Age and growth rate determinations for the Atlantic ribbed mussel, Geukensia demissa Dillwyn (Bivalvia: Mytilidae)

Field studies were conducted in Westport, Connecticut, to determine linear shell growth rates for Geukensia demissa. These rates were then compared with those reported for the same species from other locations. Most shell deposition occurred from March through November of each year. Winter interruptions in growth were clearly recognized in all size mussels and the rings were a reliable method for determining age in mussels from Westport. No significant sexual dimorphism in mean annual growth rates was detected. Age-size relationships based on internal shell lines appear to be less reliable, probably because of the interference by shell erosion at the umbo in this species. No well-defined latitudinal patterns in growth could be established for Geukensia demissa.