The Department of Conservation (DOC) spent nearly half a million dollars on an operation to kill one stoat.

In August 2022 a male stoat was identified on Chalky Island/Te Kākahu-O-Tamatea, in Fiordland which has been predator-free since 1999.

Select committee documents show from the time the animal was detected to its capture eight months later DOC spent $483,260.

These include costs such as incident management team costs, staff time, conservation dog handlers, helicopter and boat expenses.

The Government agency spent just over another $210,000 on ensuring the island was pest free by installing surveillance systems and doing biosecurity planning.

In the documents DOC explained that had the stoat not been caught it could have killed Kākāpō chicks, nationally endangered Ted Te Kākahu skinks and Little Spotted Kiwi chicks.

Auckland University Professor of Conservation Biology, James Russell told RNZ the fact Kākāpō have been reintroduced to the island makes it a "precious place."

"That isolation that has protected the birds is also what makes some of these operations so expensive such as doing a predator incursion response."

Russell said he supported DOC's decision to spend the money on the stoat eradication.

"We have to decide, do we want to keep investing in this and push through these reinvasions and hopefully work towards a predator free New Zealand or will we just kind of draw the line and say we're not willing to spend any more money on these predator incursion responses."

He said islands around the country have seen similar stoat incursions.

"On Rangitoto and Motutapu Islands in the Hauraki Gulf they had no less than four stoat incursions over a year in 2021."

Russell said the animal can swim or hitchhike on peoples' boats.

He said half a million dollars does sound like a lot of money but people should remember that DOC manages 33 percent of the country on half a percent of the government's budget.

"When we are looking at some of the challenges and the responsibilities we have to our native birds and reptiles of New Zealand I think we really should feel that DOC's pretty hard done by."

Russell told RNZ with government departments facing restructures they should be trying to help DOC as much as possible.

The Conservation Minister has been approached for comment.

[4 APR: The Southland Conservation Board came out in support of DOC's efforts including the capture of Chalky Island's rogue stoat which they called valiant, and said should be applauded.

They said Chalky Island was at one of the most remote corners of Fiordland, accessible only by boat or helicopter, and its very isolation underpined its suitability as a sanctuary island for some of our most endangered native bird species.

Even a single stoat can imperil the survival of a species, they said, and the extinction of several species of native birds is believed to be due to stoat predation.]

Reproduced with permission