Offshore wind farms may be seal feeding grounds

harbor seal

Scientists tagged harbor seals in the North Sea with GPS trackers and found that a few of them regularly hunted at the base of wind turbines.

D.J.F. Russell et al/Current Biology 2014

In the search for cleaner forms of energy, many communities and nations have turned to wind. While wind can be intermittent in strength, it can be harnessed easily for renewable, carbon-free energy. But this form of energy has proven to be not entirely environmentally friendly. Bird and bat deaths are common. And some people have complained about the noise generated by wind farms. Others have argued against them on a purely aesthetic level.

That last reason has been one of the arguments that has prevented the development of offshore wind farms in the United States. But the story has been different in Europe and Asia, where many wind farms have been built in coastal waters. And scientists have found that, like many human-made structures sunk into seas’ depths, the underwater portions of giant windmills have served as the basis of artificial reefs that become home to mussels, crabs and other aquatic life.

And those aquatic creatures may be drawing even bigger marine life. A handful of harbor seals appear to be regularly visiting wind farms in their foraging efforts off the shores of Germany and England, Deborah J.F. Russell of the University of St. Andrews in Scotland and colleagues report July 21 in Current Biology.

The tracks of one harbor seal that visited the Alpha Ventus wind farm follow the grid pattern of the turbines. Red indicates areas where the seal probably foraged for food at the base of the turbines and at a meteorological mast located to the west. D.J.F. Russell et al/Current Biology 2014
Russell and colleagues tagged harbor and grey seals on the British and Dutch coasts of the North Sea with GPS trackers and mapped out where the marine mammals traveled from day to day. These seals will leave land and spend several days to a whole month at sea in their search for food.

Eleven harbor seals visited two active offshore wind farms — Alpha Ventus off Germany and Sheringham Shoal, located off the southeastern coast of England. Wind farms are set up in a grid pattern, with the windmills set at regular distances from each other. When three of the 11 seals visited the farms, they followed this grid, moving from windmill to windmill and concentrating their time at each turbine instead of in the spaces in between.

Their movements slowed at those spots, which is indicative of foraging behavior — they were probably searching for food, the researchers say. And those three seals kept coming back to the wind farms, which means they probably had successful hunts.

The researchers think that these 11 seals might be pioneers of their species. The wind farms were relatively new in the area and would represent a novelty to the seals. These seals might have been the ones that were more likely to try out new things, and a few of them found that they had hit the jackpot. 

Sarah Zielinski is the Editor, Print at Science News Explores. She has a B.A. in biology from Cornell University and an M.A. in journalism from New York University. She writes about ecology, plants and animals.

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