Scientists call for bottom-trawling ban

By SIMON COLLINS

New Zealand is facing pressure to support a worldwide ban on bottom-trawling on the high seas to protect little-known deepwater coral reefs.

Environmentalists say the Government is due to decide in the next month whether to support the ban at this year's United Nations General Assembly meeting starting in late September.

Ten New Zealanders joined 1126 other marine scientists from 69 countries in a call for the ban early this year. One of them, Auckland University of Technology's Dr Steve O'Shea, said New Zealand's offshore coral reefs had already been "devastated" by trawlers, mainly searching for lucrative orange roughy.

A report published by the Deep Sea Conservation Coalition in June named New Zealand as one of 11 leading deepwater fishing nations accounting for 95 per cent of the fish caught in bottom-trawling.

Dr Malcolm Clark, principal deepwater fisheries scientist for the National Institute of Water and Atmospheric Research (Niwa), said researchers had only recently discovered deepwater coral reefs around New Zealand which could be tens of kilometres wide.

"There are shrimps down there that are totally blind, they have no need for eyes. There are corals that are similarly adapted to this quite different environment," he said. "Only a few years ago we didn't even know they were there."

Dr Clark, who will give a public talk on the discoveries at the Auckland Museum tonight, said the deepwater coral species had built reefs up to 10m high on the seafloor, up to 1km below the surface.

"They are different from tropical coral reefs because they do not rely on sunlight," he said.

Whereas tropical corals depend on algae which trap the sun's energy for them, the deepwater corals grow their own feeders which pop out 1mm or so into the sea to catch passing microscopic lifeforms.

Like tropical corals, they grow on solid rock, which is exposed on underwater "seamounts" jutting out of the muddy seafloor.

"There are probably thousands of seamounts in the New Zealand region. We have information on about 800 of them," Dr Clark said.

The corals live for 400 to 500 years and grow about 1.5mm a year. By the time a new layer of coral is completed, the layer underneath will be dead.

Dr Clark said he could not comment on the proposal to ban bottom-trawling, which is opposed by New Zealand's trawling industry. "We are putting information on the table. We haven't got an agenda."

But a Hamilton ecologist who was one of four Niwa experts who signed the call for a ban, Dr Simon Thrush, said deepwater corals were the "rainforests of the sea".

"If you log a radiata pine forest that has a cropping return of 30 to 50 years, that is different from trying to sustainably log a rimu forest on the West Coast that is 500 years old," he said. "People have done studies on deepwater corals and found them to be 1000 or more years old."

A Niwa report found that two kinds of deepsea stony corals ranged from 200 to 6000 years old.

"Those types of ecosystems with those kinds of animal communities are poorly understood and they are under threat around the world," Dr Thrush said.

"I believe that, with the knowledge that scientists have about those systems, it's important to bring that to light, just as it was to bring to light knowledge that DDT was wiping out eagles and birds of prey in Europe in the 1960s."

* Dr Clark speaks on NZ deep ocean topography and biodiversity, tonight, Manaia Room, Auckland Museum, 7.30pm.

Signatories

New Zealanders who signed the call for bottom-trawling ban

Dr Bill Ballantine, Auckland University

Luca Chiaroni, Niwa, Hamilton

Darrin Drumm, Otago University

Anthony Hickey, Auckland University

Dr Carolyn Lundquist, Niwa, Hamilton

Dr Steve O'Shea, AUT

Gabriela Pinto, Auckland University

Dr Juan Sanchez, Niwa, Wellington

Dr Peter Stratford, Otago University

Dr Simon Thrush, Niwa, Hamilton