The rare visitor was identified swimming through SSE Renewables’ Seagreen offshore wind farm site by HiDef Aerial Surveying Ltd, who had been commissioned by the renewable energy developer to undertake a series of digital aerial wildlife surveys over the offshore wind farm site, 27km off the east coast of Scotland in the western North Sea. The work was part of a wider surveying exercise carried out by SSE Renewables, EDF Renewables and Red Rock Power Limited.
Whilst analysing video footage recorded from the site in August 2019 ecologists noted an unfamiliar shape in the cool North Sea waters. With the ability to zoom in up to 700% it became clear that the sequence of images actually showed a Swordfish, an enigmatic species more accustomed to warmer waters in the Caribbean or Mediterranean. Swordfish are large, highly migratory, predatory fish characterized by a long, flat, pointed bill. This fish measured two metres and was recorded close to the sea surface.
With only a single known previous recording in Scotland, a second opinion was sought to confirm the team’s identification. Jim Ellis from CEFAS (Centre for Environment, Fisheries and Aquaculture Science) commented: “The distance from the tip of the bill to the origin of the first dorsal fin is a high proportion of the fork length. Marlins etc. have a proportionally shorter bill.” And so, the identification was ratified as a Swordfish, although not quite fully grown.
Walter Golet, from the University of Maine School of Marine Science, was also confident in the identification noting: “Swordfish have a huge latitudinal range and by the picture it appears to have a flat bill, and marlins (the only other confusion species) are all round.”
HiDef Associate Director Martin Scott said: “We have seen some incredible things over the years but this one is particularly gratifying. It shows how aware and alert our team are, not just on a day to day basis, but when confronted with an obscure oddity. With the aircraft flying at 200km per hour and 1800 feet up it really does just go to show how good our systems are at recording wildlife”
Lis Royle, Seagreen’s Consent Manager said: “We’re pleased we’ve been able to help record the second ever spotting of a swordfish in Scottish waters.
“It’s our duty to ensure that our projects are built with a detailed understanding of the natural environment and whilst we don’t expect the Seagreen swordfish to make an appearance again it was great to be able to capture this incredibly rare sighting during our survey work.”
HiDef would like to thank staff at SSE, Blue Planet Archive, Iain Stenhouse (BRI), Walter Golet (Gulf of Maine Research Institute), Jim Ellis (CEFAS)