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16 Apr 07
Kiwis of the Sea: New Zealand dolphins under threat
By Jen Riches
Population fragmentation. It doesn't exactly pack the same punch as 'extinction'. But for New Zealand's South Island Hector's dolphin and North Island Maui's dolphin--one of the rarest marine dolphin species in the world--it could be catastrophic.
"Numbers of Hector's and Maui's dolphins are now so low that populations are starting to fragment," explains marine biologist Dr Steve Dawson, associate professor at New Zealand's Otago University.
"As populations shrink you get small groups of dolphins which are isolated from each other and they literally become fewer and further between. Lose one of those surviving groups and you lose a vital link to the next."
Dubbed the 'kiwis of the sea', Hector's dolphin numbers (both North Island and South Island populations) have plummeted from over 26,000 in the 1970s to just over 7,000 today.
Maui's dolphins, a subspecies of the Hector's, are faring even worse and are now critically endangered with a population of just 110 individuals. Without immediate protection, Maui's may become extinct within a generation.
Fragmentation is the path to extinction, according to marine scientists, and for the Maui's in particular, this is a very real possibility.
"These animals don't range very far, so as the distance between groups grows, the chances of those groups interacting, breeding and surviving becomes more remote," says Dr Dawson. "The reality is their future survival is dependent on our actions today."
Close to shore
Maui's dolphins live off the west coast of New Zealand's North Island, and are usually found in isolated pockets within 10km of the shore. During summer they are even closer, moving to within 1.85km (1 nautical mile) of the coast in search of food.
Although found so close to shore, tracking Maui's dolphins by sight remains problematic. Aerial surveys and sound recordings are more reliable methods and are currently being used to find out more about this critically endangered dolphin.
Recent sound recordings of the Maui's dolphin conducted by Dr Dawson and other scientists from the University of Otago are providing new information about the Maui's presence in harbours.
"We now have scientific evidence to support the argument that Maui's really are at risk of drowning in nets being used by fishers in harbours along the North Island's west coast," said WWF-New Zealand marine campaigner Rebecca Bird.
The results will contribute to learning more about the dolphin's" distribution and abundance and use of harbours, and will be used in WWF's advocacy work, which seeks greater protection for the species.
WWF, with help from researchers and Toyota New Zealand, has also developed a WWF Sightings Network in order to learn more about the dolphins' movements from season to season.
Data generated for the network by the public provide vital information that can be used to determine future research and management priorities, and returns responsibility for Maui's back to the community.
"We believe people have an important role to play in saving Hector's and Maui's dolphins," Bird explains. "The information we get from the public tells us where the dolphins are from season to season. At the end of the day, the responsibility for saving these iconic animals lies with all of us."
Returning from the brink
Fishing in coastal areas is seen as the biggest threat to the dolphins, where they become entangled and drown in commercial and recreational set nets, or caught as accidental bycatch in fishing trawlers.
Add to this boat strikes, disturbances from tourism and increasingly polluted waters, and survival for the world's rarest dolphins is a losing battle.
To reverse the trend, WWF has been working to reduce the threats so that the species can return from the brink of extinction.
"Our conservation challenge to the New Zealand government calls for an action plan for the recovery of the species, to address the causes of the dolphins' decline," says WWF-New Zealand Executive Director Chris Howe.
"We envision a future where Hector's and Maui's dolphin numbers increase, where they recover to their natural historic range and where population fragmentation is reduced. That means ending fishing-related bycatch, protecting their habitats and reducing marine pollution."
By law, the New Zealand government is required to protect its native flora and fauna. Although the government has introduced interim protection measures and set net bans are in place in some areas, it has yet to develop a comprehensive action plan for the dolphins' recovery.
"If we are serious about saving the species, we can't deal in half measures," stresses Howe. "We need a total ban on set netting and trawling where the dolphins range. "We still have a chance to save these unique creatures," he adds, "but we have to act now to make sure New Zealand doesn't become the first nation to drive a marine dolphin species to extinction."
Jenny Riches is a Press Officer at WWF-New Zealand.
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