- A new study has shown that whales produce more stress hormones in periods of intense shipping. The findings came almost accidentally from one academic who collated data on underwater noise levels, shipping traffic, and faecal concentrations of the stress hormones (glucocorticoid) metabolites.
- Shipping levels around New York reduced substantially in 2001 following terrorist attacks, leading to a 6 decibel reduction in underwater noise, and significantly lower levels of glucocorticoid in whale faeces. The effect of the elevated stress in “noisy” environments is currently unknown. There are increased incidences of whales being hit by ships or tangled in nets, although a causal link cannot be currently suggested.
- This study has potentially major implications for marine renewable energy. It is possible that noise generated during the installation of wind, wave, or tidal machines, could induce stress in whales and other marine life. In particular, tidal machines are likely to cause higher noise levels throughout their operational life.
- More research is needed to understand how this finding may affect marine renewables, particularly as licencing agreements for renewable devices are often irreversible for 25 years post-licencing, regardless of evidence of environmental stress.
- Linking studies of stress hormone concentrations to behavioural studies would be a useful first step in understanding the real implications of elevated stress on marine life. In addition, it would be important to identify “tipping points” in noise levels for stress elevation, and compare this with likely noise levels induced by tidal and other renewable devices.
Other research under NERCs RESPONSE project will investigate the effect of tidal machine noise on seal behaviour.
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