Seals are taking advantage of offshore wind farms to forage for food, satellite tracking has shown.

Data from tagging harbour and grey seals on the British and Dutch coasts of the North Sea revealed that 11 harbour seals visited two active wind farms off the German and UK coasts.

At both sites, the GPS tracking showed several worked their way through the area in a grid-like pattern and appeared to focus their hunt for prey on certain areas.

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Seals also tracked the path of sub-sea pipelines, with two seals in the Netherlands encountering a section of pipeline and following it on multiple trips for days at a time, the research published in the journal Current Biology showed.

In the north east Netherlands, four out of 96 seals visited Alpha Ventus, a wind farm off the coast of Germany, while seven out of 22 seals tagged in south east England went into the Sheringham Shoal wind farm.

Man-made structures in the sea create "artificial reefs" which lead to localised increases in the number of fish and crustaceans.

But it is not clear if the presence of the turbines actually increases the amount of prey available to seals, or simply concentrates them in a new location.

Deborah Russell, of the University of St Andrews, said: "I was shocked when I first saw the stunning grid pattern of a seal track around Sheringham Shoal.

"You could see that the individual appeared to travel in straight lines between turbines, as if he was checking them out for potential prey and then stopping to forage at certain ones."

She added: "Only a small proportion of our study seals utilised wind farms or pipelines. At present these structures cover a small proportion of the extent of the at-sea distribution of seals.

"As wind farms become more extensive, many more seals will likely be affected."