The researchers unexpectedly discovered the largest group of nesting fish – Icefish, under the Antarctic ice while surveying the seafloor life on an ice-breaking research vessel.
The finding came as a surprise to the scientists. Until this finding, the deep-sea biologists recorded only a few clusters of Icefish nests in one place.
In the Weddell Sea, five hundred meters below the ice, the researchers found an estimated 60 million nests of the Icefish spread across 240 square kilometers (i.e roughly the size of Orlando).
The fish belongs to the Channichthyidae family which scientists believe has a deep influence on Antarctic food webs, and the research report was published in Current Biology.
In 2021, while mapping the seafloor’s life using the deep-sea cameras towed by the research vessel in the Weddell Sea, located between the Antarctic Peninsula and the main continent, Deep Sea biologist Autun Purser along with his colleagues came across a huge colony of Icefish.
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The scientists were tasked to study the chemical interactions between surface waters and the seafloor. While video-recording the seafloor to map seafloor features at one location on the Filchner ice shelf, the device that was being towed encountered circular Jonah’s icefish nests and constantly recorded the nests for 100s of kilometers.
These fishes have adapted to the extremely frigid temperatures as their blood contains antifreeze agents.
“When I came down half an hour later and just saw nest after nest the whole four hours of the first dive, I thought we were onto something unusual,” Purser said in a report.
Then the search and recording were focused on the nests kilometer after kilometer. Based on their calculations with one nesting fish per four square meters for more than 240 kilometers of the seafloor, the researchers estimated about 60 million nests.
“The Weddell Sea Colony is several orders of magnitude larger,” the researchers stated. However, they aren’t completely sure about what drove them to gather a colony this big.
The researchers estimated that the area is plankton-rich which would be a nurturing environment for the hatchlings, they also found the water was slightly warmer in the region, suitable for breeding.
The discovery of the world’s largest nesting fish- Icefish colony could intensify the argument for declaring these regions of the Weddell Sea as ‘protected.’
The researchers are hoping to find more secrets about this new colony.