IN JULY 1992, the Canadian Government closed the Grand Banks, waters off of Newfoundland, and most of the Gulf of St. Lawrence to groundfishing. By the time this moratorium came into effect populations of goundfish, like sole, mackerel, and cod -- fish that live in the Ocean's bottom layer -- had already suffered a catastrophic decline. Most observers pointed to overfishing and damage to habitat by commercial dragnets, as the primary culprits. But by the end of the moratorium, in 1994, it had become clear that the collapse was more serious than at first thought, and that the declines in...