NZ dolphin survival boosted by Marine Protected Area

Hector's dolphins living off the

coast of Christchurch, New Zealand have benefitted from the area's special

designation, say scientists.

Researchers studied the animals, one of the world's most endangered species

of dolphin, for 21 years.

Their results show that the survival rate of the dolphins has increased by

5.4% since the Marine Protection Area (MPA) was declared.

The findings are published in the Journal of Applied Ecology.

"This is the first evidence that Marine Protected Areas can be effective for

marine mammals. We found a significant improvement in the survival rate," said

Dr Liz Slooten from the University of Otago who undertook the research.

In 1988 the Banks Peninsula Marine Mammal Sanctuary was established in the

hope that resident dolphins would be protected from fatalities associated with

the gillnet and trawling activities of the fishing industry.

A team of ecologists conducted regular photo identification of the dolphins

for 21 years, starting two years before the area was officially protected.

"We can identify individual dolphins from their battle

scars - which range from small nicks out of the dorsal fin to major scarring

following shark attacks," explained Dr Slooten.

The researchers used the photographs to create a population model; with this

they were able to analyse how the animals had fared over two decades.

"Estimating population changes in marine mammals is challenging, often

requiring many years of research to produce data accurate enough to detect these

kinds of biological changes," said Dr Slooten.

"It seems to take a long time for a dolphin population to respond to

protection, and therefore a long-term study to detect [any] improvement."

'Not safe yet'

The teams models suggested that the dolphins' survival rate had increased by

5.4% - a positive result but not what the team had expected.

"At first, we were surprised that the survival rates had not increased

further," said Dr Slooten, "Once the Banks Peninsula area was protected, we had

expected the problem to be solved and the population to be healthy and

recovering."

• Hector's dolphins are one of the world's smallest species, reaching up to1.5m long
• They have a characteristic black dorsal fin, which, researchers have noted,resembles Mickey Mouse's ear
• Fewer than 7,500 animals remain in the wild

The team found that the dolphins did not spend the whole

year in the protected area, which reached four nautical miles offshore.

In the winter, more than half the dolphins were found up to 16 nautical miles

outside of the MPA.

"The dolphins don't care how far offshore they are, their distribution

relates to water depth," Dr Slooten explained.

The New Zealand government is now considering whether to extend MPAs where

Hector's dolphins are found.

"The good news is that the situation has improved. The population was doing a

nose-dive, declining at 6% per year, and now it's only declining slowly [at]

about 1% per year," said Dr Slooten.

"The bad news is that the protected area is still too small. It would need to

be extended further offshore to allow the population to stop declining and

better still to grow and recover towards its original population size."

"The MPA hasn't quite yet 'saved' the dolphins but it's been a major step in

the right direction."