Giant kokopu to be reintroduced to streams

A two year old 'Giant Kokopu' and the smaller one year old Banded Kokopu. File photo / Greg Bowker

Scientists from the National Institute of Water and Atmospheric Research (Niwa) and the Mahurangi Technical Institute (MTI) have been catching and tagging farmed rare giant kokopu, which in their infancy make up part of the group known as whitebait, to reintroduce the species to Auckland waterways.

The aim is to repopulate a stream in Orewa, 40km north of Auckland, with giant kokopu.

Niwa has implanted the fish with tiny transponder tags (PIT tags).

Each tag has a unique ID, so when the tagged fish are introduced to the stream Niwa will be able to identify each fish separately as they pass by the antennae positioned in the stream.

Dr Paul Franklin from Niwa said it was the first controlled trial in New Zealand that tested whether native fish could be successfully stocked into a stream.

"By tagging the fish we are able to monitor how well they survive and where they choose to live."

The fish to be used for the trial have been hatched and reared in tanks at MTI from eggs originally collected from the Waitetuna River in the Waikato.

In the initial trial, about 30 adult giant kokopu will be released into the stream.

They will be monitored to see if the fish survive and breed and whether there is any impact on the fish and aquatic insects which already live in the stream.

If the trial is successful 500 lots of 1000 juvenile giant kokopu will be released into the stream to combat the declining population.

- NZPA