THE biggest baddest pair from Bayworld’s de-commissioned aquarium, two bulky raggedtooth sharks, were released yesterday (July 26 2011) back into the sea. It was a sad day for the oceanarium, where they have lived for nearly two decades, inspiring awe in hundreds of thousands of visitors – but it is good news for the species, as the pair are now part of a research project aimed at securing our waters as one of the few safe havens in the world for raggies.
Besides a dozen penguins which may be retained for a permanent education exhibit, the sharks are the last animals that must be relocated from the oceanarium to allow work to begin on its “re-imaging and rebuilding phase”.
The two sharks were caught 19 years ago off the north side of the harbour wall at Good Sheds, and they were released at the same spot (now occupied by the Knysna Oyster Company) after being transported through Port Elizabeth’s streets in oxygenated crates, on the bank of a flat bed truck.
The operation was co-ordinated by senior SA oceanarium specialist Dr Tony McEwan, who was involved in the construction of Cape Town’s Two Oceans and a similar enterprise in Kuwait, as well as the transfer of Bayworld’s dolphins to Hong Kong and the 2006 grand plan for the rejuvenation of the Bayworld oceanarium, before it was shelved because of funding problems.
The first step yesterday was to open the plug in the holding tank which the sharks have been sharing with one small remora suckerfish which has been a life-long companion of the female raggie.
Three quarters of the water was released and at the same time oxygen was pumped in to ensure the animals could continue breathing comfortably.
Anaesthetic was emptied into this remaining water and, after 15 minutes, it had been taken in through the sharks’ gills and they were sluggish enough to allow McEwan and his team, including Bayworld shark specialists Malcolm Smale and Matt Dicken and aquarium curator Steve Warren, to clamber into the tank with them.
Using a canvas partition, they separated the animals and manoeuvered the smaller (120kg 2,45m) male onto a stretcher. Then Smale stepped in to physically turn the shark (which was still twisting around) onto its back.
Typical of a shark, as McEwan explained, as soon as this happened, it quietened down completely, and Smale was able to get to work, using a knife to slit open a small aperture in its belly and sliding in a cylindrical acoustic tag, thick as a man’s forefinger and about 5cm long. He squirted in some antiseptic and sewed the hole closed.
The tag will transmit signals to an array of listening stations that have already been installed along the local coastline, and Smale and Dicken will be able to download this data and thereby track the animal’s movements.
Then it was a matter of turning the shark back onto its tummy and inserting a different physical tag. The idea of this tag is that if it is hooked by anglers, they will be able to report the tag number and their position to the Bayworld team, before releasing it, Dicken explained.
One of the reasons raggies are so threatened is that they produce just two pups a year every other year. They are listed as critically endangered in several parts of the world and are considered regionally extinct from the Mediterranean where they used to occur.
In SA waters, they move between northern KwaZulu-Natal and the Eastern Cape, where they pup in Spring. Rresearch has shown that the biggest threat is from commercial ski boat anglers. Recreational anglers also pose a threat because, although they often release their raggies after they have reeled them in, these sharks often die anyway because of stress.
, Dicken explained.
Despite these and other threats, the future is bright in SA for the raggy. Over the last 20 years the population trend has been “stable-increasing and there are now an estimated 20000 in our waters, he said.
“The future is looking bright for the raggedtooth shark in South Africa.... This is possibly the last place left in the world where there remains a healthy and stable population. Continued research and reduced fishing pressures should help to ensure that our raggies do not decline to the extent that are evident elsewhere in the world.”
Ready then to take part in this vital continued research, with their tags firmly in place, Bayworld’s raggies were hoisted off the truck by a crane – supplied free by Knysna Oyster Company – and lowered into the cold sea.
Warren, who probably knew the animals better than anyone else, said he was satisfied they would be able to hunt for themselves because although they were fed in the oceanarium, they often snaffled some of their fellow residents to supplement their diet.
He and McEwan jumped in with snorkles and goggles to help tip the crates as they hit the water. The sharks slid away in an instant, leaving the two men treading water, and the rest of the release team on the pier in the rain and the way free for Bayworld to reinvent itself.