ICES Statistical Rectangles and Areas
International Council for the Exploration of the Seas (ICES) standardise the division of sea areas for statistical analysis. Each ICES statistical rectangle is '30 min latitude by 1 degree longitude' in size which is approximately 30 nautical miles by 30 nautical miles*. A number of rectangles are amalgamated to create ICES areas.
*Because the Earth is a spheroid shape, the area of an ICES rectangle will vary by latitude. In Scottish waters, the average area of a rectangle is 940 nautical miles square, but varies between 801 and 1056 nautical miles square.