Shark tag team dive in
Scientists study grand marine canyons
MARITIME researchers and students are back from collecting special retrievers that will help them investigate the movements of tagged sharks off the South Coast.
They dropped the retrievers – or listening stations – down 80m to 90m in the newly announced Protea Banks marine protected area, which is 7.5km out to sea from Shelly Beach.
Their research is expected to confirm Protea Banks’ canyon heads as an important shark habitat, according to conservation body WildOceans.
WildOceans executive director Jean Harris said this study was the first of its kind in South Africa.
“The aim is to study the movement of sharks along the KwaZulu-Natal coast,” said Harris.
“This part of the project, led by Dr Matt Dicken of the KwaZulu-Natal Sharks Board, aims to understand the importance of canyon heads as critical habitat for sharks, especially species such as tiger, ragged-tooth and Zambezi.
“We are especially interested in understanding the role submarine canyons play as productive nodes in the seascape and the connectivity with shallower inshore habitats.
“The receivers we retrieved and replaced are deeper, 80m to 90m down, at canyon heads. Due to the depth of these sites, the receivers have acoustic releases that can be remotely activated from the surface.”
The researchers sailed out on WildOceans’ research vessel RV Angra Pequena.
Ezemvelo KZN Wildlife scientist Tembisa Jordaan, who observed the telemetry retrieval, said divers reported a massive shark aggregation in the area of the ocean.
The data collection follows a WildOceans survey of scalloped hammerhead sharks at Protea Banks in December and January.
“As this species has only been tagged in Mozambique, if we picked up any signals for this species on our receivers this would show there is a connection between sites in Mozambique and this big aggregation in southern KZN, and that the sharks are moving between them,” said Harris, adding that it would be exciting if they were recorded on the Protea Banks receivers.