Jaws: Killer sharks 'showing intelligence'

The sharks feeding off KwaZulu-Natal have shown remarkable intelligence, learning to evade the shark nets and to follow the ski-boats to get food, resulting in a concentration in certain areas.

There has been a spate of close shark encounters during the past few weeks. Since New Year's day, two men have been victims of shark attacks, a surfski was chomped and fishermen have lost parts of their catches to sharks in various areas along the coast. From Mtunzini to Umdloti to Durban harbour, sharks thought to be of the Zambezi or Tiger family have been making themselves known.

Natal Sharks Board biologist Dr Sheldon Dudley said there was no true explanation or link between the sightings.

"They are just random. All three areas are known to have shark activity. In most cases, the fishermen or surf-skiers were out in the hours of darkness, the shark's main feeding time. In some cases, they were on the edge of deep channels, allowing the sharks to gain momentum before attacking in shallow water."

He added that while there were signs of increased shark activity, the number of sharks being caught in the nets had decreased drastically. "In some areas like Umdloti, if you took the number of sharks in the area by the number caught in the nets, you would say there was little to no activity there," said Dudley.

"But a few kilometres away from the netted beach is what is called the Umdloti drop-off. It is like a wall that goes down about 28m, then drops to 34m. It is a good fishing area and attracts a large number of sharks. We have had numerous reports of sharks taking a fisherman's catch off his line in this area," he added.

Kit Case has been ski-boat fishing in the Umhlanga/Umdloti area for more than 35 years. "There is a lot of small fish in this area, which attracts game fish and, naturally, the sharks go for the game fish, but it has always been like that."

The sharks hover under the ski-boats and when a fisherman takes a catch, they go for it. "Yes, there is a shark problem. They take the fish off your line. Some days, every fish you catch is taken, the very next day you may only lose one."

But Case believes the sharks are showing signs of intelligence. "They know to follow the ski-boats. They hear or feel the vibrations and then wait for the fishermen to take a catch," said Case.

He said a few weeks ago he hooked a large barracuda, which was taken by a shark. He hooked three more smaller fish which he got into his boat. Then he hooked another big barracuda which again was taken by a shark.

"I fought and got the trace out of his mouth, but noticed my other trace was still in his jaw. This was the same shark that attacked my catch five kilometres and a good couple of hours previously. It had followed my boat," he added.

The sharks were congregating around the fishing boats and unless surf and paddle skiers were trying to pull in fish, they should be safe, he said.

"The sharks are going after the fish, not the person. A guy can sit dangling his legs over his surf-ski all day and I doubt he will be attacked, but as soon as he starts to fish, the sharks will come."

Dudley said the sharks board's main mandate was to protect the surfers and swimmers at protected beaches. Durban was still the safest area countrywide. Surf or paddleskiing, spear-fishing and fishing at night, early morning or dusk was just asking for trouble.

"We appeal to the public not to panic. These shark incidents have occurred in unprotected waters and in aggravating circumstances," said Dudley.