Draft Threat Management Plan for Hector’s dolphin

29 August 2007

Conservation Minister Chris Carter today released the draft Hector’s Dolphin Threat Management Plan for public consultation at Willow Park Primary School, Northcote, Auckland.

“Hector’s and Maui’s dolphin are a national taonga we cannot afford to lose,” Chris Carter said. “Their future is grim unless impacts on the species are managed. The Maui subspecies is now down to just 111 individuals, making it the world’s rarest marine dolphin.”

The draft plan was developed by the Ministry of Fisheries and the Department of Conservation and builds on discussions of the range of threats facing the dolphins.

Options include consideration of four new marine mammal sanctuaries, extension of an existing sanctuary, and managing non-fishing-related issues, such as marine tourism.

Fisheries Minister Jim Anderton said measures were already in place to reduce the effects of fishing on the dolphins but concerns remained.

“We are consulting to determine whether additional measures are necessary to protect the dolphins and, if so, what those might be. The discussion document canvasses a wide range of potential measures. We will take whatever steps are necessary.

“Input from stakeholders will provide important information. The Ministry of Fisheries has contracted an independent research provider to gather information on the social, cultural and economic impacts of any further threat management measures,” Jim Anderton said.

The draft plan is now open for public consultation. Submissions close on 24 October 2007. Copies are available here >

At the end of the consultation period, advice will be prepared for the Ministers. A decision is expected in November, in time for any new management measures to be in place before Christmas.

BACKGROUND

At 1.4m long, Maui’s dolphin would fit into an average bathtub while Hector’s is even smaller, making it the world’s smallest marine dolphin. The rounded dorsal fin is unique among all 40 species of dolphin and porpoise. Hector’s live close to shore and are short lived (20 years). Over a lifetime a female will only produce a handful of calves. Such a low reproduction rate means Hector’s and Maui dolphin populations will be threatened by only a few more deaths each year than would occur naturally.

Fishing threats to Hector’s dolphins

Set netting is the biggest known threat to Hector’s dolphins. When nets are set in the water to catch fish, the dolphins occasionally swim into them and become entangled.

Inshore trawling occasionally catches Hector’s dolphins; and there have also been a few occurrences of these dolphins becoming entangled in rock lobster pot lines in the Nelson/Marlborough region.

Another fishing threat is lost nets drifting in the water. This is considered a particular threat around the Waikato River. Fishers use drift nets to target mullet in the river’s lower reaches, and there is a danger that lost nets may wash downstream into the sea where Maui dolphins live.

Current management of fishing threats

The Government has put a number of measures in place around New Zealand to reduce the threat of fishing to Hector’s dolphins, including in the South Island:

• A Marine Mammal Sanctuary around Banks Peninsula
• A seasonal amateur set net ban between the Waiau and Waitaki Rivers (from 1 October to 31 March, out to four nautical miles from shore)
• A requirement for amateur fishers to stay with their nets when fishing at both Te Waewae Bay and Kaikoura (between the Waiau and Clarence Rivers, from 1 October to 31 March)

To protect Maui’s dolphins in the North Island, commercial and amateur set netting has been 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.

Other human-induced threats to Hector’s dolphins

Other human-induced threats to Hector’s dolphins being investigated include marine tourism, vessel traffic, pollution, sedimentation, oil spills, plastic bags, marine farming, construction and mining, coastal development and climate change.

New proposed measures

The draft Threat Management Plan recommends a range of potential options for reducing impacts of human activities on Hector’s and Maui dolphins.

A range of options has been put together for each of the four dolphin populations:

• North Island west coast (Maui Dolphin) 
• East coast of the South Island (Hector’s Dolphin) 
• West coast of the South Island (Hector’s Dolphin) 
• South coast of the South Island (Hector’s Dolphin)