There are concerns for the future of the world's rarest marine dolphin as an autopsy on a newborn Maui’s dolphin revealed the presence of the bacterium Brucella, which creates the disease brucellosis. Brucellosis causes abortions and reproductive failures in livestock. The dolphin was born alive but never made it to the surface to take its first breath.

The animal was found at the mouth of the Waikato River in November 2006 and Brucella was identified by DNA methods at the Biosecurity New Zealand Investigation and Diagnostic Centre. This laboratory has previously found evidence of marine strains of Brucella in Hector’s dolphin. Two other Maui’s dolphins found over the past few months were also tested but the Brucella bacteria was not detected. Brucellosis has been diagnosed in a variety of cetacean populations worldwide and while vaccines are available for livestock, there are none for marine mammals.

Bacteria is already present in the Hector’s dolphin population, but it’s not known yet how it is affecting that particular population. All dead Maui’s and Hector’s dolphins found automatically undergo post mortem to determine the cause of their death. Maui's dolphins are generally found along the North West coast of the North Island of New Zealand, between New Plymouth and Dargaville. With only 100 animals left, all individual dolphins are vital for the survival of this population.