IFCA Officer Doug Holt helps to release the glider that was found on Bryher
The mysterious underwater ‘gliders’ that have been surveying the waters around Scilly for the past two months have finally finished their mission. David White from the National Oceanography Centre in Southampton said the last of the two yellow, torpedo-shaped units was picked up yesterday around 7 miles west of Bishop Rock.
Most people are familiar with the gliders after one was rescued by Richard Pearce. It was washed up by his house on Bryher. David says he’s grateful to Richard for preventing the unit getting damaged. But while each one costs a lot, there isn’t much of a second hand market if you do find one. David says local IFCA Officer Doug Holt helped them re-release that one 20 miles north of Scilly.
The gliders are miniature robotic submarines, about 2 metres long, which can stay at sea for months at a time carrying out scientific measurements. They “fly” between the surface and a depth of up to one kilometre at a speed of half a knot. And when one surfaces, it gets a GPS fix, which is beamed back to its controllers in Southampton, together with any data it’s collected.
David says if it runs into trouble, like on Bryher last month, it calls for help, although on that occasion all they could do was watch as it ran aground because the water was too shallow to escape.
The gliders operating around the north and west of Scilly this year are part of a Defra study into the marine life in areas where the deep ocean water meets the continental shelf. They have a fish-finding echo sounder to map shoals as the glider flies over them. It’s hoped this could replace the normal method of surveying fish by scooping them up in a net.
A new sensor being tested on the gliders records clicks and whistles from dolphins, porpoises, seals and small whales. It found plenty of dolphins and gannets, said David, indicating an abundance of food. Other instruments measure the water temperature and salinity, as well as the amount of plankton.
David says more missions will be run next year, although these are likely to be much further out in deeper water to the south and west of the islands. Some of that data, as well as a map of the glider tracks can be seen on the NOC website.