Sea traffic in the famed Northwest Passage will soon be monitored by underwater listening devices to be installed by Canada to bolster its disputed claim over the Arctic. Canada's military will start keeping tabs on trespassers -- ships and submarines -- in the region as early as mid-2008, said public broadcaster CBC. The detection technology is to be installed at Gascoyne Inlet on Devon Island, near one of the main arteries of the passage that links the Atlantic and Pacific oceans, the CBC said, citing unnamed sources. Canada is at odds with Russia, Denmark, Norway and the United States over 460,000 square miles of Arctic seabed. Each nation is claiming overlapping sections of the sea floor, believed to hold 25 percent of the world's undiscovered oil and gas reserves.