The scientists found these three seals were part of a group of 11 seals that swam within two active offshore wind farms - Alpha Ventus off the coast of Germany, and Sheringham Shoal off the east coast of England. The grid patterns of the seals' movements showed how the animals swam in straight lines between wind turbines.
"We could actually pinpoint where the wind turbines were by looking at the paths the seals traveled," Russell told Live Science.
The scientists also saw both gray and harbor seals visiting offshore oil and gas pipelines. Researchers observed two harbor seals in the Netherlands following sections of pipeline on multiple trips lasting up to 10 days each.
The researchers suggest these man-made structures may act like artificial reefs that shelter potential prey, making the areas attractive hunting grounds for the seals. "This is the first time marine mammals have shown use of these artificial structures for foraging," Russell said.
It remains uncertain what the environmental consequences of offshore wind farms will be for seals and their prey. If these farms increase the total amount of prey available for seals, "then the effects may be positive overall," Russell said. "However, if they are simply concentrating existing prey and making them vulnerable to predation to animals such as seals, that could deplete the populations of those prey."