People are being urged to keep an eye out for Hector's Dolphins along the northern coastlines of the South Island this summer.
Hector's Dolphins Photo: Supplied
Hector's Dolphins were once found all along the coast of the South Island, but they are now considered nationally vulnerable and their population is estimated to be about 15,000.
Their largest populations are found in three places - on the West Coast, the south coast near Bluff, and the east coast from Otago to Marlborough.
Department of Conservation marine ecosystems manager Kirstie Knowles said there was particular interest in sightings of Hector's dolphins around the northern South Island, because little was known about the populations that live and range there.
She said those in the Marlborough Sounds, Golden Bay and Tasman Bay should keep their eyes peeled for the Hector's rounded dorsal fins and the distinctive grey and black markings.
Hector's Dolphin Photo: AFP
"One of the easy ways to spot a Hector's Dolphin is that they are the only ones in our waters that have got a Mickey Mouse or rounded dorsel fin, so if you see a pointed dorsal fin that's not the one we are looking for."
One of the smallest dolphin species in the world, Hector's dolphins face threats from fishing, toxoplasmosis, boat strike and human activity on and in the ocean.
Knowles said sightings helped to inform marine mammal protection.
"The more information we've got, the more likely we can put in some really good measures to protect them.
Knowles said while sightings of live animals were important, the Department of Conservation was just as keen to get reports of dead dolphins in order to examine the cause of death, their disease status, and their distribution.
Anyone who sees a Hector's dolphin is urged to take a photograph and pass it on to DOC via a social media channel, or through their online form.