Small dolphin, big problem

What is required to save the Maui's dolphin, or even if it can be saved, is uncertain. Photo from NZ Herald.
What is required to save the Maui's dolphin, or even if it can be saved, is uncertain. Photo from NZ Herald.
New measures to protect Maui's dolphins suggest the Government is responding to international fears for the diminutive dolphin found only in New Zealand waters. But is it too little, too late? Geoff Cumming, of the NZ Herald reports.

If the world's most endangered dolphin has any awareness of its plight, it would do well to make itself known to the Taranaki fishing fleet right now.

Since July, the five set-net fishing boats out of New Plymouth have been barred from fishing within two nautical miles of shore, where the rig and blue warehou they target are most abundant. To fish further out - between two and seven nautical miles - they must have observers on board who record in their log books every 15 minutes what they have seen.

At the time of writing, they had covered 4540 nautical miles during 168 days at sea both inside and outside the restricted area - and the number of Maui's dolphin sightings remains a big, fat zero.

But marine scientists want fishing restrictions extended even further and Primary Industries Minister David Carter is about to decide whether to retain the interim measures or to ban gill-net fishing out to four nautical miles - arguably triggering extinction for the region's fishing industry.

The options are outlined in a review of the Threat Management Plan for Hector's and Maui's dolphins, for which consultation closes on Monday.

If the fishermen are right and there are no Maui's dolphins off Taranaki, what will the measures achieve?

It's not just a handful of fishermen, their crew and families whose livelihoods are at stake. New Plymouth has two fish processors employing a further 30 people. The impact of the interim restrictions on catches has already forced one to lay off staff.

Their jobs might be a small price to pay for saving an endemic (found only in New Zealand waters) dolphin, not least in sparing the blow to our clean, green image that extinction will bring. But if fishermen, marine scientists and conservationists agree on one thing, it is that the latest measures will not save the dolphins.

Most scientists on a risk assessment panel that informed the review agreed the extent of the dolphins' range is Wanganui, and wanted fishing restrictions extended that far south.

The Department of Conservation wanted the interim Taranaki ban to go out to seven nautical miles, in line with restrictions introduced in 2008 off Auckland and Waikato (as far south as Pariokariwa Pt).

International agencies including the International Whaling Commission support a ban on set nets and trawlers to the 100m depth contour. But the Ministry of Primary Industries - in charge of the fishing options in the review - gives Carter the choice of sticking with the two nautical mile ban as far south as Hawera or extending it to four nautical miles.

The fishermen say any restrictions are pointless south of Pariokariwa Pt because the dolphins are not there. Keith Mawson, of processor Egmont Seafoods, says for the past decade targeting fishing has been a soft option rather than funding research into the Maui's numbers, location and health.

"We should be able to fish our historical grounds until there's evidence that there are Maui's dolphins in this area.

"There are guys who've been fishing for 35 or 40 years and they've never seen one." But the industry's stance was not helped in January, when fisherman Ian McDougall killed a dolphin while gill-netting off Cape Egmont.

We will never know whether it was a Hector's or a Maui's - he threw it overboard, fearing prosecution under the Wildlife Act for having an endangered species in his possession. But he reported the bycatch and MPI concluded it was most likely a Maui's.

Found only in New Zealand waters, the threatened Hector's dolphin is the world's smallest, with its critically endangered sub-species, the Maui's, growing to no more than 1.7m.

The Maui's evolution as a sub-species stems from its isolation from South Island Hector's populations off northwest Nelson, Banks Peninsula and the bottom of the South Island.

They prefer coastal shallows, harbours and estuaries, finding their way in turbid inshore waters using ultrasound, but they have trouble picking up modern nylon gill nets.

Their plight was highlighted in the early 1990s when University of Otago researchers Liz Slooten and Steve Dawson found large numbers were dying in gill nets off Banks Peninsula.

Alarmingly, research estimates the adult Maui's population is about 55, with fewer than 20 females of breeding age. This is half the estimate from a previous survey.

The Doc-funded research by University of Auckland scientists over consecutive summers also challenged assumptions that the dolphins do not travel far, revealing one had moved 80km.

Then came confirmed sightings of Hector's dolphins in the area - two live and two washed ashore. Their presence has excited scientists by raising the prospect that the Hector's could provide a lifeline for the Maui's through interbreeding.

Fishers say the Hector's are occasional strays and argue that any interbreeding would result in a hybrid, not a Maui's.

Though genetic sampling has confirmed the Maui's were once as far south as Kapiti and Wellington harbour, they are now thought largely confined to the coast between the Kaipara and Kawhia harbours and concentrated in a 40 nautical mile stretch from Manukau Harbour to south of Port Waikato.

The Prime Minister's chief science adviser, Sir Peter Gluckman, is one scientist who has publicly wondered whether the dolphin is beyond the tipping point for species survival.

But cetacean experts on the risk assessment panel concluded the Maui's was not beyond salvation, pointing to the recovery of southern right whales and Antarctic blue whales from quite low numbers once protections were in place.

"Saving Maui's is quite simple," Slooten says.

"It simply consists of stopping an impact. There is no need to pour millions of dollars in. All we need to say is, if you want to fish in a critically endangered habitat please use dolphin-safe methods."

Sightings of Hector's dolphins in the area have raised hopes.

Environmental groups and some scientists want a "protection corridor" created between Taranaki and northwest Nelson to increase the chances that Hector's dolphins may move north successfully.

"Fifty-five adults is really low," says Slooten.

"They don't stand much chance unless many animals come in from the South Island.

It's better to have a slightly weakened Maui's dolphin gene pool than to preside over the extinction of an entire population."

Other scientists agree interbreeding would not erase the genetic differences that make the Maui's distinct. In fact, increased genetic diversity is what the tiny population desperately needs.

Dr Slooten says there is not time to obtain the level of proof needed to quieten the fishermen.

"We've got to make a precautionary decision and this seems to be lost on MPI." However, New Zealand was the only country to oppose an International Union for the Conservation of Nature resolution calling for gill nets and trawling to be banned to the 100m depth contour in areas of Maui's and Hector's distribution.

Doc representatives at the meeting bowed to Ministry of Primary Industries advice that such an extension lacked scientific evidence.

MPI is in charge of the fisheries recommendations for the current review.

Latest research has thrown a new element into the mix.

Massey University pathobiologist Dr Wendi Roe has established a parasite traced to cats as the prime cause of death in seven of 28 beached Hector's-type dolphins she autopsied, including two out of three Maui's dolphins.

The fishing industry has seized on the findings to back its argument that, instead of targeting fishing, urgent research is needed into the range, health and abundance of the dolphins so steps can be taken to rebuild the population.