Surveys were conducted in two shallow bays in the Orkney Islands, UK; Orphir Bay, an unexploited (control) site, and Bay of Ireland, a fished site, to investigate the effects of suction dredging on the resident razor clam, Ensis arcuatus, populations. A lower density and significantly smaller mean length of razor clams were present at the dredged site compared with the control site. The age of individual razor clams was estimated using internal shell microgrowth patterns, visible in acetate peels of polished and etched shell cross-sections. Ensis arcuatus are relatively slow growing animals with the two study populations characterized by old individuals and an obvious lack of juveniles, indicating populations with little resilience to disturbance. An analysis of the shell sections of razor clams from the Bay of Ireland revealed the presence of shell margin breaks, consisting of deep clefts in which sand grains were embedded in the shell matrix, whilst those from Orphir Bay had fewer disturbances to shell growth. It is suggested the disturbances to shell growth are the result of repeated suction dredging operations in the Bay of Ireland. In situ reburrowing experiments were conducted to determine the survival rate of E. arcuatus (<160 mm shell length), returned to the sea after capture and to estimate the indirect effect of dredging on the razor clam population. These individuals displayed a slow initiation of “escape-digging” which rendered them vulnerable to attack from predatory crabs and fish, indicating that there is likely to be a low survival rate of any returned undersized clams or ones that are disturbed and escape from the suction dredge.