Forest and Bird, with scientists, other conservationists and the public, had been lobbying to have set net fishing banned in Taranaki to protect Maui's dolphins, Ms Subedar said.
"If we have any chance of protecting these endangered native dolphins, the Government must immediately expand the set net restrictions to include waters around and south of Taranaki and also protect key foraging areas within harbours along the west coast of the North Island. It's not rocket science."
World Wildlife Fund New Zealand executive director Chris Howe said the death should serve as a wake-up call that current protection measures were insufficient and a ban on set nets in all areas it was known to be or have been was needed to save the species.
"Set nets in Maui's habitat continue to pose an unacceptable risk to these dolphins," Mr Howe said.
"Until we get set nets out of the shallow coastal waters where they live, more Maui's will needlessly get entangled and drown. The species could be extinct within our generation without urgent action."