Why did the East Coast Fishery collapse?

According to Canada History, the East Coast Fishery collapsed due to the inability of the government to regulate the volume of cod being fished from the Grand Banks. By 1995, the fishery had completely collapsed, with an estimated cod bio-mass left at a mere 1,700 tons.

In 1976, in an attempt to let the cod population have a chance to recover, Canada and the United States extended their marine jurisdiction, keeping foreign vessels out of the water. This decreased the amount of cod caught in 1978 to 139,000 tons, a manageable rate. However, modernized fishing equipment and domestic ships replacing foreign ones pulled the number back up to 250,000 tons by 1984.