Scientists on Monday urged Arctic rim nations to set fishing regulations for the Arctic Ocean, and order a moratorium on fishing until stocks are assessed, before trawlers soon start dropping nets in the pristine waters.

"A commercial fishery in the central Arctic Ocean is now possible and feasible," said more than 2,000 scientists from 67 countries in an open letter to Canada, Denmark, Norway, Russia and the United States.

But not enough is known about "the presence, abundance, structure, movements, and health of fish stocks and the role they play in the broader ecosystem" of these international waters as large as the Mediterranean Sea.

The international community must "take action now to protect these waters until we have the science and governance in place to ensure sustainable development of fisheries," the scientists wrote in the letter.

The main barrier to fishing in the Arctic waters is quickly disappearing, as the ice cap melts. Since the summer of 2007, 40 percent of the central Arctic Ocean has been open water.

Soon trawlers from major fishing nations could begin to appear in the far north.

The United States adopted a precautionary approach by closing its Arctic waters to commercial fishing in 2009 to allow scientists to assess the evolving environment.

Canada is also drafting its own fisheries policy for the adjoining Beaufort Sea.

But the scientists fear that "in the absence of scientific data and a robust management system" for the entire region, "depletion of fishery resources and damage to other components of the ecosystem are likely to result if fisheries commence."

The letter was released on the first day of the International Polar Year 2012 science conference in Montreal which brings together the five Arctic coastal countries.