As unbelievable as it sounds, it was not known to exist. And it is the largest fish colony in the world. It is a unique and previously unknown ecosystem. Who found it? German scientists. They were studying ocean currents in the Weddell Sea, in Antarctica. And a spawning colony of some 60 million ice fish turned up.
They are fish with a large head and clear blood. They are the only vertebrates that do not have red blood cells. How do they survive low temperatures? They produce an antifreeze protein that prevents the growth of ice crystals.
The colony covers an area of more than 240 square kilometers. It is a concentration of fish nests about 15 centimeters deep and 75 centimeters in diameter. They are lined with small pebbles in a circle. On average, the nests are separated by 1.7 meters. Each contains between 1,500 and 2,500 eggs.
The world’s largest fish colony was found in February 2021. The German polar research vessel Polarstern surveyed the seafloor. It used a car-sized camera system attached to the stern. Finding this came as a complete surprise to the researchers.
Four more expeditions were conducted. They revealed the enormous size of the nesting colony and its surprising uniformity. Most of the nests are guarded by adult fish. They have now installed two camera systems at sea to monitor the colony. More details about the fish nest ecosystem will be available soon.
This is the first time researchers have found something like this in a deep, cold sea. The researchers believe that icefish are attracted to the warmer water. It is only about 2 degrees Celsius warmer than the surrounding seafloor. All around, the temperature is 0 degrees Celsius.
According to the researchers, the results show a completely unique ecosystem. Therefore, this area of the Weddell Sea should be declared a protected area.