EZEMVELO KWAZULU-NATAL WILDLIFE
MEDIA RELEASE No: 2009 - 11
In mid-January 2009 a team comprising members of Ezemvelo KZN Wildlife (EKZNW), the Marine and Coastal Management (MCM) section of the national Department of Environment Affairs (DEA), and researchers from the Nelson Mandela Metropolitan University(NMMU), fitted satellite tracking transmitters to three female leatherback sea-turtles on the beaches of the iSimangaliso Wetland Park north of Sodwana Bay.
As leatherback sea-turtles are extremely powerful animals and are swift swimmers, the only opportunity to fit the harnesses was during a female’s on-shore egg-laying activities when she would lie quite still for about 45 minutes.
Each transmitter was strapped onto a sea-turtle using a carefully constructed harness of approved international design built to avoid any interference with the turtle’s movements and to avoid possible chafing.
As the transmitters were fitted in mid-January each sea-turtle nested at least once more after the fitting, before moving off to begin their migration which was the reason for the tracking exercise.
The information gained during the period between nestings provided valuable insights about the animals’ movements inshore.
Once the final egg-laying had taken place, the satellite tracking provided interesting movement records as no- one knows quite where the leatherback sea-turtles that nest on the Zululand beaches go to between nesting seasons, hence the study.
One sea-turtle moved initially northwards towards the Mozambique Channel, while the other two moved southwards, as had sea-turtles from previous tracking operations.
One of the southbound turtles remained relatively close inshore apart from a few forays way out to sea, while the other seemed initially to prefer deep, open ocean.
The signal from the animal moving towards the Mozambique Channel indicated that it had turned south of Madagascar and after a great many swoops and circles headed east and is presently east of Reunion Island and Mauritius about 150 km from the island of Rodriguez.
The other two sea-turtles moved close inshore along the Cape south coast, one being just past Port Elizabeth and the other beyond the Tzitzikamma National Park.
Signals from both these animals have, unfortunately, subsequently ceased.
A signal from a leatherback sea-turtle tagged during the previous nesting season in January 2008 also reappeared off St Helena Island just over a year after leaving the beaches of the iSimangaliso Wetland Park.
This particular animal was thought to have been lost until the satellite began to pick up her signal again after a considerable period of silence had elapsed.
This signal has since ceased, probably due to battery-failure in the transmitter.
Almost all previous tracking projects have shown that the leatherback sea-turtles move around the Cape and head up in to the Atlantic Ocean, with the signals ceasing way out to sea off southern Angola.
This tracking project complements Ezemvelo KZN Wildlife Sea-turtle project which is now the longest running leatherback and loggerhead turtle monitoring project in the world, having been started under the former Natal Parks Board in 1963 and which has enjoyed valuable financial support from its main sponsor WWF (SA).
Steel components of the harness holding the satellite transmitting device are designed to rust away allowing the rig to drop off the animal after about a year.