Endangered whitebait species found populating Auckland wetlands

An endemic freshwater fish is causing a big fuss on Waiheke Island.

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The giant kokopu is on the decline nationally. Source: 1 NEWS

The rare giant kokopu, one of five whitebait species in New Zealand, is declining in numbers nationwide, but surprisingly, a small population has been found.

Rob Morton was out pig hunting one evening when he heard a splash in the wetlands.

“I expected to see a pig but when I got closer it was actually a fish,” he says.

The two fish were spawning on the wetlands, something Rob thinks hasn’t been seen before.

“I called up Matt from Auckland Council and he came over to the island a couple days later and sure enough, we found some eggs in the mud on the bank,” he says.

Matt Bloxham, a biodiversity advisor from Auckland Council describes finding the spawning grounds as "gold".

“Now we can really move to protect those areas and some really great work can be done by Forest and Bird and other contractors to protect those areas,” Mr Bloxham says.

While the nocturnal fish can live up to 30 years, there are some major factors contributing to the development of rejuvenating the population.

“Sediment is a huge problem for giant kokopu in freshwater catchments,” Mr Bloxham says.

Unsealed roads close to streams can destroy habitats, with the dust from vehicles landing in the water.

Without proper fencing, livestock can also trample wetlands where the giant kokopu live.

Mr Bloxham and wildlands consultant Nick Goldwater are actively looking for properties on Waiheke Island that hold wetlands or streams.

“We’re asking them to consider putting up more fencing and laying more pest traps,” Mr Goldwater says. 

The giant kokopu lives a remarkable lifecycle - starting as eggs, they develop on land for two months, before relying on storm water to wash them back into a freshwater stream to hatch.

Then as larva they find their way out to sea where they grow and become juveniles.

“This is where thousands of them are prone to being eaten by predators,” says Mr Bloxham. 

Once juveniles, they find their way back to a freshwater stream.

There are five whitebait species in New Zealand, four of which are endangered.

“A lot of attention has historically been on the cute furry, feathery creatures but what people don’t realise is the giant kokopu has the same threat level as the kiwi. These fish are at serious risk of extinction,” says Mr Goldwater. 

The cigar-shaped fish can grow up to 35 centimetres in length, and has golden speckles along its back.

“They’re just stunning to look at. I’ve been waiting all my life to see one,” says Mr Morton. 

The pair advise if do have water on your property and spot one, recognise the surroundings and think about what you could do to make the environment safer.