Department of Conservation Aquatic Director Elizabeth Heeg says it is too early to say what caused the deaths of the four dolphins, but DOC is grateful for the actions of the public in reporting them.
The four dead beachcast Hector's dolphin calves were found in the second half of November, with three of them found over the past week.A member of the public found the body of a Hector's dolphin calf on Saturday 27 November, at Marfells Beach in South Marlborough, and reported it to DOC the next day.
On Sunday 28 November, another calf was found decomposing on a beach just north of Hokitika.
The third Hector's dolphin discovery was made on 30 November at Ōkārito on the West Coast. This dolphin, also a calf, was quite fresh, indicating it had likely been found and reported not too long after it died.
Earlier in the month (16 November) a calf was discovered dead near the town of Hector, on the West Coast.
Elizabeth Heeg says three of the bodies of the dead dolphins are being sent to Massey University, Palmerston North, for necropsy in an effort find out how they died.
"From the necropsies done by the Massey team, we can glean really valuable information about these species and the threats they face.
"When people are quick to alert us to discoveries of dead dolphins, however sad, it increases the volume and value of the information we can obtain.
"The people who let us know about these dolphins did exactly the right thing and we're very grateful for that.
"Along with reporting live strandings, the prompt reporting of a dead Hector's dolphin is what we're after from our coastal communities."
Due to the level of decomposition on two of the bodies, they have been frozen and will be examined later in the month. The third was fresh enough to send chilled and is likely to be examined sooner.
Hector's and Māui dolphin bodies are routinely sent to Massey University for necropsy to obtain information such as cause of death (when this can be determined), including examination for disease. Information on the sex, body condition and other biological information is also recorded. The level of decomposition of a dolphin carcass, and whether it has been frozen, are key factors in how much information can be determined.
DOC maintains a database of incidents involving Hector's and Māui dolphins, based on reported events. These include live stranded animals, dolphins found dead on beaches, injured at sea, found floating dead in the ocean, or caught as part of recreational or commercial fishing. This data is shared online, along with any necropsy reports, on a quarterly basis. The next update will be in early February.
Background information
Hector's dolphins are the world's smallest dolphin species, with adults measuring about 1.5m long.
Identifiable through their distinctive round dorsal fins, Hector's dolphins' bodies are grey with black and white markings.
The work to protect both Hector's and Māui dolphins is guided by the Hector's and Māui Dolphins Threat Management Plan.
