The Scottish Quarter 3 Rockall survey began in 1985 and was carried out annually until 1997. However, in 1998 it was decided to make the survey a bi-annual event; in 1998 a new survey of deep water stocks was completed, in the future the Rockall survey and a deep water survey will occur in alternate years. The Rockall surveys will generally be in September during odd numbered years. The survey covers only a relatively small area, in the order of eight ICES rectangles. Trawl stations are on known clear tows and vary between 2 and 8 per rectangle depending on the proportion of the area within the 250m depth contour.