Southern hemisphere's deepest fish caught on camera
12 November 2009, by Tom Marshall
Scientists have photographed the deepest fish ever filmed in the Southern hemisphere, and the second-deepest seen anywhere in the world.
They took around 1000 pictures of swarms of the snailfish Notoliparis kermadecensis nibbling at bait 7560 metres below the surface - just short of the 7700 metre record depth at which the same team managed to film similar fish in the Japan Trench in late 2008.
They did this with a specially-built unmanned submersible designed to sink in free fall several kilometres down into the Kermadec Trench, northeast of New Zealand. When it reached the seabed it used a downward-pointing camera to photograph the creatures that were attracted to the dead fish used for bait.
It's the latest success for the Hadeep project, a collaborative effort between the University of Aberdeen's Oceanlab and the Ocean Research Institute at the University of Tokyo investigating sea life in the world's deepest ocean trenches.
The deepest fish ever found in the southern hemisphere, the snailfish Notoliparis kermadecensis.
The project aims to shed light on the ecology of the Hadal zone, the deepest part of the ocean from 6000 metres down. The creatures that live here have to be adapted to cope with crushing water pressure and extreme cold in the lightless depths. Most depend on dead organic matter falling down from the waters above for food.
The research fills in gaps in our knowledge of the ecology of deep ocean trenches. The team launched their landers at different depths across the Kermadec trench, to give an idea of how communities of deep-sea animals vary with depth.
This cruise took place with the help of New Zealand's National Institute of Water & Atmospheric Research, who provided the RV Kaharoa, the research ship the team used to launch their landers.
Earlier in the voyage disaster struck when the team's main lander, nicknamed 'Alfie', was lost after apparently tipping over and becoming stuck on its side on the seabed. Alfie was the lander responsible for the Japan Trench footage, and had been used in water as deep as 10 kilometres all over the world.
The HADEEP-Kaharoa team (L-R) Toyonobu Fujii, Kota Kitazawa, Alan Jamieson and Ashley Rowden.
But the team's backup lander 'Jonah' came through, despite limited activities in the Hadal zone before this. Unlike Alfie, Jonah wasn't equipped with a video camera, but it returned to the surface with striking photgraphs of large numbers of snailfish. Notoliparis kermadecensis lives only in the Kermadec Trench, and since it was discovered in 1952 has been photographed just once before, on a previous Hadeep cruise in 2007.
'Our results show that this fish lives between 7000 and 8000m right from the north to the south of the Kermadec Trench,' wrote Dr Alan Jamieson of Oceanlab, leader of the expedition in his Planet Earth Online blog. 'They don't appear to go shallower, they don't appear to go deeper; they just like that long sliver of a contour. The question is, do they live on both the east and the west flanks of the trench?'
Hadal-Lander A ('Alfie') and Hadal-Lander B ('Jonah') on the RV Kaharoa's deck before launch.
The expedition's results will be important in building up a complete picture of trench life. On the relatively shallow abyssal plain stretching away to the side of the ocean trench, less than 5000 metres deep, the team has found scavengers such as Grenadier fish, eels and prawns, while beyond 7000 metres the dominant animals seem to be amphipods (a class of shrimp-like crustacean) and liparid fish.
But In the space in between, around 6000 metres, the researchers found comparatively little life. 'The transition of scavengers into the trench is not really much of a transition,' Jamieson commented. 'Something prevents the trench animals from getting up and out onto the plains, and the guys on the plain seem reluctant to venture into the trench, leaving this weird 'no man's land' at around 6000 metres.'
The Hadeep Project has been funded by the the Nippon Foundation in Japan since 2006 and the Natural Environment Research Council in the UK since 2007. Program leader for the project is Professor Mutsumi Nishida, director of the Ocean Research Institute at the University of Tokyo. The project was devised by Professor Monty Priede, director of Oceanlab.
Follow the expedition on Alan Jamieson's 'Return to the Abyss Down Under' blog on Planet Earth Online, in the links to the right.
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