Thirty permanent transects established in 1978 and 1979, were surveyed. Individual stations were permanently marked at 25cm vertical intervals. Abundance scales from the report have been adapted from those in the report, to correspond to the MNCR abundance scale. The sites have been studied in 1978 (R650), 1979 (R282), 1980 (R1073), and 1982 (R530). Permanent transects have been set up to ensure precise relocation of the sites. The relative heights of the top stations of the transects in Whaal Firth were estimated by placing an observer at the top of each transect simultaneously. The position of the water line was noted, in relation to the nearest marked station at a predetermined time. It was assumed that tidal differences in the Firth were negligible to fix the top of each transect at an arbitrary reference level. The general survey methods used are based on those adopted by the Oil Pollution Control Unit (OPRU). The abundance scales and exposure rating scales are described in the 1979 report (R282), as are the sites and stations.