DNA profiling helps save Maui’s dolphins

For the first time, the Department of Conservation is using DNA profiling in an effort to update population estimates for the critically endangered Maui’s dolphin.

Maui’s dolphin is the world’s smallest and rarest dolphin, and is found only on the west coast of the North Island of New Zealand.

“Knowing whether the population is increasing or decreasing in number is critical when assessing the effectiveness of the protection currently provided to them,” says DOC Biodiversity Programme Manager Phil Brown.

The last population estimate for Maui’s dolphin, carried out by aerial survey in 2005, showed there was likely to be less than 150 Maui’s dolphins remaining.

The two-year study currently underway — a joint project with the University of Auckland — began in February this year. Twenty-six dolphins were sampled, and when sampling is repeated this summer, the results will be compared and a new population estimate created.

“We collect samples using a lightweight veterinary dart — a low-impact method of collecting small skin samples from which DNA is extracted,” says Mr Brown.

Samples were collected from the very north of where Maui’s are found to the very south — from New Plymouth to Bayley’s Beach north of the Kaipara Harbour — which is a wider sampling area than has ever been undertaken before.

While getting an estimate of the number of dolphins left was the main reason for doing the research, a range of other information will also be collected.

One of the most interesting findings so far is that Maui’s dolphins may have greater genetic diversity than previously thought. Samples suggest that two of the dolphins tested had some link to the South Island Hector’s dolphins in their DNA profiles.

Mr Brown said the University of Auckland and Oregon State University are studying these two samples to determine the origin of the Hector’s dolphin DNA.

“We are not certain whether this means these two dolphins are recent migrants from the South Island, or whether these Maui’s dolphins have retained some of the genes from their distant South Island cousins from years ago.”

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