My Account
New Zealand’s largest and rarest whitebait species was given a helping hand to re-establish in the wild on July 14 when 140 adult fish were released into a stream in Tawharanui Regional Park.
Paul Decker, of Warkworth whitebait breeder Manaki, says what the average consumer of a whitebait fritter doesn’t know is that whitebait can grow up to 2.5kg as adult fish and live for 30 years.
“While the fertilised eggs can only develop in freshwater, once hatched the fry of these five native fish species immediately get swept out to sea, grow into whitebait and return to spawn up rivers and streams,” Paul says. “But if the juveniles can’t sense the pheromones of their own species they will not go up the waterways. This is one of the reasons whitebait catches have been declining in the wild. As adult populations are decimated inland, more freshwater courses are not seeing the whitebait runs they once had.”
The joint project between Manaki and its new owners Tahu-Whoa Group Holdings, Ngati Manuhiri, Auckland Council and NIWA follows the release last year of 10,000 juvenile giant kokopu (Galaxias argenteus) in two of the park’s main waterways – the largest reintroduction of whitebait in New Zealand.
Giant kokopu disappeared from Tawharanui around 30 years ago following the construction of a dam to create a pond in the lower reaches of Waikokowhai Stream. But restoration efforts since have seen it returned to an environment that scientists believe can now provide the habitat giant kokopu need. Fish from last year’s release have been found at Tawharanui.
The aim is to establish self-sustaining populations of the native fish throughout New Zealand and to support its conservation. The Tawharanui release is part of a pilot project that will ultimately see tens of thousands of these native fish released into the Waikato.
Richard Ebbet releasing juvenile kokopu into Waikokowhai Stream.
NIWA principal scientist Dr Cindy Baker and staff have installed antennae at the dam exit, in the dam itself and in the stream that feeds into the dam which will pick up the movements of the giant kokopu.
“We want to understand how fish use the environment – how much time they’re spending in the dam, compared to in the stream, whether they’re adapting to this habitat or whether they leave the system,” Dr Baker says.
