CALL OUT
On Saturday the 25th of November a deceased white shark was reported to the South African Shark Conservancy by Ichthyologist, Sarah Halse, from the Breede area. On Sunday the 26th, Dyer Island Conservation Trust’s white shark biologist, Alison Towner, retrieved the shark and brought it back to DICT’s Kleinbaai facility. The necropsy took place on Monday the 27th.
The white shark is a juvenile 2.8 m female. Her head was removed on the Sunday morning post mortem but luckily the team at Infanta were able to retrieve it. The shark had no tag but she may be recognised by researchers using photographs of her dorsal fin and tail patterns.
“There are no obvious sign of Orca bites and she has her liver intact” said Towner. “The shark does have a fresh hook with steel trace lodged in her jaw and a gaff mark on the upper caudal lobe. We suspect, similar to the last Mossel Bay white shark mortality she likely fought with an angler resulting in her death.”
Special thanks to everyone that helped retrieve the shark, in particular, Altus De Witt, Attie Louw, Chris Louw, Oliver Von Hasseln, Katie Von Hasseln, Jakes Lord, Sarah Halse, Jack Hanekom, Mike Midgley Fraser Nxumalo & Daniel Lightley
NECROPSY
The shark necropsy began at 10am allowing scientists from Hermanus and Cape Town time to arrive. It was led by Alison Towner and Kelly Baker, white shark biologists from the Dyer Island Conservation Trust and Marine Dynamics.
Although the shark had a fishing hook and gaff mark to the tail, the gear size was considered too small to be targeting the shark directly. If it was the cause of death, it is difficult to confirm without evidence of the fight and fresh blood samples. White sharks can readily die from stress when hooked and fought, their hormone and electrolyte levels rise to lethal levels quickly as seen in Mossel bay back in May 2017. The female shark had remnants of a common dolphin inside her stomach, its skull and vertebrae. This fascinated the team of biologists which learn new information at each necropsy event. Her liver was clean and weighed nearly 30kg which is considered an indicator of good health.
“This is the seventh white shark retrieval/necropsy I have participated in this year” said Alison Towner. “We cannot keep losing white sharks at this rate in South Africa. Orcas made a huge impact this year, but longliners, poaching and careless fishing practice are also a very real threat to an already vulnerable and pressurised white shark population. Removal of white sharks effects the entire ecological composition along our coasts, which we are already beginning to see.”
A timeline of deceased Great White Sharks found around the Gansbaai and Struisbaai area, due to Orca predations can be found here and here
