In 1972, Iceland unilaterally extended its territorial waters before announcing plans to reduce over-fishing. It policed its quota-system with warships, leading to a series of encounters with the British trawlers that fished the areas. As a result British Royal Naval vessels were employed to act as a deterrent against any future harassment of British fishing crews.
In 1976, a compromise between the two countries allowed a maximum of 24 British trawlers access to the disputed 200 mile / 320 km limit. This did nothing to help slow the decline of the British fisheries, severely affecting the economies of northern fishing ports such as Grimsby and Kingston-Upon-Hull.