World’s largest fish colony found in Antarctica
Scientists exploring the waters of Antarctica have discovered one of the most extraordinary ecosystems ever documented: the world’s largest breeding colony of fish.
It includes about 60 million active nests of a species known as jonah’s icefish, which makes circular indentations in the sediment of the sea bed. Altogether the colony covers at least 240 square kilometres.
Most of the nests, each about 75cm in diameter, are guarded by a single adult and contain about 1700 eggs. The fish are estimated to weigh a total of 60,000 tonnes. Until now it was not known that such a thing existed.
The colony was found by the crew of the German research vessel Polarstern. ‘‘A few dozen nests have been observed elsewhere in the Antarctic,’’ said Autun Purser of the Alfred Wegener Institute in Bremerhaven, who led the study. ‘‘But this find is orders of magnitude larger.’’
The researchers said its discovery bolstered the case for the creation of a new marine protected area in the Southern Ocean, a hostile and little-explored region.
Professor Antje Boetius, of the Max Planck Institute for Marine Microbiology, said: ‘‘It shows how important it is to be able to investigate unknown ecosystems before we disturb them.
‘‘Considering how little-known the Antarctic Weddell Sea is, this underlines all the more the need of international efforts to establish a marine protected area.’’
The team found the colony while surveying the Filchner ice shelf in the Weddell Sea, using a device known as the Ocean Floor Observation and Bathymetry System (Ofobs). ‘‘Basically this is a large, towed device, weighing one tonne, which we tow behind the icebreaker RV Polarstern at a speed of 1-4kmh,’’ Purser said. ‘‘We tow this at a height of about 1.5 to 2.5 metres above the seafloor, recording videos and acoustic bathymetry data.’’ The area was of interest because its waters, at between -1C and 0C, are about 2 degrees warmer than the surrounding area.