DNA focus of dolphin count

Maui's dolphins are at risk of extinction. Photo / Glenn Jeffrey

Scientists will use DNA profiling for the first time to count the critically endangered Maui dolphins.

The world's smallest and rarest dolphins lived only off the west cost of the North Island coast and the Department of Conservation (DOC) said fewer than 150 were thought to be left.

"Knowing whether the population is increasing or decreasing in number is critical when assessing the effectiveness of the protection currently provided to them," DOC biodiversity programme manager Phil Brown said.

A two-year joint study by Auckland University and the Oregon State University began in February when 26 dolphins were sampled.

The process would be repeated this summer and Mr Brown said when the samples were compared it would produce a population estimate.

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

He said Maui dolphins were inquisitive and would swim to within a metre or two of a boat.

When the dart was fired the gun gave a small "pop" and the dolphin would flinch, shoot off and the dart would pop out but the process did not scare off the dolphins.

"Within a minute the dolphin would be back at the boat. They don't just hightail it and never come back."

Mr Brown said samples were collected from New Plymouth to Bayley's Beach north of the Kaipara Harbour.

He said the earlier genetic samples may have revealed a link to the South Island Hector's dolphins but another possibility was that the samples were captured from Hector's dolphins which were visiting the North Island Maui.

"We are not certain whether this means these two dolphins are recent migrants from the South Island, or whether these Maui dolphins have retained some of the genes from their distant South Island cousins from years ago," Mr Brown said.

- NZPA