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Bid to save native fish from extinction

Posted at 12:58pm Tuesday 04 Jun, 2019

Auckland Council has teamed up with Warkworth-based whitebait farm Manaki in a bid to save a native fish species from extinction.

It's the first time an attempt has been made to breed the shortjaw kokopu – a species of whitebait – in captivity.

Council has supplied Manaki with seven shortjaw for the breeding programme.

The shortjaw is the most threatened of the whitebait species. They are only found in two locations in the Auckland region – the Waitakere and the Hunua ranges. Their tiny population in these areas is dwindling, partly due to introduced predators.

Manaki manager Paul Decker says Manaki has successfully bred all the other New Zealand whitebait species and anticipates the company will be able to do the same with the shortjaw.

But he concedes that since the task has never been attempted before, nothing is certain and there's the additional pressure of ensuring the captive shortjaws survive.

“If you take an endangered species out of the wild and it dies on your watch, it's a bit embarrassing – you would be actively participating in the extinction of the species,” Paul says.

Fortunately, the fish appear to be responding well to their new captive environment.

They are being kept in a 1000 litre tank, which is automatically filtered, oxygenated and kept at a low temperature to mimic ideal conditions in the wild.

The fish normally feed on insects blown into the water from trees. At Manaki, they are fed microwaved, dried caterpillars, which Paul says taste just like potato chips.

“They are feeding well. A happy fish is an eating fish.”

Feeding must be carefully controlled. If the fish get too fat, then the females will produce only low-quality eggs.

Paul anticipates the first lot of eggs will start appearing late next month. Given the stress the fish have had to endure, the first batch of eggs may not necessarily hatch live fish, but Paul has high hopes they will do next year.

He says shortjaw kokopu have likely been overlooked as a species worth preserving up until now because the nocturnal fish inhabits freshwater water holes high in the hills. Few people will have ever seen one.

“Whereas the kiwi, the tuatara and the robin are quite visual and people see them as being cute,” he says.

Paul says Council has a strong environmental programme underway, which aims to remove predators and restore habitats for native species.

The ultimate goal of the project will be to release shortjaw back into restored habitats and create self-sustaining populations.

Paul says it's unlikely that shortjaw kokopu will ever be bred for eating because of their relatively small size, shorter lifespan and the limited number of eggs they lay.

Shortjaw kokapu can grow up to 260mm long and weigh up to 0.5kg.  

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