Whales die slow death from fishing gear entanglement

Scientists working out of the Woods Hole Oceanographic Institution have released data that shows ‘for the first time how fishing lines changed a whale’s diving and swimming behavior. The monitoring revealed how fishing gear hinders whales’ ability to eat and migrate, depletes their energy as they drag gear for months or years, and can result in a slow death.’

The study of a young North Atlantic Right Whale  called Eg 3911 involved suction cupping a device that was able to follow Eg 3911 under water. ‘The Dtag, developed at Woods Hole Oceanographic Institution (WHOI), recorded Eg 3911’s movements before, during, and after at-sea disentanglement operations. Immediately after Eg 3911 was disentangled from most of the fishing gear, she swam faster, dove twice as deep, and for longer periods.’

Unfortunately it appears that the early entanglement had proved too much for Eg 3911 and she was observed dead at sea in february 2011 and a necropsy showed that effects of the chronic entanglement were the cause of death.

Conservationists have known for some time that entanglements have a signifcant effect on the behaviour of whales and dolphins. WDC North Atlantic Right Whale Programme is campaigning to reduce the impact of fisheries and shipping on thgese highly endangered whales.

WDC has previously published on the deveasting impacts of fisheries on the welfare of dolphins and whales ‘Shrouded by the Sea‘.

Worldwide, it is estimated that more than 300,000 cetaceans (whales, dolphins and porpoises) die every year as a result of getting caught incidentally in fishing gear. These deaths are known
to be a problem in terms of conservation; placing unsustainable pressures on already vulnerable populations of animals. Some entire species such as the tiny vaquita, Maui’s dolphin and the
North Atlantic right whale are being pushed literally to the brink of extinction by fisheries bycatch.

What has not been recognised is the significance of this problem in terms of the welfare of each animal that suffers the fate of getting caught in fishing gear. Most victims die directly as a result of such interactions but the duration of this ordeal can vary considerably between species. Equally, the nature of the bycatch process varies with different types of fishing gear. Typically, however, animals suffer multiple injuries from the trauma of being caught or their efforts to escape, ranging from cuts and bruises to amputations and fractures. Some survive the capture but then endure protracted suffering from the injuries they sustain.

While the process of capture varies between different fishing gears, what is common is that, as intelligent, air-breathing mammals, once caught individuals go through a desperate struggle to escape, often incurring severe injuries, before most, that do not escape, probably die through asphyxiation.