration secrets of this endangered marine animal.
After being handed in to the Department of Environment and Conservation, Taronga Wildlife Hospital has been caring for the two young turtles since April last year until they reached a size that would give them the best chance of survival when released into the ocean.
Taronga has nursed numerous turtles over the years, however never before have satellite trackers been available to chart the course of the patients once they have left human care.
Taronga Wildlife Hospital Manager, Libby Hall, said: “Very little is known about the journey of Loggerhead Turtles once they leave Australia. They hatch on beaches in Queensland and make their way into the ocean spending more than 30 years at sea before returning to the same beach to lay their eggs. Where they go, and what they do during those years is somewhat of a mystery.”
The juvenile years of turtles are known as the ‘Lost Years’. Until recently it was thought that turtles were swept along with the ocean currents, but research conducted in the North Pacific has revealed that turtles are not just passive passengers but could be some of nature’s most accomplished navigators.
“Thanks to a specialised diet of pilchards, squid and shellfish the turtles both now tip the scales at over six kilograms and are just a bit longer than a standard 30 centimetre ruler, making them the ideal size to send on their ocean voyage. But this time we will be able to keep an eye on them thanks to small satellite trackers on their backs,” said Libby.
The trackers that will help chart the course of the two turtles have been donated by world-renowned turtle researcher, George Balazs from the National Marine Fisheries Service in Honolulu. He is the leading authority on mapping turtle movements, having tracked this ancient species in numerous areas including the Hawaiian Islands, the Gulf of Mexico and North Pacific Oceans. Balazs will assist Taronga Wildlife staff Kimberly Vinette Herrin and Libby Hall in fitting the satellite trackers to the endangered marine creatures before sending them on their ocean journey.
The turtles were flown on a Qantas jet to Lord Howe where Taronga staff released the Loggerheads off the coast. They were released into the pathway of the Eastern Australian Current at a point where it meets the Tasman Drift, enabling the turtles to head north and join their cohorts.
Via the satellites on their back, the Loggerheads will literally log-in daily, sending data on their location to the Taronga Wildlife Hospital and George Balazs.
The implications of the research could be huge. Similar studies conducted off foreign shores have played a vital role in protecting various marine species. Main threats to turtles include entanglement in fishing nets and accidental by-catch of long-line fishing, whilst boat strikes are also common.
“By charting their movements and creating ‘turtle maps’ researchers in the North Pacific have worked with fishing companies to ensure long line fishing is limited in certain areas of the ocean at certain times of year to ensure turtles are not accidentally harmed,” Libby Hall said.
“If we knew how the turtles used the ocean currents and where they swim there is a much greater chance of protecting dwindling populations. As an endangered species, every single individual is invaluable”.
There are seven species of marine turtles in the world and six occur in Australian waters. All six species have suffered population declines as a result of pollution, entanglement in fishing nets, plastic bag ingestion, depletion of food stocks, boat-related injuries, loss of shoreline breeding areas and egg predation by species such as foxes and dogs.
Marine turtles are recognised internationally as a species of conservation concern and are listed in the World Conservation Union Red List of Threatened Animals.