Discoveries from the deep
Several ‘‘weird and wonderful’’ sea creatures new to science may have been discovered in an expedition to record hoki numbers this summer. Jennifer Eder reports.
Every two years, Niwa scientists spend several weeks at sea, trawling the depths to check on New Zealand’s favourite fish ‘n’ chip shop fish.
They drag a net through the sea in random zig-zags, from Wellington to the Chatham Islands, about 800km east of the South Island, and back to Lyttelton, through an area known as the Chatham Rise. Their goal is to establish the size of the juvenile hoki stock, which will help decide how big fishing quotas should be.
But along the way, they catch all sorts of ‘‘weird and wonderful’’ species - including creatures entirely new to science.
Niwa fisheries scientist Dr Richard O’driscoll says during the latest biennial survey his team caught 128 unidentifiable animals 73 fish and 55 invertebrates.
Most of these species are so unusual scientists on board cannot identify them by sight, which is why they are collected and sent for assessment, he says.
In some cases the creatures have never before been recorded.
‘‘Most of the time we can confirm things ourselves but you do get things that are new to science. And often you don’t know about it until later, after someone analyses it,’’ O’driscoll says.
His favourite part of the job is that he still gets to experience these new discoveries, even though he has been researching at sea for 18 years, he says.
‘‘That’s one of the things that gives me a real buzz. Just about every time I go out I see something I’ve never seen before.’’
Invertebrates, such as crabs, octopuses, starfish and jellyfish, are sent to Niwa’s national invertebrates collection for identification, while ‘‘the fishy things’’ are sent to Te Papa’s fish collection in Wellington, O’driscoll says.
‘‘Some stuff we bring back on request, such as catsharks. They originally thought there was only one type [on the Chatham Rise], but now they think there’s more like five or six different species.’’
He has yet to learn if there are any new discoveries from this year’s trawl, and he doesn’t know how long he’ll need to wait to find out, he says.
‘‘I think they’re still in biosecurity containment at the moment. Anything from more than 12 nautical miles out is considered a biosecurity risk.’’
The research team are very familiar with fish, so it was usually other species sent back for identification, O’driscoll says.
And when a completely new species was found - not on every trip, but once in a while - it is usually something small and less interesting-looking, he says.
‘‘I have colleagues who have had new species named after them. I believe it’s bad form to name something after yourself, but you can name it after the person who gave it to you. But you never want to have a parasite named after you, do you?’’
This summer marks the seventh research voyage trawling depths down to 1300 metres. It was an annual voyage until 2014 when it became biennial.
Before 2010, the survey was only to a depth of 800m, but the survey changed to include numbers of species that are often caught accidentally by fishers (known as by-catch) and the depth changed as a result.
‘‘We weigh and measure everything we catch,’’ O’driscoll says.
On the most recent trip, he and his team have measured 71,752 fish - so many that laid end-to-end they would stretch for 31km.
‘‘We took some students out funded by the Sir Peter Blake Trust and it’s always interesting to see it through their eyes. Everything we catch, they go, ‘wow, what’s that?’’’
The data collected about hoki numbers will inform the Ministry for Primary Industries, and help set the quota limit for the next two years.
Hoki is one of the most popular commercially-caught fish, served battered or crumbed in fish n’ chip shops, used by fast food chains in fish burgers, and sold in supermarkets fresh or frozen.
Last year’s catch brought in $229 million.
The hoki quota was dropped from 250,000 to 90,000 after several years of a shortage of young fish.
But the quotas have gradually increased as the stock increased, and this year the quota is set at 150,000.
O’driscoll likens the changing quota system to a bank account.
‘‘You’ve got deposits going in that’s new fish being born - and you’ve got payments going out that’s the fish we catch. If you don’t have any deposits going in, your bank balance just keeps going down. And if we don’t make sure there’s enough baby fish replacing what we catch, and keep increasing our withdrawals, we’ll run out.
‘‘But as long as we keep getting enough deposits, we can keep our fisheries stable.’’