- The vast breeding colony was discovered in February 2021
- The researchers estimated that the colony includes about 60 million active nests
- The study on the icefish colony was published in the journal Current Biology
A breeding colony of 60 million fish has been discovered in the ice-covered Weddell Sea in Antarctica. The previously unknown ecosystem covers an area the size of Malta.It is believed to be the world's largest fish breeding colony.The vast colony has icefish (Neopagetopsis ionah), which have a see-through skull and transparent blood. Icefish are the only vertebrates to have no red blood cells.The fish have evolved an anti-freeze protein in their transparent blood to stop ice crystals from growing and thus,survive at such low temperatures.The breeding colony was discovered in February 2021 by the German polar research vessel Polarstern.
The expedition was surveying ocean currents when the researchers made the surprising discovery.The study on the icefish colony was published in the journal Current Biology on Thursday."We just saw fish nest after fish nest for the whole four hours, and during that time we covered maybe six kilometres (3.7 miles) of the sea floor," Autun Purser, lead author and postdoctoral researcher at the Alfred Wegener Institute in Bremerhaven, Germany, told CNN.
"I'd never seen anything like it in 15 years of being an ocean scientist," Purser said. "After that dive, we emailed the experts on shore who know about fish like this. They said, yep, this is pretty unique."The colony covers more than 240 square kilometres. The researchers estimated that the colony includes about 60 million active nests, with one nest covering three square metres on average.The evenly spaced nests were about 15 centimetres deep and 75 centimetres in diameter.
They contained on average 1,735 eggs. Most of the nests were guarded by oneadult fish. Some contained only eggs, while others were unused.Two camera systems have been set up to monitor the icefish nests until a research vessel returns to get more details about the fish nest ecosystem.