Marine Scotland uses FRV Scotia to undertake a deep-water trawl survey along the continental slope of the Rockall Trough. The broad aim of the survey is to collect fisheries-independent data on the fish populations of the deepwater slope west of the Hebrides. As with any new survey, there is often a period over which the survey develops both from a technical and a scientific perspective. The deep-water survey developed over a longer period than most owing to the fact that it was initially only run once every two years and because it is a technically challenging survey due to the great depths to which it samples.

The purpose of this manual is to describe how the survey developed and, now the development phase is over, to document as precisely as possible the current (2010) protocols and methods that are considered standard.