AbstractMussels (Mytilus edulis L.) were experimentally cultured at 12 sites (1.5 km intervals) in an estuarine gradient on the Damariscotta River, Maine. Growth, survival, and recruitment of mussels were monitored and hydrographic data were collected. Peak growth of mussels occurred in May and June. The 4 upper‐estuarine sites were characterized by (1) earlier timing of peak growth, (2) suppressed growth in June and July relative to lower estuary mussels, and (3) marked mortality in September. Mussels grew rapidly in the lower 10 km of the estuary, exhibiting different temporal patterns of growth, but achieving comparable seasonal growth and survival. Seed mussels used for the growth experiments had settled on collectors during the previous summer and, accordingly, grew to 50 mm length in approximately 12 months: 15 months of growth yielded 57–71 mm mussels. Recruitment varied considerably, but was consistently high throughout the middle estuary, where settlement densities of 5–8 seed mussels per cm2 were observed. A 5‐year record of spatfall at one site in the middle estuary indicated that recruitment there was relatively consistent from year to year. The high mortality of mussels in the upper estuary of the Damariscotta River was associated with temperatures of 20°C and above, but may be related to factors other than temperature stress per s***a. Reduced ration during periods of warm temperature and increased metabolism may be responsible for these mortalities. Dense populations of newly‐settled mussels survived at some locations where temperatures exceeded 20°C and adult mortalities were high, indicating that high settlement densities and the existence of extensive populations of very young mussels do not, by themselves, provide enough information to adequately assess the potential of a site for mussel aquaculture. This potential may be meaningfully assessed by the use of a small experimental mussel raft and the collection of temperature and salinity data. Our results indicate that extensive areas of estuaries similar to the Damariscotta may be utilized for the culture of mussels.