Frightening fishy finds

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NIWA looked deep – to almost 1840 metres – and found new-to-science fish, close to the seafloor. The ocean revealed specimens of some rarely seen, and some previously unknown, fishes from New Zealand waters.

“We were fortunate to get an opportunity to explore this deep on the Chatham Rise,” says NIWA fisheries scientist Peter McMillan.

Fisheries scientists know a lot about some commercial fish species, like orange roughy, yet even the orange roughy has secrets. Scientists on this voyage in June 2010 found out just how low they go – they found one specimen below 1500 metres.

“The deeper we go, the less we know. Our knowledge of fishes decreases with increasing depth. About 1170 fish species are known from the New Zealand region. Of these, only about 56 species have been recorded at depths greater than 1500 meters. Only one species has been captured at depths greater than 6000 metres in New Zealand - the Kermadec snailfish, at 6660 to 6890 metres,” says McMillan.

The scientists were exploring deepwater biodiversity to increase their knowledge of fish distribution, abundance, and ecology at great depths.

This RV Tangaroa research voyage trawled at depths as far down as 1837 metres and revealed a range of truly fantastic-looking new to science and rare fishes: a rare un-named species of lanternshark, a small-mouth grenadier, and a naked-snout grenadier.

Deepsea fish often appear to us to have bizarre body forms, compared to the more commonly studied inshore fishes. The fishes down deep have evolved to cope with life in relative darkness. They tend to have smaller eyes. Some fish even produce their own light – they have light-producing organs on their head or lower body. The temperature at this depth is only a few degrees.

As deepsea fish live under high pressure, the swim bladder, which shallow-water fish use to regulate buoyancy, is reduced or absent. Deepsea fish have often adapted to swallow large prey, and eat infrequent meals.

It’s hard work for the scientists exploring this deep. To send a net to the bottom of the sea floor at 2000 metres can take three hours. Any gear used at these depths is subject to huge pressures. The pressure at 2000 metres is about 200 times that encountered at the sea surface. As a result, less than 0.002% of New Zealand’s deepsea environment has been sampled. The area of the seafloor below 1500 metres covers more than 50% of New Zealand’s Exclusive Economic Zone.

This work was funded by the Ministry of Fisheries and Land Information New Zealand (LINZ).

NIWA gifts the rare and the new-to-science fish to Te Papa where they are preserved and stored by Andrew Stewart in the National Fish Collection.

 

It has a system of large sensory pores on the head, in front of the mouth, which probably help it locate food on or in the seafloor. This is the first survey where smaller individuals have been caught. The pointy nose ghost shark doesn’t have a swim bladder, but it has a large liver which helps with buoyancy.
Research subject: BiodiversityFish