Five Hector's dolphins have been killed after they were trapped in a commercial set net off the Banks Peninsula in February.
There's believed to be only about 10,000 Hector's dolphins left in the wild.
As a result of the drownings, the Government will review the use of set nets, with an eye toward possibly phasing out their use.
Hector's dolphins are only found in New Zealand and can be identified by their distinctive black and white markings and round dorsal fins. They are one of the world's smallest marine dolphins.
The Māui dolphin are a sub-species of the Hector's dolphin.
The Department of Conservation says set nets pose a "major" risk to Hector's dolphins. Set nets must be removed from the water if dolphins are seen in the area.
An estimated 110-150 dolphins are caught in set nets every year in New Zealand.
The fisher who caught the dolphins reported the incident. According to fishing industry representatives, the fisher "deeply regrets the capture" and immediately stopped set-netting in the area.
Conservation Minister Eugenie Sage says it's not just dolphins being killed by set net use - they also drown seabirds including penguins and terns.
"The needless death of five dolphins in one set net underlines the ongoing problem of set net use in places where highly endangered species like Hector's and Maui dolphins live, and the indiscriminate nature of set nets as a fishing method," Ms Sage said.
South Australia, California and North Carolina have banned set netting to protect sealife.
"Having a serious look at how to best phase out these near invisible and deadly mono-filament gill nets is long overdue," Ms Sage said.
"Fishers can use other methods to catch target species such as butterfish, mullet, rig, and school skark."
Fisheries Inshore New Zealand chief executive Jeremy Helson is calling on the fast-tracking of a review of the Hector's dolphin threat management plan and measures to prevent a repeat of the incident.
The Government will look at:
- Prioritising the development of a new Threat Management Plan for Māui's and Hector's dolphins
- Reviewing the use of set nets in a bid to reduce or phase out their use
- Considering extending the ban on set nets in the Banks Peninsula Marine Mammal Sanctuary further offshore
- Encouraging voluntary closures of certain fisheries to set nets such as those recently put in place by commercial set netters to protect the hoihō/yellow eyed penguin off Southland.
- The role of observers and camera coverage on fishing boats