A researcher glues a small transmitter onto the fur behind a seal’s head and lets the animal go.<\/p>\n
Months later the tracks come back as lines on a chart<\/strong>, and most of them wander the way you would expect.<\/p>\n A few do not. A few run dead straight<\/strong>, then turn at a right angle, then run straight again.<\/p>\n Laid over a map of an offshore wind farm, those lines land on the towers.<\/p>\n The number of animals doing it is smaller than the headlines<\/strong>, and more interesting than they make it sound.<\/p>\n Dozens of harbor and grey seals were tagged along the British and Dutch coasts, and the great majority never went near a wind farm at all.<\/p>\n Eleven harbor seals did swim inside the two farms being watched, which is the number that usually gets quoted.<\/p>\n But only three of those eleven<\/strong> traced the grid, moving tower to tower rather than crossing the open water between them.<\/p>\n What made it read as hunting was the speed. Those animals slowed at each leg<\/strong>, and a seal that slows down is a seal that is working.<\/p>\n Two others did something stranger off the Dutch coast, following a seabed pipeline<\/strong> on repeated trips of up to ten days.<\/p>\n So the honest version is three animals out of eleven, and eleven out of dozens, which is a small signal rather than a rule.<\/p>\n That is still the first time anyone had watched a wild predator at sea use a human layout as a route.<\/p>\n Neither site is enormous, and the difference between them is part of the point.<\/p>\n Sheringham Shoal sits about 11 miles off Norfolk<\/strong> in water between 52 and 72 feet deep, with 88 turbines rated at 3.6 megawatts apiece.<\/p>\n That comes to 317 megawatts in total, and the site has been turning since late 2011, so the growth on its legs has had years to build up.<\/p>\n Alpha Ventus is far smaller, just 12 turbines<\/strong> of 5 megawatts each for 60 megawatts total.<\/p>\n It stands 28 miles north of the island of Borkum in about 100 feet of water and went commercial in 2010.<\/p>\n Both are laid out on a regular grid, because that is how you stop one turbine stealing another’s wind, and regular spacing<\/strong> is exactly what the tracks matched.<\/p>\n The seabed under both farms is soft, and soft bottom offers almost nothing to hold onto.<\/p>\n Drive steel into it and the surface starts filling within months, first with barnacles and mussels<\/strong>, then anemones and worms.<\/p>\n Rock is usually dumped around the base as scour protection, which adds gaps and crevices on top of the tower itself.<\/p>\n Small fish come for the growth. Bigger fish come for the small fish<\/strong>.<\/p>\n None of which the seal cares about directly. It cares only that the fish are in a known place rather than scattered thinly across open sand.<\/p>\n Swimming a straight line between reliable spots beats searching, which is the whole advantage<\/strong> the grid hands them.<\/p>\n The other half of this is less comfortable and it comes earlier in a project’s life.<\/p>\n During pile driving, seal numbers within about 15 miles<\/strong> of the work dropped by somewhere between 19 and 83 percent, which worked out to roughly 440 animals pushed off, as the follow up<\/a> found.<\/p>\n That is a real cost, it lasted for the whole construction season, and it belongs in the story rather than buried under the nice part.<\/p>\n What is equally real is how fast it ended. Within two hours<\/strong> of the hammering stopping, the animals were spread out exactly as they had been before it started.<\/p>\n And the finished, spinning wind farm produced no measurable displacement<\/strong> at all, as the tracking<\/a> set out.<\/p>\n The same split shows up around any offshore array<\/a> or fenced solar site<\/a>, where the building is the disturbance and the standing structure is not.<\/p>\n Three seals is not a population, and none of the people who did the work claim otherwise.<\/p>\n It shows the behavior is available to the species<\/strong>, not that most of them use it.<\/p>\n What gives it weight is the timing, because Europe is now deciding what to do with turbine foundations as the first farms reach the end of their lives.<\/p>\n Pulling the steel out removes the structure. Leaving it removes the reef with it<\/strong> only if you take the whole thing.<\/p>\n Tracks like these are the sort of evidence that argument has been short of, and there are far more foundations<\/strong> going in every year.<\/p>\n Whatever gets decided, part of the case will rest on three animals that swam in straight lines and stopped at every tower.<\/p>\n","protected":false},"excerpt":{"rendered":" A researcher glues a small transmitter onto the fur behind a seal’s head and lets the animal go. Months later the tracks come back as lines on a chart, and most of them wander the way you would expect. A few do not. A few run dead straight, then turn at a right angle, then run straight … Read more<\/a><\/p>\n","protected":false},"author":28,"featured_media":31489,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"rank_math_focus_keyword":"north sea seals","rank_math_title":"Tags on North Sea harbor seals showed 11 of them swimming inside 2 offshore wind farms, and 3 worked the turbines row by row like a grid, stopping at each leg to hunt","rank_math_description":"GPS tags on 118 North Sea seals revealed 11 hunting Sheringham Shoal's 88 turbines in a perfect geometric grid \u2014 a foraging strategy never before recorded","footnotes":""},"categories":[8],"tags":[],"class_list":["post-31331","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-energy"],"_links":{"self":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts\/31331","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/users\/28"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/comments?post=31331"}],"version-history":[{"count":0,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts\/31331\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/media\/31489"}],"wp:attachment":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/media?parent=31331"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/categories?post=31331"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/tags?post=31331"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Three seals, not eleven<\/h2>\n
The two farms in question<\/h2>\n
Why a foundation turns into a meal<\/h2>\n
What the hammering does first<\/h2>\n
What it proves and what it does not<\/h2>\n