At first glance, offshore wind farms and wildlife do not appear to go together. For one, the noise that these giant turbines generate could scare away marine animals. The development of offshore wind farms also raise concerns of potentially putting the lives of certain species at risk, such as seabirds getting struck by the blades and causing the displacement of marine animals from their natural habitat.
Seals, however, appear to have a growing fondness for offshore wind farms and an investigation conducted by a team of international researchers from the U.S., the Netherlands and the U.K offers a plausible answer.
For the study "Marine mammals trace anthropogenic structures at sea" published in the journal Current Biology on July 21, Deborah Russell, from the Sea Mammal Research Unit of the University of St. Andrews in the U.K, and colleagues tracked over 100 harbor seals and grey seals that have been tagged with GPS trackers and found that 11 have visited the Alpha Ventus and the Sheringham Shoal wind farms in the North sea with several of the meat-eating mammals becoming regular visitors to these areas.
"I was shocked when I first saw the stunning grid pattern of a seal track around Sheringham Shoal," Russell said. "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."
The seals may be frequently visiting offshore wind farms and pipelines but they are not likely drawn to the structures in particular. Instead, they see these as attractive hunting grounds as these anthropogenic structures also serve as artificial reefs.
The researchers said that they do not know what particular species of prey that the seals hunt and eat in the area but it appears that the animals had success in hunting for food in offshore windmills and pipelines because they keep going back to these structures.
"The data strongly suggest that these structures were used for foraging and the directed movements show that animals could effectively navigate to and between structures," the researchers wrote. "The individuals utilizing structures often did so repeatedly, suggesting that, at least for them, it represents successful foraging behavior."
Russell and colleagues, however, pointed out that the impact of the wind turbines as artificial reefs isn't yet clear. Whether or not the wind farms actually boost the amount of prey, which is a good thing, or these simply concentrate the prey in one location making them an easy target for predators is yet to be determined.