Researchers from the University of Western Australia (UWA) and scientists from Japan have recorded a fish swimming at a depth of more than eight kilometers (about five miles), setting a record for the deepest fish ever caught on camera.
As part of a 10-year study of fish that live in the deepest areas of the oceans, UWA Professor Alan Jamieson, the founder of the Minderoo-UWA Deep Sea Research Centre and chief scientist of the expedition, worked with a team from the Tokyo University of Marine Science and Technology to deploy what are described as “baited cameras” in the deepest parts of the trenches located off the around Japan and the north Pacific Ocean.
The research vessel left on a two-month expedition last September and managed to capture footage of a fish in the Izu-Ogasawara Trench, which is south of Japan, of an unknown snailfish species of the genus Pseudoliparis at a colossal depth of 8,336 meters, or about 27,349 feet under the surface.
“We have spent over 15 years researching these deep snailfish; there is so much more to them than simply the depth, but the maximum depth they can survive is truly astonishing,” Professor Jamieson explains on the UWA website.
“In other trenches such as the Mariana Trench, we were finding them at increasingly deeper depths just creeping over that 8,000 meter mark in fewer and fewer numbers, but around Japan they are really quite abundant,” he continues. “The Japanese trenches were incredible places to explore; they are so rich in life, even all the way at the bottom.”
Snailfish aren’t rare, but this particular species hasn’t yet been observed. That isn’t particularly surprising given the depths they were observed at and the fact that the snailfish family contained more than 30 genera and about 410 described species — even more if undescribed species are considered. They live at a variety of depths ranging from shallow water to very deep, but this particular instance is the first time they have been actually observed swimming at the greater end of that incredible depth.
The researchers observed a large population of the snailfish during the research outing, but the footage of the single snailfish was an extremely small juvenile, as they tend to operate inverse to how other deep-sea fish live, as the youngest and smallest live at the deeper end of their depth range and move up as they age and grow larger.
The researchers collected two other fish from a depth of 8,022 meters, which are the first to be caught at a depth greater than eight kilometers.
“The real take-home message for me, is not necessarily that they are living at 8,336m but rather we have enough information on this environment to have predicted that these trenches would be where the deepest fish would be, in fact until this expedition, no one had ever seen nor collected a single fish from this entire trench,” Professor Jamieson says.