Previous data suggest that Greenland halibut comprise a single self-sustaining stock from Davis Strait to the Grand Bank and Flemish Cap.  Fish in the Gulf of St. Lawrence are believed to be a separate, relatively small self-sustaining stock, which receives migrants from the Labrador area through the Strait of Belle Isle between Quebec and the island of Newfoundland.  The major spawning location in the western Atlantic is in the deep slope area of Davis Strait along the boundary between Canada and Greenland. Canadian managers are particularly concerned about the relationship of Greenland halibut outside the 200-mile economic limit on the Grand Banks of Newfoundland and adjacent waters to those within the Canadian economic zone as far north as Davis Strait.  For example, do fish outside the 200-mile limit on the Grand Banks and adjacent waters constitute a separate stock, or do they instead comprise an extension of the distribution from Davis Strait southward along the deep edge of the continental slope?  Fish in spawning condition have been reported from the deep slope area off the coasts of Labrador and northeast Newfoundland to as far south as Flemish Pass: are they migrants from the Canadian Zone? The implications for fisheries management can be quite complex considering the possible scenarios for stock structure.  [adapted from Vis et al. 1997]