TRANSMITTERS attached to the backs of albatrosses have pinpointed the places where the great birds go fishing – and found that they choose the same spots as rogue fishing fleets hunting for tuna and other valuable fish.
This is bad news for a bird that appears on the World Conservation Union’s threatened species list, because albatrosses that tangle with a fishing boat’s lines are invariably drowned.
John Croxall and Peter Prince of the British Antarctic Survey in Cambridge have been collecting data from the tagged birds for months. Their report, presented at the BA in Newcastle upon Tyne this week, suggests that there is an urgent need for stricter controls on long-line fishing off the Patagonian shelf in the southwest Atlantic.
In long-line fishing, each boat tows a main wire trailing hundreds of lines with bait attached to them. The lines sink into deeper water where tuna, hake and the much sought after Patagonian toothfish swim. But albatrosses and other seabirds often dive after the bait before it sinks. Once hooked, they cannot escape and sink with the heavy line.
Croxall and Prince fixed transmitters to the backs of 30 or so wandering albatrosses. The transmitters send signals via satellite to Toulouse in France, and from there electronically to Cambridge, 10 times a day, so the researchers can tell where the birds are, how fast they are flying and whether they are in the water. Some birds have been fitted with sensors that monitor heart rate and temperature, which indicates when the birds are feeding.
Croxall has found that the albatrosses share feeding “hotspots” off Argentina with southern elephant seals. The hotspots lie in a tongue of colder water rich in nutrients and fish. Unfortunately for the albatrosses, it is also rich in the sorts of fish sought by vast, unregulated fishing fleets, mainly from Korea and Taiwan.
“This is the first demonstration of the magnitude of overlap between the unregulated long-line fisheries and the foraging areas of the albatrosses,” says Croxall. “If you wanted to stop albatrosses from dying, this would be a very good place to focus.”
Fleets could adopt techniques that pose less of a risk to the birds, says Croxall. These include adding weights to the lines so they sink faster, or fishing only at night when the albatrosses are not foraging. Norwegian fishing fleets are pioneering techniques for spreading the lines from beneath boats so the birds cannot see the bait.
“The challenge is to get proper management of unregulated long-line fisheries in the southwest Atlantic,” says Croxall. Otherwise, the decline could continue. In South Georgia alone, he says, the number of breeding birds has fallen by 30 per cent over the past three decades.