The source: Scientific news
A new study has described the largest school of fish ever seen, at a depth of about 1,600 feet and spanning at least 90 square miles under the ice shelf in the Weddell Sea near Antarctica. It’s an area roughly the size of Orlando. The vast breeding grounds were discovered by Autun Purser from the Alfred Wegener Institute in Germany and his colleagues during a six-week expedition to the polar regions in February 2021, but this work has just been published in the journal Nature. magazine Current Biology.
The researchers were on board the RV Polarstern analyzed the seabed using the Ocean Bottom Observation and Measurement System (OFOBS), a one-ton camera towed behind the ship. (“It was an ordinary Canon camera that you could buy at any store,” says Purser. “It was in the frame of 3.5 million euros.”) Lilian Böhringer, one of the students Purser’s graduate, who was monitoring the camera feed, began to notice the nests of fish marking the seafloor in all directions. “The camera is moving [across the seafloor] and it doesn’t stop,” said Böhringer. “They were everywhere.”
The nests, modest bowls about 20 inches in diameter and 6 inches deep, were carved in the mud by Jonathan’s icefish (Neopagetopsis ionah), a small ray-finned fish native to the frigid Southern Ocean. Interestingly, these “white blooded” fish are the only vertebrates known to completely lack hemoglobin in their blood. Each nest contains one adult icefish and between 1,500 and 2,000 eggs, and scientists estimate the population contains at least 60 million nests — about 100 billion eggs in total. “It looks like the computer generated the structure of these nests,” says Purser.
Small schools of this icefish (with only dozens of nests) have been observed before, but relatively little is known about this species. Scientists believe the newly discovered colony is an important part of the local ecosystem, with adults feeding on Weddell seals and juveniles feeding on microscopic zooplankton found within the region. slightly warmer water in the area.
Purser and colleagues plan to return to the Weddell Sea in April. Watch videos of researchers explaining the discovery here.