250709 Trouble in the deep Changes in the number of shark species being caught in Sharks Board nets could be an indication that these creatures of the deep are under threat, writes Matthew Savides IT’S a purely illustrative figure, but an alarming one nonetheless: 100 million sharks are pulled out of the world’s oceans each year. And, according to KZN Sharks Board scientist Geremy Cliff, it could be even higher as this figure has been quoted unchanged for a number of years. This has put shark populations worldwide under huge pressure, and it is starting to show in some species caught in shark nets and on drumlines across the KwaZulu-Natal coast. But the local catches are a tiny portion of the whole. Cliff and Dr Sheldon Dudley, also of the Sharks Board, pointed out that only 600 sharks are caught in the shark nets or on drumlines in KZN annually – a tiny 0.0006 percent of the global total. The Sharks Board does, however, pay close attention |to the local impacts of its |activities. Hence, measures put in place by the Sharks Board have resulted in their annual |shark catch coming down by half, from 1 200 a year in the latter part of the 1990s to the current 600. And they are actively putting measures in place to reduce the impact on other groups of animals. One of these measures is the use of drumlines – effectively a series of baited hooks – in place of some of the nets at beaches on the Hibiscus Coast. This has reduced the catch of other marine life, including dolphins, rays and turtles, by 50 percent at those beaches. Reduction The nets have brought about a reduction in numbers of sharks at the protected beaches, however, and this is a good thing for swimmers |and surfers. Yet these reductions have not prevented the development of a thriving shark diving industry, particularly on the KZN South Coast at Aliwal Shoal. Dudley and Cliff were both adamant the shark nets and drumlines were not the chief reasons for an apparent decline in local populations of certain shark species, but that factors from other parts of the western Indian Ocean, particularly commercial fishing, were more to blame. Dudley was involved in a study of 14 shark species |commonly found in KwaZulu-Natal and that often got |caught in the shark nets over a 23-year period. Of the 14, nine showed no change in the population size, as indicated by catch rates |in the shark nets, only four showed a decrease and one, |the tiger shark, showed an increase. The research was limited to catch rates of sharks caught |in the nets, meaning that sharks occurring further offshore or smaller species were not included. “We don’t have data from locations between the net installations or off-shore of the nets,” Dudley said. This means that while the nets might have reduced populations at the protected beaches, it does not necessarily mean the populations are down in other parts of the coast. One of the species showing a decline is the Zambezi – or bull – shark. Zambezi sharks are believed to have been responsible for many of the shark attacks on the KwaZulu-Natal coast in the years before protective measures were introduced. Dudley said his research showed the population had “decreased markedly” at the net-protected beaches. “We believe the nets have had an effect on the numbers |at the protected beaches. It appears the nets have largely removed them from those beaches,” he said. However, this does not necessarily mean the species was being wiped out. Data has shown that Zambezi sharks are not highly migratory, so the numbers being caught in the nets are likely primarily to be those associated with the area itself. This means the populations elsewhere are not likely to be greatly affected by the catches in the nets. Dudley added that there are no nets north of Richards Bay, which makes it difficult to establish how the populations are being affected in other areas. This shark has a tropical and subtropical distribution and its range in East African waters probably extends as far north as Somalia. Zambezi sharks are also found on reefs offshore of the nets, and at locations on the South African coast to the south of KZN. “There are certainly Zambezi sharks around, but the shark nets are just not sampling their numbers in other areas,” he said. What is most worrying to Cliff and Dudley is the sharp decline in the populations of two species of hammerhead shark. The catches of great hammerhead have decreased by 79 percent and the scalloped hammerhead by 64 percent. However, this steep decline is not likely because of the nets but because of targeted fishing in other parts of the western Indian Ocean. For example, during the study period only 10 great hammerhead sharks were caught each year in the nets, which is not a large enough catch to have had an effect at the population level. The fins of these sharks are used in shark-fin soup, which is both a delicacy and status symbol in parts of the East, particularly China and Taiwan. Therefore there is a huge financial incentive for commercial fishers to catch the sharks as the fins can fetch as much as R90 000 per kilogram in China, according to a recent article in the UK-based The Times newspaper. Targeted Essentially, because the shark is being targeted elsewhere, and because it commonly migrates between the western parts of the Indian Ocean, it was not reaching the KZN coast in as large numbers as it was before. “The great hammerhead has shown the greatest decline (in population). The declining catch rates in our nets are showing the populations are taking a huge knock. This has set alarm bells ringing,” Dudley said. Another species showing a decline is the blacktip shark, which Sharks Board officials said was unexpected because this species is relatively fast-breeding and, therefore, one of those better able to sustain fishing pressure. Dudley said the decline might be because one of its main nurseries in southern Africa is believed to be in Mozambique, where there have been reports of fisheries operating where newborns are caught. The industry is also not as well regulated there as in South Africa or other parts of the world. Asked if it was likely the population was decreasing dangerously, Dudley said: “Probably not, but the numbers have declined and we have the warning signs.” He also pointed out that this is a species encountered regularly in waters some distance offshore of the shark nets by both divers and fishermen operating from skiboats and hence the declining catch rates evident in the shark nets may not reflect a general decline in the population. The one shark showing an increase in population size is the tiger shark, following the same trend as the Australian states of Queensland and New South Wales. “It is possible that the tiger shark, which is a more productive species than others caught in the beach protection programmes, enjoys a competitive advantage. This may be enhanced by the relatively high rate of release of live animals of this species,” Dudley said. While tiger sharks “have been implicated in shark attacks on bathers and surfers in various parts of the world, including KZN”, he said there was no evidence of such incidents increasing at protected beaches in KZN. What these figures mean on a larger scale is that the Sharks Board can alert international authorities and relevant groups about the trends here and what these may mean for wider shark populations. Using this information, the groups can push for tougher legislation to ensure shark numbers are not dangerously diminished. In the meantime, though, the Sharks Board remains committed to fulfilling the first of their two government-determined mandates: to reduce the number of shark attacks and keep swimmers safe. At the same time they are always pushing to find new ways to limit

