Experts believe Maui’s dolphin numbers are lower than previously thought and
say the species could be perilously close to being lost forever.
The Conservation Department has been using DNA profiling to count numbers of
the world’s smallest and rarest dolphin, and preliminary results are now being
worked through.
The last population estimate, published in 2005, suggested there were likely
to be 111 dolphins left, but DOC’s Maui’s dolphin recovery group leader Phil
Brown said the results of the latest surveys were likely to show the population
was smaller than that.
“The indications are that there’s probably fewer than 100.”
The dolphins, found only off the North Island’s west coast, most commonly
between Kaipara Harbour and Port Waikato, live for about 20 years.
Most females gave birth to only four to six calves in their lifetime and,
given the slow breeding cycle, Mr Brown said any deaths within the population
outside those caused naturally could have a devastating impact.
“They are so perilously close to extinction that taking out one … is enough
in the models to push them to extinction.”
Sharks are natural predators for the dolphins, but severe storms could also
be dangerous for juveniles. “These guys are down to very, very low numbers. This
is where chance starts playing a part.”
Set and trawl nets present risks to the dolphins, but none have been killed
in nets since restrictions were introduced in 2003.
Mr Brown said the dolphins were now reasonably well protected, but those that
swam around the far reaches of their habitat were still at risk.
However, the researchers also uncovered information that gave them hope, and
presented perhaps the best chance of survival for the species.
Last summer, two Hector’s dolphins were found to have travelled from the
South Island to the Maui’s habitat in the North Island. Researchers found one
Hector’s dolphin in the same area this summer.
If the two species were to breed, the Maui’s population could have a chance
of survival. Hector’s dolphins are also endangered, with an estimated 7000
around the South Island.
WWF marine advocate Bob Zuur said the Government had reduced the threats to
Maui’s dolphins by introducing the fishing restrictions.
However, he warned that the potential for threats remained through the
possibility for seabed mining.
He hoped that, should future ironsands mining applications be considered for
the North Island’s west coast, the risk that such activity presented to the
dolphins would be taken into account.
were currently travelling through dangerous waters without set net or trawl
restrictions to reach North Island waters.
“We need to make sure the animals that are moving are not at risk. Currently
they are.”
Source: Stuff.co.nz