Releasing of shortjaw kōkopu into the Castle Stream in the Huia catchment. About 1000 kōkopu were released at five sites in the catchment area. Photo: RNZ / Lucy Xia
About 1000 of New Zealand's rarest whitebait species - the shortjaw kōkopu - have been released into streams in Auckland's Waitākere Ranges.
They were released on Thursday as part of a conservation project to protect the future of kōkopu in the wild.
The breeding project is a collaboration between breeder Manāaki Technologies and partners including Auckland Council, Watercare, local iwi Te Kawerau ā Maki and the National Institute of Water and Atmospheric Research (NIWA).
Auckland is home to a handful of populations of shortjaw kōkopu, and all but two are found in the Waitākere Ranges.
In 2019, Manāaki Technologies captured seven adult kōkopu from the Waitākere Ranges and has since bred about 1000 babies in captivity in Warkworth.
Rare whitebait species released into Auckland streams
Today, dozens of conservation staff, rangers and members of Te Kawerau ā Maki trekked the ranges to bring the baby kōkopu into the streams feeding into the Upper Huia Reservoir.
Auckland Council senior regional freshwater advisor Matt Bloxham said the project aims to broaden the resilience and distribution of the species in the Waitākere Ranges.
"Boosting the population of these fish is important to their survival and to the ecosystem.
"It is no longer possible for the fish to reach these catchments naturally because of the presence of the reservoirs' dam walls, once repatriated, the recovery becomes easier as their whole life stages are retained in the fresh water, rather than being split between ocean and fresh water.
"And they are better buffered against major weather events as they are less likely to be displaced," he said.
Shortjaw kōkopu in bags, carried by rangers and conservation staff. Photo: RNZ / Lucy Xia
Paul Decker from Manāaki Technologies said the project is critical to the future survival of the species.
"The species is in serious decline, endangered, so without this type of intervention, they could become extinct, quite frankly," he said.
Edward Ashby of Te Kawerau ā Maki was well aware of how vulnerable kōkupu habitats could be in the face of extreme weather after last years' storms.
"There were only four breeding areas in the Waitākere, for the local population, and we lost one of those during Cyclone Gabrielle, it blew out the Marawhara stream and took out the entire population.
"So what we're doing today is basically like Noah's Ark in the Waitākere Ranges for this tohu, it's really important," he said.
Shortjaw kōkopu were first loaded onto boats to be transported to the top of the dam, then taken in bags by conservation staff who trekked the ranges to release the fish into the streams. Photo: RNZ / Lucy Xia
Ashby said for his iwi, who whakapapa to the Waitākere Ranges area, restoring the kōkopu population here is an important act of kaitiakitanga.
"For our people, this is progress, this is resilience and this is rebuilding our tikanga, our taonga, and our heartland, it's all part of it," he said.
Auckland Council said the project will be monitored for several years to assess how well the species adapt to their new home.
Decker said it was expected that at least 50 percent of the baby kōkopu released today will survive and continue to breed in the freshwater environment in the Huia catchment.
He said the kōkopu there could be reintroduced to other areas in New Zealand in the future.