Orientation and Distribution of Individual Placopecten magellanicus (Gmelin) in Two Natural Populations with Differing Production

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: MacDonald, B. A., Bajdik, C. D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1992
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Sunnyside; Newfoundland
• Online Access: http://dx.doi.org/10.1139/f92-232; http://www.nrcresearchpress.com/doi/pdf/10.1139/f92-232

Spatial distribution patterns and orientation of individual scallops were determined for two natural populations of the sea scallop Placopecten magellanicus (Gmelin) from shallow coastal habitats in Newfoundland. The orientation of each scallop's dorsal–ventral axis and the positions of individuals relative to each other were determined from a composite image, constructed from a series of underwater photographs, of a grid (256 m 2 ) laid on the bottom at each site. Estimates of the variance to mean ratio for the number of individuals per unit area indicated that scallops from Sunnyside were aggregated, while there was evidence of a haphazard pattern at Colinet. Most scallops from Sunnyside oriented themselves with the exhalant margin facing downstream or at least some portion of the inhalant margin directed into the prevailing current whereas scallops from Colinet were randomly oriented. Differences in density, individual orientation, and patterns of spatial distribution may be partially responsible for differences in growth rates and gonad production observed between the two populations.