Deepest-living fishes caught on camera for the first time

7 October 2008 by Tom Marshall

Marine scientists filming in one of the world's deepest ocean trenches have found groups of highly sociable fish swarming nearly five miles (7700 metres) beneath the surface.

Snail fish

The first photograph of the world's deepest living fishes: swarms of snail fish (Liparidae) attacking bait at 7,703m in the Japan Trench

When the international team recovered their high definition cameras from record-breaking depths in the Pacific Ocean, they were astounded by the abundance of life.

The footage shows swarms of fish darting over bait under pressures equivalent to 1600 elephants on the roof of a mini. This is the first time life at these depths has been caught on camera.

"We got some absolutely amazing footage from 7,700 metres. More fish than we or anyone in the world would ever have thought possible at these depths," says project leader Dr Alan Jamieson on board the Japanese research ship the Hakuho-Maru.

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"It's incredible. These videos vastly exceed all our expectations from this research. We thought the deepest fishes would be motionless, solitary, fragile individuals eking out an existence in a food-sparse environment," says Professor Monty Priede, director of Oceanlab, based at the University of Aberdeen.

Hadeep team

The Hadeep team

"But these fish aren't loners. The images show groups that are sociable and active - possibly even families - feeding on little shrimp, yet living in one of the most extreme environments on Earth."

"All we've seen before of life at this depth have been shrivelled specimens in museums. Now we have an impression of how they move and what they do," he added.

The fish are called snail fish (from the family Liparidae) and are found exclusively below 6,000 metres, where they contend with total darkness, near freezing temperatures and immense water pressure - equivalent to 1,600 elephants on the roof of a Mini. They feed on the thousands of tiny shrimp-like creatures that scavenge the carcasses of dead fish on the ocean floor.

Snail fish live only in a handful of trenches in the Pacific Ocean: the Kermadec and Tonga trenches situated between Samoa and New Zealand in the South Pacific, and the Japan trench, which Priede's team is currently investigating.

More fish than we or anyone in the world would ever have thought possible at these depths

- Dr Alan Jamieson

The work is part of the HADEEP project - a collaborative research programme between Oceanlab and the University of Tokyo. The project aims to investigate life in the hadal region of the ocean, which is anything below 6,000 metres.

Program leader for HADEEP is Professor Mutsumi Nishida, director of the Ocean Research Institute at the University of Tokyo. The project has been funded by the Nippon Foundation in Japan since 2006 and by the Natural Environment Research Council since 2007.

Submersible lander

With sapphire viewports and pressure housings as thick as cannon-barrels, the HADEEP submersible is made of stern stuff

This latest cruse to the Japan trench was funded by the Nippon Foundation via the University of Tokyo. It began on Wednesday 24 September and finished 6 October. It was organised by Dr Asako K Matsumoto, HADEEP research manager.

The deep-sea equipment needed to survive the extreme pressure at these depths was designed and built by the Oceanlab team specifically for this mission.

The submersible camera platforms take five hours to reach the depths of the trenches and remain on the seafloor for two days before the signal is given for them to surface.