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Whales are disturbed by noises made in trawling deep waters

 

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A sperm whale with her young calf; Irish researchers have found the noise from deep-water trawling can upset whales. Photo: AP Photo/Chris Bangs

A sperm whale with her young calf; Irish researchers have found the noise from deep-water trawling can upset whales. Photo: AP Photo/Chris Bangs

A sperm whale with her young calf; Irish researchers have found the noise from deep-water trawling can upset whales. Photo: AP Photo/Chris Bangs

Whales are known to be disturbed by the noise of ships as well as oil and gas drilling, but a new study says bottom trawling by fishing boats can also upset them.

Scientists at NUI Galway’s (NUIG) Ryan Institute have found the sound generated by trawling for fish around underwater canyons is amplified and may affect marine mammals’ ability to hunt and navigate.

The team used hydrophones to record the impact on the marine environment of trawlers in two surveys in the Irish and Celtic Seas.

Ecologically sensitive areas of the oceans need stronger environmental protection from the wide variety of potential pollution sources, including ships, deep-sea mining and bottom trawling, the team suggests.

The scientists modelled how the noise generated by bottom trawling could travel through the water column, along the seabed, and through a 20km-long submarine canyon in the Porcupine Basin off the south-west Irish coast.

They found the noise funnels through underwater canyons and into deeper waters, affecting marine mammals feeding and migrating.

They also discovered “modelled trawler sound” generated on the seabed travels underwater more “efficiently” than sound generated at the surface.

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Eoghan Daly, a PhD researcher with NUIG’s Irish Centre for Research in Applied Geosciences, said raised levels of marine noise can “interfere with a marine mammal’s ability to communicate, hunt and navigate using echolocation.

“Human-derived noise in the world’s oceans comes from many sources”, but bottom trawling’s impact has received “little attention to date”, he said.

“In an ocean already faced with plastic pollution and climate change, a better understanding of trawler noise pollution will highlight it as another human impact on the marine ecosystem,” Mr Daly said.

The team hopes their research will inform improved environmental regulations near key marine habitats and marine protected areas.


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