SCIENCE: Trawlers ‘Bulldozing’ Sea Mountains, Say Researchers

By Stephen Leahy Reprint | | Print |

Stephen Leahy

BROOKLIN, Canada, Aug 29 2003 (IPS) - Scientists are warning that the drop in coastal fish stocks worldwide has pushed fishing fleets into deeper waters in search of rich undersea hills called seamounts, where hundreds of new species have been discovered in recent years.

Such harvesting has left these hills, which can rise 1,000 m above ocean floors, 95 percent bare in certain regions, they add.

"The United Nations needs to place an absolute ban on fishing unexploded seamounts, especially those in international waters," says Ransom Myers, a Canadian fisheries biologist at Dalhousie University in Nova Scotia province.

Volcanic in origin, seamounts are found around the world but are especially abundant in the Pacific Ocean, numbering perhaps 30,000. Described as oases of the deep seas, they are generally covered with deep-sea coral and are home to many unique species.

But they also sometimes attract other ocean life, including food fish that are in high demand in Europe, Japan and North America, such as orange roughy, alfonsino and deep-water red fish. And many wide-ranging species – tuna, sharks and even seabirds – are believed to frequent the areas as they travel the oceans.

"We’re convinced that seamounts are a very important part of the ocean’s ecosystem," Sabine Christiensen of the World Wildlife Fund (Germany) told IPS.

Deep ocean trawlers use sophisticated equipment to find seamounts, and their heavy bottom-dragging nets destroy coral and other species that are the very basis of the areas’ biological productivity. Within a year or two, little is left and it takes many years for them to recover, if ever, said Myers in an interview.

Over fishing has been blamed for a worldwide decline in fish stocks.

”Some marine species are on the brink of extinction and if we don’t make major changes there will be little left in the ocean but plankton,” said Daniel Pauly, a leading fisheries expert based in Canada, in a previous interview with IPS.

Pauly, who worked for many years at the International Centre for Living Aquatic Resource Management (ICLARM) in the Philippines, believes that fishing should be banned in up to one-half of the world’s oceans for the next 10 to 20 years.

Studies done in the seas between New Zealand and Australia found that fished seamounts are 95 percent bare rock, compared to 10 percent on unfished seamounts, which also have double the biomass. Fishing was most intense on seamounts within 650 to 1,000 m of the ocean’s surface

"It’s akin to using bulldozers in a virgin forest to catch a few canaries," Myers says.

Fewer than 150 of the world’s seamounts have been studied in detail because of the difficulty and expense of exploring structures that deep.

But in the past two years, researchers have discovered an astonishing biodiversity, with upwards of 40 percent of species endemic or unique to each particular seamount and new to science, says Frederick Grassel, chair of the Census of Marine Life, a 10-year initiative to pool the world’s knowledge about oceans.

"In some cases, a seamount right next to another may share only 20 percent or so of the same species," Grassel said in a release.

Hundreds of new species are waiting to be discovered on seamounts in the central Indian Ocean, predicts Baban Ingole, a scientist with the National Institute of Oceanography in Goa, India. Some of the known seamounts are covered with sediments instead of coral, and are home to unique species that live 150 years but very little is known about them.

"Seamounts in the central Indian Ocean are in need of protection, otherwise we will lose important species," Ingole told IPS while attending the 10th Deep-Sea Biology Symposium at the University of Oregon this week.

Such protection would not affect local fishers because they work in coastal waters, he added, although Ingole observed that even local fishing boats are getting bigger and travelling further to find fish.

The first seamounts to obtain official protection are the Darwin Mounds, 180 kms off the north west coast of Scotland. This month, the European Commission invoked emergency protection that prohibits the use of bottom trawls or towed nets that contact the bottom of the sea in the area, discovered in 1998.

"We hope this will set the stone rolling for other countries," says Christiensen.

The World Conservation Union (IUCN) is pushing hard to set up marine protected areas for seamounts in international waters, she says, and along with many non-governmental organisations (NGOs) and local governments, it recently launched a 30-million-dollar plan to protect deep water and coastal ecosystems on the west coast of Africa.

While no international body has been tasked to protect seamounts, a group of scientists at the Deep-Sea Biology Symposium planned to petition the U.N. General Assembly to establish one.

The need is urgent, says Myers. "We’re devastating the ecology of the deep oceans."