Scientists have discovered a new species of fish in an area where it was thought was completely devoid of fish.
The team of marine biologists from Aberdeen, Tokyo and New Zealand have found a new species of snailfish at a depth of 7000m in the Peru-Chile trench in the South East Pacific Ocean. This is an area where previously no fish have ever been captured.
Mass groupings of cusk-eels and large shrimp-like scavengers called Eurythenes were also discovered living at these depths for the first time. Further research is currently being done to see if the cusk-eels may be a new species too.
The expedition, which took three weeks, used state-of-the-art deep-sea imaging technology such as an ultra-deep free-falling baited camera system to take 6000 images between 4500 and 8000m deep.
Dr Alan Jamieson from the University of Aberdeen's Oceanlab, who led the expedition said: "Our findings, which revealed diverse and abundant species at depths previously thought to be void of fish, will prompt a rethink into marine populations at extreme depths.
"This expedition was prompted by our previous findings off Japan and New Zealand where we discovered new species of snailfish known as Liparids, with each trench hosting its own unique species of the fish.
"To test whether these species would be found in all trenches, we repeated our experiments on the other side of the Pacific Ocean off Peru and Chile, some 6000 miles from our last observations.
"What we found was that indeed there was another unique species of snailfish living at 7000m - entirely new to science, which had never been caught or seen before."
Dr Toyonobu Fujii, a deep-sea fish expert from the University of Aberdeen said: "How deep fish can live has long been an intriguing question and the results from this expedition has provided deeper insight into our understanding of the global distribution of fish in the oceans."
Dr Jamieson added: "These findings prompt a re-evaluation of the diversity and abundance of life at extreme depths. Furthermore, it is now apparent that each of the deep trenches across the globe hosts a unique assembly of animals which can differ greatly from trench to trench. The immense isolation of each trench draws parallels with island evolution theory popularised by Darwin's finches."
The expedition is the seventh to take place as part of HADEEP - a collaborative research project involving the University of Aberdeen's Oceanlab and the University of Tokyo's Ocean Research Institute, with support from New Zealand's National Institute of Water and Atmospheric research institute (NIWA).