Department of Conservation's threats report 'flawed system', say marine advocates

Monday, 27 May 2019

WWF NZ researcher Amanda Leathers explains why Hector's and Māui dolphin are on the brink of extinction. (First published May 9, 2019)

Threat levels to New Zealand marine species are underestimated, optimistic and flawed, organisations have warned.

The marine mammal threat report released by the Department of Conservation (DOC) on Sunday downgraded the Hector's dolphins status from 'endangered' to 'vulnerable', alongside a raft of other changes.

But DOC's reported aerial sightings of the dolphins didn't mean threats to the dolphins had lessened, Forest & Bird marine advocate Anton van Helden said.

Between 10,000 to15,000 Hector's dolphin remain, down from 29,000 in the last 45 years.

'They range further than previously thought, and so are potentially exposed to other risks.'

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Between 10,000 to 15,000 Hector's dolphin`s remain, down from 29,000 in the last 45 years.

The new threat status is based on a greater population of the dolphins in the South Island than previously known rather than any actual improvement in the species.

'Some of these populations are very small, their ranges overlap with human threats such as set nets and trawl fisheries, and they are increasingly vulnerable to disease.'

It was also alarming that Māui dolphins remained critically endangered, he said.

'We need to reduce human threats to as close to zero as possible for Māui dolphins to have any real chance of survival.'

The report listed 30 species where there was not enough data to make an assessment.

'They should really be considered 'assumed threatened',' van Helden said.

Sea Shepherd NZ managing director Michael Lawry said this year 12 Hector's dolphins were killed in trawl and gillnets in the Canterbury region alone.

They had seen increasing fragmentation in Hector's subpopulations in the South Island, with some populations gone forever, Lawry said.

In Golden Bay there were no sightings in the summer, and one sighting of three dolphins in winter, he said.

'[It] does not bode well for the upcoming Hector's and Maui Threat Management Plan.

'As scientists continue to disagree on threats to our endemic dolphin we hope the two species aren't lost in the noise.'

Marine advocate Katrina Goddard was critical of the improved status for sea lions. 'There has been no recovery for sea lions. It's optimistic to say they're even stable.

'The latest pup estimate was lower than last year. The threats haven't changed … this is an illustration of how flawed the [DOC] assessment criteria are.'

DOC marine biologist Dave Lundquist said the threat criteria was not flawed.

Panelists agreed there were gaps in data, and data deficient species shouldn't be treated as if they're not threatened, Lundquist said.

Research on Hector's dolphins was a series of aerial surveys conducted by the Cawthron Institute, he said.

Their estimate of 15,000 in the South Island was sufficient for the panel to improve the dolphin status, he said.

'We based our assessment on that number with confidence.'