Marine noise 'worth inquiry'

Loud underwater sounds could be interfering with whales' communication, say scientists. Photo / Northern Advocate

The possible connection between undersea noise and mass whale strandings in New Zealand deserves more attention, say marine scientists.

The stranding in the Far North of 70 pilot whales last month accentuated New Zealand's position as one of the most frequent sites of mass strandings in the world.

Scientists are keen to unlock the mysteries of group strandings, saying that our marine biodiversity and industry - especially tourism - is dependent on understanding marine mammals' behaviour.

Whales may become beached for various reasons - illness, disorientation or an unwillingness to abandon sick pod members. But the cause of mass strandings in New Zealand remains difficult to understand because of a lack of research and funding.

Te Papa marine mammals collections manager Anton van Helden said the effect of noise - sonar, seismic testing, or boating activity - on marine mammals was an obvious avenue for research.

Overseas studies had already made significant developments in this area. United States-initiated research in the Canary Islands and the Bahamas directly linked US naval activity, especially sonar, to mass strandings of beaked whales.

Similar research in New Zealand could be prohibitively expensive. Mr van Helden said acoustic testing for petroleum drilling would probably have to be funded by oil companies.

But scientists said New Zealand could begin making small steps to make sure mass strandings were not being caused by loud underwater sounds.

Marine biologist Dr Rochelle Constantine emphasised that New Zealand was unlikely to ever have resources to understand the physics of underwater sounds and their effect on marine mammals' behaviour.

"But, in saying that, it doesn't mean New Zealand shouldn't make a better effort at understanding the marine mammals in a particular area ... where seismic testing is being done."

She said the Government needed to keep good records of where loud underwater sounds were occurring.

"Because in the case of a mass stranding event, [the underwater sound] may well explain it. If we know when those sounds are occurring, we can respond to the strandings properly."

The Department of Conservation was reviewing its guidelines for seismic activity in New Zealand waters.

Operators such as petroleum prospectors were required to observe and listen for marine mammals when carrying out underwater work.

But Dr Constantine said, "I do worry that industry is getting away with a very basic level of monitoring, especially given the massive diversity of cetaceans that we have."

Her current research focused on the interaction between recreational boating and Bryde's whales in the Hauraki Gulf.

She said there was evidence that underwater sounds from boating could mask communication between marine mammals.