Male icefish, part of a massive colony, guard their nests in the Weddell Sea. Photo: Alfred Wegener Institute.
At 60 million nests, the icefish colony stretches for 240 square kilometers
Erik Stokstad, Science, January 13, 2022
The most extensive and densely populated breeding colony of fish anywhere lurks deep underneath the ice of the Weddell Sea, scientists aboard an Antarctic research cruise have discovered. The 240 square kilometers of regularly spaced icefish nests, east of the Antarctic Peninsula, has astonished marine ecologists. “We had no idea that it would be just on this scale, and I think that’s the most fantastic thing,” says Mark Belchier, a fish biologist with the British Antarctic Survey and the government of South Georgia & the South Sandwich Islands, who was not involved in the new work.
In February 2021, the RV Polarstern—a large German research ship—was breaking through sea ice in the Weddell Sea to study marine life. While towing video cameras and other instruments half a kilometer down, near the sea floor, the ship came upon thousands of 75-centimeter-wide nests, each occupied by a single adult icefish—and up to 2100 eggs. “It was really an amazing sight,” says deep-sea biologist Autun Purser of the Alfred Wegener Institute, who led the ship’s underwater imaging.