Cape Town Raggies released at Granny’s Pool
One of the four juvenile ragged-tooth sharks that have been released by a team from the Two Oceans Aquarium at Granny’s Pool last week was found dead at Bruce’s. Although an autopsy has been done, the cause of death is still not sure.
Dusty Elton, who witnessed the release of the four sharks last week, found the shark at Bruce’s early on Tuesday morning (19 June) and alerted Rob and Sam Bester from GypSEA Marine Eco Tours. ”We noticed stitches on the shark’s belly and realised that it must have been one of the Two Ocean’s tagged sharks. The tag on its back was removed which made us think that the shark was caught by a fisherman and left on the rocks to die,” says Sam. “However, an autopsy didn’t find any evidence of the shark being caught.”
Vemco transmitters were surgically inserted by Dr Malcolm Smale, shark scientist at the PE Museum last week before they left Cape Town. The tranmitters are worth R10 000.
Dr Smale is doing an acoustic telemetry research project on Ragged Tooth Sharks and came to St Francis to do a full autopsy. They are still awaiting the final results.
The fact that the shark was found, means that the other three might still be in the vicinity of St Francis. Ragged Tooth Sharks can only eat what they can bite and swallow at the same time, so are harmless to humans.
The sharks have been released at the Granny’s pool after spending a few years at the Two Oceans Aquarium in Cape Town. The truck and crew drove from Cape Town through the night and immediately released the sharks on arrival.
The whole process was documented by Rob and Sam, who also kept an eye on the ocean for a few hours. Normally the releases take place at Buffels Bay (close to the Knysna/Plettenberg Bay area), but due to current water temperatures, the team has decided to release them in St Francis. They will find other ragged-tooth sharks of a similar age in the vicinity.
The ragged-tooth sharks in the Two Oceans Aquarium were collected on rod and line in a little bay aptly named “Little Raggie Bay” in a private resort called Mgwalana, approximately 60km south of East London. Roy Martin, the official ‘’tagger’’ for Bayworld in Port Elizabeth, assisted the staff in collecting these sharks.
Little Raggie Bay is a very shallow bay and is one of a number of similar-sized bays on this part of the coast, which young ragged-tooth sharks use as “nursery areas”.
The juvenile ragged-tooth sharks act as ambassadors for their species and are only displayed for a short period of time at the aquarium before they are returned to the wild. Ragged-tooth sharks are found on the southern and eastern coasts of South Africa. In November/December they congregate to mate on reefs in northern Eastern Cape and southern KwaZulu-Natal waters. The pregnant females then travel north as far as southern Mozambique to gestate in warmer waters. After a gestation period of 9 to 12 months, they return to the Eastern Cape (south of the Kei River) to give birth.
Using satellite and ultrasonic tags, scientists have been able to gain more detailed information about the movement of ragged-tooth sharks up and down the South African coast.
Ragged-tooth sharks are threatened around the world because they are slow to reach sexual maturity, they give birth to few young and, because of their inshore habits, they are highly vulnerable to over-fishing.
The status of the South African ragged-tooth shark population was considered to be “near threatened” by an International Union for Conservation of Nature working group in 2003. However, the actual size of the population is unknown and is currently under investigation.
Information: Two Oceans Aquarium, South Africa.