Hector’s dolphins

The problem

Hector’s dolphin is New Zealand’s only endemic cetacean (marine mammal) and is one of the world’s rarest dolphin species. The species is divided into two subspecies, one of which occurs in South Island waters, and the other in the waters off the north-west coast of the North Island.

The South Island Hector’s dolphin is ranked as nationally vulnerable by the Department of Conservation (DOC) and endangered by the World Conservation Union (IUCN). The current population is estimated to number around 7,270 individuals. The North Island Maui’s dolphin, with an estimated population size of 111 individuals, is ranked as nationally critical by DOC and critically endangered by the IUCN.

Hector’s dolphin is an inshore coastal species with a limited home range. Four genetically distinct Hector’s dolphin populations have been identified. These are found on the north-west coast of the North Island (i.e. North Island subspecies), the west coast of the South Island, the east coast of the South Island and the south coast of the South Island.

Dolphins are at risk of becoming entangled in fishing gear. Of the different fishing methods, set net fisheries appear to pose the greatest fishing related risks to Hector’s dolphin populations as the dolphins’ inshore distribution overlaps with commercial and non-commercial set net fisheries. However, there have also been reports of dolphin captures in trawl nets. Hector’s dolphins are threatened by even low levels of mortality due to slow reproduction rates resulting in low potential for population growth.

Current and future management

The Government has put a number of measures in place to reduce the impacts of fishing on Hector’s dolphins.

Commercial and recreational set netting is banned between Maunganui Bluff (north of Dargaville) and Pariokariwa Point (north of New Plymouth), to a distance of four nautical miles offshore. Set netting has also been banned in the Manukau Harbour entrance.

Much of the north west coast is also closed to commercial trawling and Danish seining, out to one nautical mile from the coast. Trawling and Danish seining are also prohibited in defined areas, including: Kawhia Harbour, Aotea Harbour, Raglan Harbour, Manukau Harbour, Kaipara Harbour, Hokianga Harbour, Waikato River Mouth and adjacent seas within 2 nm. The harbours of Herekino and Whangape are also closed to trawling and Danish seining. These closures were not put in place for the purpose of protecting Maui’s dolphins, but nonetheless mean that trawling is prohibited in a substantial portion of the known distribution.

The Banks Peninsula Marine Mammal Sanctuary (1170 km²) allows limited recreational set netting between 1 March and 31 October. Recreational set netting is otherwise prohibited, and there is no commercial set netting allowed within the Sanctuary.

A seasonal closure is in place under the Canterbury set net regulations, where, in addition to the existing Banks Peninsula Marine Mammal Sanctuary, recreational set nets are now banned out to four nautical miles between the Waiau and Waitaki Rivers from 1 October to 31 March of the following year (with the exception of certain reefs).

There are also voluntary measures in place to reduce the impacts of fishing on Hector’s dolphins. There is a long-standing agreement amongst local fishers to not use set nets in the vicinity of Porpoise Bay (Catlins). At Kaikoura, local fishers have agreed to not use set nets near open beaches. Commercial fishers of the Canterbury Bight and Pegasus Bay do not trawl in critical areas for Hector’s dolphin conservation (one nautical mile from shore) and commercial set netters do not fish within four nautical miles of the Canterbury Bight coast from October to January. Commercial fishers have started placing acoustic pingers on their nets and boats to scare dolphins away from the nets and have adopted fishing practices that minimise the likelihood of Hector’s dolphin being caught in nets.

At present, the Department of Conservation and the Ministry of Fisheries are jointly developing a Threat Management Plan to manage the threats to Hector’s dolphins. The Plan will address all known actual and potential threats, including fishing-related mortality (in particular set netting), boat strike, noise, pollution, mining, climate, and tourism impacts. Experts on dolphins and people from all interest groups are involved in the development of the Plan.

Public and government concern over the effect of human induced mortality on Hector’s and Maui’s dolphins has led to the development of a draft Threat Management Plan (TMP) to help protect these species.

Hector's Dolphin Draft Threat Management Plan

Led by the Ministry of Fisheries and the Department of Conservation, the Draft TMP seeks to: 

• Describe the nature and extent of threats to Hectors and Maui’s dolphins, and
• Implement strategies to reduce those threats which are human induced .

The draft TMP builds on material released in a discussion document in May 2007 and incorporates response to that document including feedback gained during regional forums. 

Consultations: Hector's Dolphin Draft Threat Management Plan

The Hector’s dolphin Threat Management Discussion Document was used to provide background information for regional stakeholders, about the current biological status of Hector’s dolphins, documented threats and a range of mitigation measures available to avoid, remedy or mitigate human induced threats to the dolphins.

 Download Hector’s Dolphin Threat Management Discussion Document (PDF 1.9MB)

Relationship with West Coast Marine Protected Area Process

The Government has set up a community, tangata whenua and stakeholder process on the West Coast under the Marine Protected Areas Policy (MPA) to consult on options for marine protection and make recommendations to Ministers.

Rather than a single species focus the MPA policy aims to protect marine and coastal habitats and ecosystems in an integrated way, whereas this Hector’s dolphin Discussion Document is concerned to manage threats to Hector’s dolphins; a single marine species. The West Coast MPA process will not address threats to Hector’s dolphins other than at an ecosystem level.