Hearing of harbour seals under threat from wind turbines

Noise from the construction of offshore wind turbines could be damaging the hearing of harbour seals around the UK, researchers have found.

A grey seal Image by Dave_S / CC BY 2.0

A study by ecologists from the University of St Andrews found that around half the seals they analysed during a construction project in England were exposed to noise levels that exceeded hearing damage thresholds.

Overall, experts said, little is known about the impact of construction noise on sea mammals’ hearing and they have called for more research to be carried out into the issue.

Offshore wind turbines are installed using pile drivers – essentially large hammers that drive the foundation posts into the sea bed – which produce short pulsed sounds every few seconds.

According to the researchers, there are currently 1,184 offshore wind turbines around the coast of the UK, between them generating around 4GW of power. The next round of construction, which began last year, will see hundreds more turbines installed to generate a further 31GW.

Conducting their study, the St Andrews team attached GPS data loggers to 24 harbour seals while offshore wind turbines were being installed in the Wash in 2012. The data loggers collected information on the seals’ locations and their diving behaviour.

The researchers then combined this data with information from the wind farm developers on when pile driving was taking place to produce models which predicted the noise to which each seal was exposed.

The model revealed that half of the tagged seals were exposed to noise levels which exceeded hearing damage thresholds, the research team said.

The study is published today in the British Ecological Society’s Journal Of Applied Ecology.

(Press Association)