Welcome return for giant kokopu

DAVID TATE

BACK HOME: After disappearing during the drought, nearly half of the kokopu released into the Nukumea Stream at Orewa have returned.

DAVID TATE

GONE: When Josh Smith, front, and Dr Paul Franklin from NIWA looked in on the native fish in March they had vanished.

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Rare giant kokopu fish which vanished after release into the Nukumea Stream at Orewa have returned.

Thirty native fish were released into the stream at the end of last year as part of a programme by the NZ Transport Agency and Northern Gateway Alliance to mitigate issues associated with the construction of the Northern Gateway Toll Rd on State Highway 1.

But when NIWA freshwater fish scientists went back to check on them in March they were nowhere to be found.

After one of the worst droughts in years the stream level had dropped dramatically

Originally a Mahurangi Technical Institute initiative, the fish were raised at its Warkworth facility for three years from eggs collected from the Waitetuna River.

The fish were then fitted with tiny transponder tags which could be picked up by an antenna in the stream.

It was expected the rare natives would settle into the stream and call it home.

Loss of habitat has seen a big decline in the numbers of the fish. Their larvae drift out to sea and then return to rivers and streams as one of the species that make up whitebait.

The study is a first to see if restocking is possible.

With river levels higher in June, scientists found four of the tagged fish and another seven have since returned. It is hoped more will be found in subsequent checks.

If the trial is successful, there are plans to eventually release up to 1000 of the juvenile fish into the stream.

"It's great news," NIWA's Dr Paul Franklin says.

"The information we are collecting on their movements and habitat will be invaluable for the conservation of giant kokopu in the future."

- © Fairfax NZ News