By hoki, there’s something fishy here
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 – hoki.
They drag a net through the sea in random zig-zags, from Wellington to the Chatham Islands 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 fishing quotas.
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 that during the latest survey his team caught 73 fish and 55 invertebrates which scientists on board could not identify.
In some cases the creatures have never before been recorded.
Invertebrates, such as crabs, octopuses, starfish and jellyfish, are sent to Niwa’s national invertebrates collection for identification, while ‘‘the fishy things’’ go to Te Papa’s fish collection in Wellington, O’Driscoll says.
He has yet to learn if there are any new discoveries from this year’s trawl.
‘‘I think they’re still in biosecurity containment at the moment. Anything from more than 12 nautical miles out is considered a biosecurity risk.’’
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 this was extended when it began to include by-catch.
On the most recent trip, he and his team measured 71,752 fish.
‘‘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
You never want to have a parasite named after you, do you? Niwa fisheries scientist Dr Richard O’Driscoll
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 and last year’s catch brought in $229 million.
The 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.
‘‘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,’’ O’Driscoll says. ‘‘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.’’