Another Life: Undersea noise caused by humans a major threat to whales and dolphins

He would have met dolphins aplenty, arching ahead of his yacht beyond Dingle Bay. The sight of a whale was perhaps more rare: a distant spout or occasional, glistening fin.

Today, Charles Haughey’s feeling for nature – unique in past Irish governments – can claim an expanding legacy in conservation. Just 30 years from his declaration of Irish waters as a cetacean sanctuary, a Cork university academic leads Europe’s campaign against a major threat to whales and dolphins and much else in marine life: human-caused, undersea noise.

At UCC's marine research centre, MaREI, Dr Gerald Sutton already co-ordinates Jonas, a partnership of EU Atlantic scientists aimed at existing noise impacts.

Now he leads Saturn, a project launched this year and aimed at the noise from shipping. A €9 million project with multiple EU partners, it finds the ocean unusually quiet as Covid cuts sea traffic and keeps cruise liners at anchor.

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This fortuitous pause offers “a good time for listening”, as one researcher puts it, and further assessment of damage to marine life. A recent world review in Science found “massive declines in the abundance of sound-producing animals” and impacts extending to fish and seabed creatures, seabirds and reptiles.

In western Europe, it was recently dramatised by the stranding of beaked whales on Irish and Scottish coasts, notably of 15 Cuvier’s whales in 2015. Studies of mass strandings of this deep-diving group have implicated military exercises at sea, using anti-submarine sonar.

In February, the Royal Society in Britain published the latest "co-occurrence of beaked whale strandings and naval sonar" from islands in the west Pacific. This painstaking study found "highly significant" links between the two.

Naval active sonar is linked to exceptional cetacean strandings in sources of ocean noise explored by Jonas, the research project co-ordinated from UCC. As they attempt to flee the sound, it says, the stressed animals may alter their diving pattern, triggering physiological changes that lead to stranding.

More shocks come from oil/gas exploration. Seismic air guns are especially damaging, given the ocean’s capacity for transmitting sound. Their “potentially deafening blasts” have been detected as far as 4,000km, a similar range to some whalesong communication. The “impulsive” noises from construction, such as pile-driving for offshore wind turbines, can be heard by harbour porpoises up to 80 km away.

Noise from countless ship propellers and machinery is, however, says Jonas, “the primary source of ambient anthropogenic noise in the ocean”. Travelling hundreds of kilometres, it can reach great depths and distances without much loss of intensity.

Cutting vessel speeds can have a big effect. A study for Seas at Risk found that slowing ships by around a fifth yielded twice the reduction in sound energy. Ships can also be made quieter. Saturn, the new project led from UCC, has participants from 10 countries in a project to create and test engineering and other solutions.

New designs for ship propellers and hulls will bring cost-effectiveness to the “noise signatures” of individual ships and particular sounds will be measured for their impacts on ocean life.

UCC also has the benefit of research by other Irish universities. Last December, for example, NUI Galway published work showing that bottom trawling in or near underwater canyons off Ireland can bring disturbing noise to important feeding grounds of fin and beaked whales.

Trawling noise

Led by PhD student Eoghan Daly aboard the Marine Institute's research vessel Celtic Voyager, a team found trawling noise travelling along the seabed and through a 20km-long submarine canyon in the Porcupine Canyon.

Such disturbance continues while other sources change in intensity. The sonar bangs of oil-gas searches have greatly diminished as Ireland ends further offshore exploration. But multi-beam sonar is still the tool of seabed mapping, and the Infomar surveys of the Geological Service continue this year, both inshore and offshore, using the Celtic Voyager.

In the Irish Sea, construction of big new offshore wind-farms will take pile-driving to a thudding new peak. And the prospect of further, floating wind farms off the south and west adds to the concerns of the Irish Whale and Dolphin Group, science-based guardian of Ireland’s 24 cetacean species.

In a generally supportive policy on offshore windfarm development, it calls for international precautions, including “soft start” of noise levels to scare cetaceans away. It’s apprehensive that the chains anchoring floating turbines will trap drifting nets and entangling lines. And as future turbines grow bigger and louder, their continuing noise should have a decibel limit that cetaceans are happy with.

With co-founder Simon Berrow as its chief science officer, the IWDG will continue to sail after Ireland's humpback whales, with Celtic Mist as its research vessel. The yacht was a gift from the Haughey family and serves as a rare Irish political initiative for the good of the natural world.