Friday 20 September 2019

Whales getting stranded when 'fleeing noise'

Humpback Whales off the coast of Ireland. Credit: Eire Fhiain / TG4
Humpback Whales off the coast of Ireland. Credit: Eire Fhiain / TG4

John von Radowitz

Whale strandings could partly be caused by the animals becoming exhausted while trying to escape from human noise, scientists believe.

A study has found that startled beaked whales swimming away from low frequency sonar boost their energy consumption by more than 30pc.

Tests on trained dolphins showed that they doubled their energy use when pushing against a force plate in a pool.

Cetaceans such as dolphins and whales, which have to surface to breathe, balance their energy demands against a limited supply of oxygen.

In some cases fleeing whales may run out of steam and become washed up on beaches, the research suggests.

US lead scientist Dr Terrie Williams, from the University of California at Santa Cruz, said the study showed a big difference in the energy cost of whales swimming normally and attempting to escape danger.

"In view of the number of cetacean mass strandings across the globe and the increase in human presence in the oceans, such data are critical," she said.

The research involved training six bottlenose dolphins to take part in swimming tests while scientists measured their oxygen consumption and the rate at which they beat their fins.

More than 50 dolphins and whales have washed up on beaches in Ireland so far this year. It makes 2017 the worst on record for strandings.

And meanwhile, experts are still at a loss to explain the mass stranding of more than 600 pilot whales that washed ashore on New Zealand's South Island over the course of two days last month.

Irish Independent

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