this might be a useful link to UN Oceans and Law of the Sea:
http://www.un.org/Depts/los/index.htm
http://www.un.org/Depts/los/LEGISLAT...N_1996_Act.pdf
some where in all the legalese, there may be a relavent tidbit
Continental shelf
17. (1) The continental shelf of Canada is the seabed and subsoil of the submarine areas, including those of the exclusive economic zone of Canada, that extend beyond the territorial sea of Canada throughout the natural prolongation of the land territory of Canada:
(a) subject to subparagraphs (b) and (c), to the outer edge of the continental margin, determined in the manner under international law that results in the maximum extent of the continental shelf of Canada, the outer edge of the continental margin being the submerged prolongation of the land mass of Canada consisting of the seabed and subsoil of the shelf, the slope and the rise, but not including the deep ocean floor with its oceanic ridges or its subsoil;
(b) to a distance of 200 nautical miles from the baselines of the territorial sea of Canada where the outer edge of the continental margin does not extend up to that distance;