A crew of marine biologists from Scotland and New Zealand, who just returned from a deep-ocean expedition to one of the deepest places on Earth – the Kermadec Trench, has announced the discovery of a new eelpout species at depths of more than 13,900 feet (4,250 m).

The scientists returned from a two-week survey to the north of New Zealand, near the Kermadec Islands, with photos and footage of new-to-science fish. They onboard the research vessel RV Kaharoa used landers with cameras attached that free-fall to the seafloor, as well as baited fish traps to attract the animals.

“We are never quite sure what we will find on these expeditions to unchartered territories. We had set out to find out more about the deep sea fish communities and we were delighted to find both new species and new depth records for fish,” said voyage leader Dr Alan Jamieson of the University of Aberdeen’s Oceanlab.

“The international collaboration enables New Zealand researchers to use scientific equipment we don’t have, and to sample places that would otherwise be inaccessible, and hence unknown,” added Dr Malcolm Clark of the National Institute of Water and Atmospheric Research, New Zealand.

The team also discovered new depth records of 18,000 feet (5,500 m) for a rattail fish that hasn’t previously been caught in the southwest Pacific, another rattail that hasn’t been caught in New Zealand waters for over 100 years and a large deep sea cusk eel.

One of the species of rattail found by the scientists, called the Cosmopolitan Rattail, was first caught off New Zealand by the HMS Challenger in a global scientific expedition in the 1870s.

“The results from this deep exploration are giving us a much better understanding of biodiversity in the deep sea around New Zealand, and enable us to better assess potential risks to the ecosystem from future climate change and even human activities which may include seabed mining,” Dr Clark said.

“A voyage such as this is testament to how feasible scientific research in the deep sea has become. It is no longer the inaccessible, out of reach, part of the world it once was. The technological challenges of the past are being overcome, and shouldn’t limit our responsibility to learn about and understand the deep sea to help ensure the long term health of the deep oceans – one of the largest environments on Earth,” Dr Jamieson said.