Hector’s dolphins still headed for extinction

EXTINCTION THREAT: Hector's dolphins are often caught and killed in gill nets

Fewer than 100 Maui's dolphins remain

September 2011: Measures to protect the world's most endangered marine dolphins against fisheries bycatch are inadequate to prevent their extinction, an international marine conference has been told.

Speaking at the World Conference on Marine Biodiversity in Aberdeen, a conservationist said that since nylon fishing nets came into use in the 1970s, entanglements in gill and trawl nets have decimated the once 30,000 strong population of Hector's dolphins to about a quarter.

The country's North Island population, a separate subspecies known as Maui's dolphins, is down to fewer than 100 individuals, according to Dr Barbara Maas, head of endangered species conservation with NABU International - Foundation for Nature, one of Germany's oldest and largest environmental associations.

With no more than 25 adult females left, Maui's dolphins are perilously close to extinction, Dr Maas told the conference.

Bycatch is decimating the population
Dr Liz Slooten from Otago University and Dr Nick Davies from the Oceanic Fisheries Programme in New Caledonia examined data on commercial gillnetting on the east coast of New Zealand's South Island, the only part of the country for which bycatch levels in this fishery were established by government observers.

‘Our research shows that each year 23 Hector's dolphins drown in commercial gillnets off the east coast of the South Island,' says Dr Slooten. ‘The sustainable limit for this area is about one dolphin a year. This level of bycatch will deplete the population by least a further 14 per cent by 2050.'

But Dr Maas - who has been on the forefront of efforts to protect the species for more than a decade, including as part of New Zealand's Department of Conservation, claims this is only part of the problem.

‘Other fishing methods that are known to kill Hector's dolphins, such as trawling and recreational gillnetting, are not included in these calculations,' said Dr Maas.

Pushed beyond the point of no return
‘Hazards such as pollution, boat strikes, and marine mining are also treated as if they have no effect on dolphin survival or reproduction. Trawl nets are likely to claim as many endangered Hector's dolphins as commercial gillnets. This brings the number of deaths caused by commercial fishing along the east coast of the South Island to 46.

‘An annual loss of this size will wipe out 62 per cent of the population by 2050. Only a scattering of animals will survive, potentially pushing the population beyond the point of no return.'

Dr Maas warns that under current management Hector's dolphins will continue to slide towards extinction.
‘Absolute protection against commercial and recreational gill-netting and trawling is the only way to prevent their demise,' she said.

‘There have been calls for a New Zealand-wide ban on gill and trawl nets in waters up to 100m depth for more than two decades. This could easily be achieved by switching to more selective fishing methods that don't catch dolphins, such as hook and line fishing and fish traps.

‘New Zealand must act now, before it is too late.'