In recent years conflict has arisen between conservation groups and commercial fishing interests over perceived trawl damage to the benthic communities in Strangford Lough. Data from a number of survey techniques were combined to assess the impact of trawling on the benthos of the lough, principally on the diverse communities associated with the horse mussel, MODIOLUS MODIOLUS beds. The target species of the otter trawl fishery is the queen scallop, AEQUIPECTEN OPERCULARIS.Fisheries data were recorded and a quantitative species bycatch list was compiled. The fishery is confined to a small number of local-based vessels and existing regulations seem adequate. Otter trawls with rollers (separated by discs) on the footrope were found to collect less bycatch, including notably fewer M. MODIOLUS, than trawls with a plain, continuous footrope.The major bottom types and associated benthic communities present in the lough were mapped out using an acoustic bottom classification system, RoxAnn, in conjunction with underwater cameras. Visual data were statistically analysed to quantify the effects of trawling and certain benthic species were found to be significantly associated with M. MODIOLUS. Trawling was found to remove emergent epifauna and to reduce the structural complexity of the mussel bed, giving an overall flattened appearance. Grab sampling was used to further investigate the effects of trawling on benthic community structure, particularly the infaunal component of the benthos.Side-scan sonar was employed to locate areas of the lough bed physically impacted by trawling. Otter boards were found to imprint distinct trawl marks on the lough bed and were identified on side-scan records. During the surveys a Geographical Information System (GIS) was successfully employed as a data management tool.Based on this study, possible strategies for future management of the queen scallop fishery and Strangford Lough as a marine nature reserve have been discussed.