Spatial variability in distribution and growth of juvenile and adult sea scallops, Placopecten magellanicus (G.), on eastern Georges Bank (Northwest Atlantic)

International audienceSpatial distribution of juvenile and adult sea scallops Placopecten magellanicus (Gmelin) was studied from video-monitored sled-dredge samples in commercial scallop beds of eastern Georges Bank (Northwest Atlantic). Maximum densities of 1 and 2 yr old individuals, as well as of adults, were recorded in the northern area of the study. Abundance of scallops was significantly higher on gravel than on the other sediment types. Scallops appeared to exhibit a Poisson distribution within sediment type. Distribution of juveniles only partly matched that of adults; age 1 individuals were less dispersed than 2 yr olds and adults, and were mainly located on a gravel-pebble deposit in the northern half of the Bank. It is inferred that movements associated with tidal currents occur as the individuals grow older. The relative abundances of pre-recruits and recruits emphasize the impact of fishing activity on size structure. Growth parameters of the von Bertalanffy function would indicate that Lee's phenomenon acts on the population. Age 2 juveniles showed a strong depth-related decrease in shell growth, linked to temperature and probably to food availability. The sampling technique employed has the potential for establishing pre-recruitment indices for use in management of this fishery