Scientists have located in Antarctica the largest fish colony in the world, coming into contact with a unique marine ecosystem, which is the size of Malta.
The colony, which is estimated to be the nest for 60 million fish and the largest fish breeding ground in the world, was found in the Weddell Sea region, whose surface is covered by a layer of ice 3-4 meters high. According to scientists, at the bottom of the sea are the so-called ice fish, a species of fish that has transparent blood, as it is the only vertebrate without red blood cells.
To survive at such low temperatures, these fish have developed an antifreeze protein, which prevents the formation of ice crystals. The huge colony was discovered in February 2021 by the German research vessel Polarstern, which was looking for traces of life.
“We saw fish nests for about four hours at a distance of up to six kilometers from the seabed,” said Autun Purser, a researcher at the Alfred Wegener Institute in Germany. “I have never seen anything like it.”
The colony covers more than 240 square kilometers, while each nest occupies about three square meters, has a depth of 15 cm and contains about 1,735 eggs. Most nests were “guarded” by other, larger fish.
While the Weddell Sea is covered in ice all year round, the ice is relatively thin – a meter thick – which means photosynthesis can be made and life can thrive. Purser said the Weddell seabed is not barren at all, with marine sponges, corals, octopuses and starfish lying along the seabed.
About 2,000 seals also live in the area and are likely to dive into the breeding area and feed on fish, he said, although there is no evidence yet. Purser said that while there are freshwater fish species that make similar nest species, scientists “have never seen such colonies at sea.” “I guess we've only filmed maybe 1% of the Weddell seabed and who knows what else is hiding around this place. “I am convinced that there are many gaps in our knowledge of the sea.”
