Fishermen say the mammals are teaching successive generations where to hunt, but so far they have not been able to stop them. Even firing small explosive charges has been useless. "It was like ringing a dinner gong," Tasmanian fisherman George Mure said. "It wasn't long before they learned 'bang' meant food."
Thanks to Hollywood, the largest member of the dolphin family is known to millions as a gentle giant. The species is actually an efficient hunter of other whales and seals, and is now turning in increasing numbers to fishing lines for food. Killer whales have made such a dent in the bluefin industry off Tasmania that the fishery is now on hold. "They adore tuna," Mr Mure said.
Others confirm the problem. Bob Lister, director of the Tasmanian Fishing Industry Council, said killer whales have learned to cruise a line many kilometres long. "We are finding the killer whales are actually moving along the line and taking the fish, and they seem to be taking their youngsters along and teaching them," he said.
The Australian Fisheries Management Authority claims killer whales have learnt to identify fishing boats, and follow them when they come to retrieve lines. "They seem to know the sound of each different vessel," the authority's fishery manager, Margot Sachse, said.
For Mr Mure, the situation is proving impossible. "They take the lot. All you get is bottom jaws with hooks through them. They pluck them like grapes." He has changed tactics to outwit the whales - instead of using droplines, which are retrieved vertically and slowly, he uses bottom longlines, which are hauled rapidly at a shallower angle. "They come in fairly fast, and so far that's a bit daunting for the killer whales."
Another possible solution is scaring the whales with underwater acoustics. Queensland Fisheries Service is working on a project to deter false killer whales and pilot whales, which are causing major economic losses from tuna fisheries in the north.
Ms Sachse said the killer whale problem is coming to a head, with industry leaders set to meet a New Zealand maker of the scaring devices this week.
