Hector's dolphins: on the edge

New Zealand is home to the world’s smallest and rarest marine dolphin – the Hector’s dolphin.

In the 1970s they numbered between 21,000 and 29,000. Today, fewer than 8000 dolphins remain, with sub-populations fragmented to a degree that threatens their survival. Hector’s dolphins in the North Island and the South Island have been separated to such a degree so that the species has been divided into genetically distinct sub-species:

Maui’s dolphin SI Hector's dolphin

Both are listed on the IUCN’s (World Conservation Union) Red List of threatened species, with Maui’s dolphin listed as 'Critically Endangered', due to an estimated population of just 111 individuals.

Hector's dolphins are slow breeders, which puts them at particular risk from human induced mortality.

Threats to Hector’s dolphin

Set nets, used in both commercial and recreational set net fishing, are the single most significant human threat to the survival of Hector's dolphins, responsible for over 60 per cent of all known causes of reported deaths. These nets are used to catch fish in coastal waters where Hector's dolphins live - the dolphins get entangled in these nets and drown. Set nets are indiscriminate, killing a wide range of non-target fish, other dolphins, seals and seabirds. They are banned or heavily regulated in many countries.

A study by NIWA, with the Ministry of Fisheries, fishing industry and academic researchers, shows that an estimated 110-150 Hector’s dolphins are killed in commercial set nets every year. Deaths caused by recreational set netting or other fishing methods were not included in the research. The study also showed that without change to fishing, Hector’s dolphins are more likely to decline than increase. The decline could be substantial and to the level where the extinction risk of some populations is very high. But if set netting is banned, the probability of population growth will increase significantly.

Trawlers are also a threat. On 3 April 2006, 3 Hectors dolphins were caught by one single commercial trawl vessel around the Marlborough Sounds. Off the west coast of the North Island, where Maui’s dolphins live, 22 common dolphins were caught and killed by 4 trawl vessels in December 2007.

Other human-induced threats – Cray pot entanglement, boat strikes, drift netting, tourism, marine farming, pollution, seabed mining (for sand, iron and gold) and construction.

What is being done?

In May 2008 the Government announced new measures to protect Hector’s and Maui’s dolphins. The package of regulations recognises the impact of set net fishing as the greatest threat to the dolphins but also seeks to address a number of other threats:

Fishing threats
Set net fishing is banned within 4 nautical miles in the South Island (except West Coast) and 7 nautical miles in the North Island. These rules apply in most regions inhabited by Hector’s dolphins:

West coast North Island (Maui's dolphin) - Maunganui Bluffs to Pariokariwa Point
East coast of South Island – Marlborough Sounds to the Catlins
South coast of South Island – Te Waewae Bay to the Catlins
West coast South Island – Cape Farewell to Fiordland

Trawling is banned within 2 nautical miles in all regions (except West Coast South Island) and within 4 nautical miles in core Maui’s dolphin habitat (Manukau to Port Waikato).

Drift nets (used only around Port Waikato) are also now banned.

With an extra $6 million over the next three years for observers on all commercial fishing boats within the dolphins’ range, the Government has shown its commitment to finding out the number of dolphins caught in areas left unprotected.

Other threats
Other threats are due to be regulated within 4 new Marine Mammal Sanctuaries and within the existing Banks Peninsula Marine Mammal Sanctuary, which will be extended.

The protection is not as comprehensive as called for by Forest & Bird. but the new measures are nevertheless a very significant step forward for Hector’s and Maui’s dolphins.

What’s missing?

North Island – Maui’s dolphins
Maui’s dolphins are still unprotected:

South of Pariokariwa Point - around Taranaki.
Inside harbours - while the added protection for Maui’s dolphins in harbour entrances is welcomed, most of the harbour habitat is still left unprotected.
Offshore outside the 7 nautical mile set net ban and particularly the 2-4 nautical mile trawl ban.

Maui’s dolphins are on the brink of extinction. We cannot afford to lose a single dolphin to human activities. The new measures are an improvement but there is still an unacceptable level of risk.

South Island
Hector’s dolphins are still unprotected:

Off the West Coast. There is no trawl ban and recreational set netting is banned out to just 2 nautical miles and commercial set netting is banned only between December 1 and February 28.

About 70 per cent of Hector’s dolphins live in waters off the West Coast. Of all Hector’s deaths reported to the Conservation Department since 2000, 41 per cent are from the South Island West Coast. And 39 per cent of all known deaths caused by set nets reported since 2000 are from this region.

Off Banks Peninsula beyond 4 nautical miles from shore (despite extensive research data showing their distribution extends to 100m water depth or 20 nautical miles).
Inside the Banks Peninsula Marine Mammal Sanctuary where flounder nets are still used.
In waters around the top of the South Island (from Farewell Spit to Cape Jackson in the Marlborough Sounds) and in Cook Strait.

What You Can Do

Join Forest and Bird to support this campaign
Make a donation to our Hector's dolphins appeal
Email the Minister of Fisheries (jim.anderton@parliament.govt.nz) and Minister of Conservation (steve.chadwick@parliament.govt.nz) or write to them (Parliament Buildings, Wellington - freepost) congratulating them on the new regulations and calling for extensions where dolphins are still unprotected.
Make a submission in support of the new Marine Mammal Sanctuaries.
Email or write to your local MP and ask them to support the new Marine Mammal Sanctuaries and extend protection where needed.
If you see a North Island Hector's dolphin please report your sighting. Call 0800 4 MAUIS (462 847), fill out a flyer (found at local stores and information centres), or visit www.mauisdolphin.org.nz for more information.
Download our Disappearing Hector's Dolphin Desktop Image - Don't let this be the last time you see them! Click here for JPEG

More information on this site

Photograph by Steve Dawson/NZ Whale & Dolphin Trust
This page was updated on 9 June, 2008