Experts at the United Nations have compiled a report calling for a moratorium on seabed trawling on the high seas to protect vulnerable deep-sea ecosystems, Japanese experts said Wednesday.

The report will be submitted this fall to a U.N. General Assembly session on environmental conservation on the high seas, they said.

Conservation groups and marine biologists are against seabed trawling, but the Japanese government and fisheries industry oppose the view that it is harmful to deep-sea habitats, claiming the argument is not sufficiently grounded in scientific fact.

Compiled in response to U.N. resolutions in 2004 and 2005, the report cites deep-sea bottom trawling as one of the “destructive fishing practices” that has raised particular concern because of its adverse impact on marine ecosystems.

Nations and regional resource management organizations have taken steps to address the impacts close to home. However, this is not the case on the high seas, where the report says deep-sea habitats are extremely vulnerable and require protection. The paper says there is an urgent need for preventive action.

Large-scale trawling may be more damaging to deep-sea species because they tend to grow slowly, the experts said, adding there already are signs of overfishing in some some areas.

Some evidence suggests that bottom trawling and dredging have the “most obvious disruptive impact due to their widespread use and their contact with the bottom,” removing organisms, rocks and sediments and reducing habitat complexity, the report says.

“In addition, by-catch of nontarget species can be high. It is believed that about 95 percent of the damage inflicted on deep-water systems associated with seamounts results from bottom trawling.”

According to fisheries officials, Japan was once the biggest practitioner of bottom trawling, but the number of vessels has shrunk and their catches have been outpaced by those of European nations. Bottom trawling is also extensively practiced by Russia, China and South Korea, they said.

An official of Japan Deep Sea Trawlers Association said the argument that bottom trawling inflicts irrecoverable damage on marine ecosystems is “exaggerated.”

With recent technological innovations that show the topography of the seafloor and the movements of trawl nets, trawls hardly sweep over the seabed haphazardly any more, he claimed.

At the same time, bottom trawling has increased substantially, starting in the 1980s with the introduction of better technology. Commercial fishing has expanded into deeper waters, with vessels now dropping nets to depths of more than 400 meters — and sometimes to between 1,500 and 2,000 meters.

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