New Zealand scientists have proved for the first time that Marine Protected Areas are effective in protecting endangered animals.
The findings have come from a 21-year study of Hector's dolphins at a South Island marine sanctuary.
The sanctuary covers 1170 square kilometres off the coast of Christchurch.
Researcher Dr Liz Slooten from Otago University says the dolphins survival increased by 5.4%. However, she says if the reserve is not enlarged, the species is still in danger of extinction.
Each year 23 Hector's dolphins die in commercial gill nets off the east coast of the South Island each year. The sustainable limit is about one death a year.
Conservation group Nabu International says the reserves could also be crucial for the survival of the critically endangered Maui's dolphin, which has only 55 adults surviving, all on the west coast of the North island.