The broad-scale effects of salmon farming on benthic and epibenthic macrofaunalcommunities of four Scottish sea lochs (Kishorn, Duich, Hourn and Nevis) with differentaquaculture loadings were investigated based on the first benthic surveys to be undertakenin these lochs. Significant variation in the benthic communities was identified betweenlochs, mainly related to differences in the abundance of echinoderms and polychaetes (thedominant components of the benthic communities). Variance partitioning using partialredundancy analysis suggested that approximately 9.6% of this variation could be relatedto aquaculture activity in the lochs (as expressed through “production” and previouslymodelled “impact” levels), as compared to 20.6% attributable to measured environmentalfactors. Epibenthic communities were dominated by echinoderms and arthropods and there wasno significant between-loch variation in epibenthic community composition. No significantdifferences were apparent in the benthic or epibenthic community assemblages betweensamples taken within 2000 m of a fish farm and those taken beyond this distance. Ingeneral, our results support previous studies suggesting a spatially limited impact ofsalmon culture installations on the benthos, although impacts on the aquatic food web on awide spatial scale cannot be ruled out and the link between benthic community variationand aquaculture variables identified through variance partitioning requires furtherinvestigation.