On Thursday 11 April, the Two Oceans Aquarium successfully completed its project to safely return two ragged-tooth sharks to the wild.
Kay, a female ragged-tooth shark, has been resident at the Two Oceans Aquarium since 2009. She had been collected in East London for display at the Aquarium, and is named after the wife of a local fishing guide there, who assisted the team in collecting her. She was joined by a young male ragged-tooth shark, who had been resident at the National Zoological Gardens of South Africa in Pretoria, for the release.
The team had removed Kay safely from the I&J Predator Exhibit earlier in the week, and placed her in a holding tank, along with the young male (read Farewell to Kay – Part One here). The two were then tagged with VEMCO internal acoustic tags – after anaesthetising the sharks, the vet made a short incision (3cm to 5cm) in each shark’s belly, inserted the tags into the abdominal cavity, and stitched up the cut. The tags are made of a biologically inert material, meaning they will not harm the shark in any way, and they will stay inside the sharks’ bodies for the rest of their lives.
On Thursday morning, the two sharks were carefully moved into a transportation tank on the back of a large truck, and driven off to Gordon’s Bay harbour, where the team readied them for release.
Their vital signs were then checked, as well as their new tags. Thanks goes to Lwandle Technologies, which lent us a VR100 (a very expensive piece of equipment). The VR100 picks up the acoustic pings that are transmitted by the VEMCO tags. These same pings are picked up by base receiver stations, which are positioned along the South African coast.
With everything in order, the sharks were sedated, carefully positioned in a stretcher, and moved by crane from the back of the truck on to Aquarium 1 – our custom-designed boat built for transporting animals to and from the ocean.
Travelling a short distance out to sea (roughly two nautical miles), Aquarium 1 and the flotilla of other boats carrying Aquarium staff and members of the media came to a stop to release the first shark – the young male. After gently lowering the stretcher into the water, the Aquarium’s team of divers made sure the shark got off safely – and were happy to see him disappear off into the blue.
The team then returned to the harbour for the second release. This was Kay’s turn! A few quiet goodbyes were whispered to her from the Aquarium’s curatorial team, who have fed and looked after her for the last four years. Once in the water, she soon swam off to explore her new home – the open ocean.
Everything went swimmingly.
Thanks to everybody who helped out on the day, and for those who have been following and sharing this story online! We wish that more people out there cared about these magnificent ocean creatures.
Changing shark perceptions
Sadly, sharks are among the most maligned creatures on our planet, thanks largely to the movie Jaws, which sensationalised and portrayed as them as people-eating monsters.
If sharks are to survive globally, they require support from organisations and individuals who are in a position to change people’s perceptions of them. Our task as a public aquarium and a marine conservation organisation is to inform people of the role of sharks in the oceans and the importance of the larger species as apex predators. This is why we believe that it is important that people get to see living sharks in our Aquarium and to learn as much about them as they possibly can.
The sharks that we display in the Aquarium only spend a few years with us before returning to the ocean. We see them as ambassadors – teaching us about their species and hopefully inspiring a sense of awe and appreciation in our visitors. Some 52 000 schoolchildren visit us every year – hopefully we are educating future generations and slowly erasing the Jaws mentality!
The stresses of moving home
On release days, our curatorial team takes great care to make sure the sharks experience as little stress as possible – they are lightly sedated and handled as very precious cargo. It is a great day for us when we release these animals back into the wild and see them swim off into the ocean. But we also experience some anxiety about their future, and hope that they will not fall prey to uncaring humans who see them as vermin or catch them for their fins.
The release is also an opportunity for people to see the sharks and for us to share information about them. It is amazing to see how many people come to watch, as well as their responses – most show real concern about the sharks and their well-being, which is exactly the attitude that we are trying to instil.
Plotting her next move
The acoustic tags Kay and the young male now carry transmit a signature signal that is logged each time the animal passes by a specialised “listening” station. There are an array of these stations along the South African coastline. This means that we should get near-shore migration data on each shark for the next 10 years, helping scientists to track their movements, leading to a better understanding of ragged-tooth shark migration, behaviour and population dynamics.