The Māui's dolphin population is now so low that the death of a female found 20km north of Raglan on Sunday seriously matters.

She was examined at Massey University's veterinary pathology clinic on Wednesday, where it was discovered she was pregnant.

It's a double blow for the endangered species, which produces just one calf every two to four years.

The Department Of Conservation (Doc) is calling on the public to photograph and report any sightings of a Māui's or Hector's dolphin to the emergency hotline.

Sightings help DoC understand exactly where the dolphins are found and where they go.

Māui's dolphins are easy to spot, with a rounded 'Mickey Mouse' dorsal fin rather than a triangular-shaped fin like most dolphins.

The threat management plan is currently being reviewed, and Forest and Bird's Anton Van Helden says authorities need to look at regulating fishing in the area.

"We need to look at how we regulate the fishing in this area, and the by-catch of these animals needs to come down to zero," he said.

"This is a sub-species of Hector's dolphin, and it is on the brink of extinction."

With only 63 of the animals left, any loss is treated as a significant blow.

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