NIWA goes deeper than ever before, and finds new strange-looking fish

NIWA scientists trawled deep – deeper than ever before – down to 2,730 metres, and found new-to-science fish close to the deep ocean seafloor during their latest research voyage.

Working from the research vessel Tangaroa, the scientists explored the deepest ocean to increase their knowledge of fish distribution, abundance, and ecology.

The eight deepest-ever fish trawls ever carried out by NIWA sampled depths from 1,910–2,730 metres, northwest of the Graveyard Hills on the north Chatham Rise.

Below 2,100 metres, the scientists found that there weren't many fish; only a small numbers of skates, slickheads, rattails, and cusk-eels were caught there.

New Zealand's Exclusive Economic Zone (EEZ) is over 4 million square kilometres and just over half that area is deeper than 2,000 metres.

The Ministry for Primary Industries Dr Pamela Mace says, "We are interested in these results because they test whether our assumptions about the depth limits of commercial fish species are correct, and they also increase our knowledge about the inhabitants of our marine estate in this largely unexplored environment."

The trawls revealed truly fantastic looking new-to-science and rare fishes: a flabby whalefish, 3 new slickheads, a juvenile Richardson's skate, large warty cusk-eel, new record of a white rattail, and several unidentified fishes .

NIWA fisheries scientist Peter McMillan says, "We were fortunate to get an opportunity to explore this deep area on the Chatham Rise. It's great to know what we have, and how much."

It's hard work for the scientists exploring this deep. To send a net to the bottom of the sea floor at 2,000 metres and get it back can take three hours or more. Deepsea fish often appear to have bizarre body forms compared with the more commonly studied inshore fishes.

Shortly after the fish are brought up from the depths of the ocean, NIWA scientists take photos of the fish to capture their fresh colour. The catch from each station is recorded and then specimens are labelled and frozen.

NIWA gifts the rare and the new-to-science fish at Te Papa where they are preserved, researched and stored in the National Fish Collection.

In the Fishes Collection at Te Papa, preserved fish specimens are held from 28 sites below 2,000m. Of these, 120 specimens covering 34 species are represented. The majority were caught by the New Zealand Oceanographic Institute and, more recently, by NIWA.

The voyage was funded by Land Information New Zealand's Ocean Survey 20/20 programme and the Ministry for Primary Industries.

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Peter McMillan
Close up of one large white rattail (genus Coryphaenoides) caught at about 2,600 m. Not previously recorded from New Zealand waters. Rare. (Credit: Peter McMillan)
Peter McMillan
One large white rattail (genus Coryphaenoides) caught at about 2,600 m. Not previously recorded from New Zealand waters. Rare. (Credit: Peter McMillan)