Melanie Gosling

and Lauren Isaacs

THE city council has received several e-mails suggesting changes to the colours of shark-warning flags, but has said the flags will stay as they are.

In the aftermath of the shark attack last week, some have called for a simple green, orange and red system of flags.

However, Gregg Oelofse, head of the city’s environmental policy and management department, said yesterday this would conflict with the international standard.

“I’ve had about 30 e-mails suggesting every colour from blue to yellow to striped. The international life-saving standard to indicate a shark is in the water is a white flag with a black shark on it. It is not our choice, and there might have been better choices, but is an international standard.

“Some people say it would be better if we flew a red flag, but the life-saving clubs say this will create confusion.

“The white flag is used all over the world,” Oelofse said.

In a snap survey of 10 people on Fish Hoek beach yesterday, four knew what the shark flags meant, and six did not.

Oelofse said all beaches were well signposted and it was easy for beachgoers to acquaint themselves with the flags.

“A lot of people do know what they mean, and if we start changing the flag colours now, it will lead to a lot of confusion. Green is for go and speaks for itself. The black flag means the spotters can’t see well, that visibility is poor. The red indicates a high risk, either because a shark has been spotted recently, or because there is a likelihood of a lot of shark activity. And when the spotters do see a shark, we put up a white flag, which is what they do all over the world.

“Internationally, they don’t have the other three coloured flags as we do, because other countries don’t have shark spotters,” Oelofse said.

All 10 people interviewed knew that the siren meant a shark had been seen and everyone should leave the water. However, some said the siren was not audible on the Clovelly side of the beach.

All those interviewed said it was good that the flags carried an image of a shark. All said they would prefer a system of only two flags, showing whether one could or could not swim. Most knew that Fish Hoek was a high-risk area.

Mike Steptoe, a Briton who lives both in Fish Hoek and London, said when his friends from the UK telephoned him, many of them asked if there had been any shark attacks at Fish Hoek recently.

“People all around the world know that Fish Hoek is great white territory,” said Steptoe, who believed the current system of shark warning flags worked well.

Alistair Horton, formerly captain of the New Balance Fish Hoek Life Saving Surf Club, suggested that an extra 50c could be added on to the R8 parking fee at Fish Hoek and the money used to print flyers, with explanations of the flags, to be handed to the public.

Oelofse said yesterday no beaches were closed, but the shark spotters were on high alert because of the increased shark activity on several False Bay beaches. Red flags were flying at Muizenberg, Kalk Bay, St James, Glencairn and Fish Hoek, indicating either that sharks had been seen recently, or that there was an increased risk that sharks would be in these areas.

“It is really not unusual for sharks to be present at this time of the year, as we have said. It is completely normal, and the spotters are on top of it as best they can be,” he said.

l Michael Cohen, who lost a leg when he was attacked by a great white at Clovelly on Wednesday, is still in the intensive care unit at Constantiaberg hospital, where his condition is stable. On Friday, he underwent a second operation on his foot, which had been almost severed by the shark.

See www.sharkspotters. org.za for more information.