Life - First evidence that shipping noise stresses whales

Getting fed up with their noisy neighbours (Image: KeystoneUSA-ZUMA/Rex Features)

Even whales find noisy neighbours stressful – and they show it in their faeces.

The oceans have become much noisier over the last century because of shipping. We know whales can cope with the din to some extent by calling more loudly, but we have no idea if they are stressed by noise.

Rosalind Rolland of the New England Aquarium in Boston, Massachusetts, and colleagues used faeces to monitor the levels of stress hormones in endangered North Atlantic right whales (Eubalaena glacialis).

For two days after the 9/11 terrorist attacks, shipping traffic ground to a halt in the Bay of Fundy, Canada, and underwater noise fell by 6 decibels. During that time, stress-hormone levels in whales there were lower than in readings taken during September in the following four years.

We don't know how much stress hormone is normal for right whales, so we can't say at what level they are genuinely stressed, cautions Patrick Miller of the University of St Andrews, UK. But if these whales are suffering chronic stress, it could explain why they struggle to breed.

Journal reference: Proceedings of the Royal Society B, DOI: 10.1098/rspb.2011.2429

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