MEPS 128:225-238 (1995)  -  doi:10.3354/meps128225

Effects of site and season on movement frequencies and displacement patterns of juvenile sea scallops Placopectenmagellanicus under natural hydrodynamic conditions in Nova Scotia, Canada

Carsen AE, Hatcher BG, Scheibling RE, Hennigar AW, Taylor LH

In this study, we examine the effect of site and season (spring vs fall) on the movement frequency and net displacement of juvenile sea scallops Placopectenmagellanicus, and the relationship between the net movement direction of scallops and the near-bed current direction at 2 sites in Lunenburg Bay, Nova Scotia, Canada. At each site, a total of 150 and 100 individually marked juvenile sea scallops were released on the sea bed at 2 points (Stns 1 and 2) placed 50 m apart for the spring (March) and fall (September) studies. The movement frequency and net displacement of the scallops were monitored within a 10 m radius from the release point approximately once a week during the spring study, and once a day during the fall study. Current meters placed 60 cm off the sea bed recorded near-bed current velocity. There was a significant interaction between site and season on the movement frequency of scallops. Scallop activity was low during the spring study at both sites when ~30% of scallops were found at their release point on the sea bed after 30 d. Scallops were much more mobile during the fall study when <5% of scallops were found at their release point after 2 d. However, the net daily displacement was <3 m for more than 60% of scallops recorded. In ~50% of the surveys, the net movement direction of scallops was significantly related to the direction of the main current vectors over daily to monthly periods, whereas in the other cases the net movement direction was independent of the direction of the main current vectors. The results of this study indicate that local hydrodynamics is not a good predictor of the swimming dispersion of juvenile P. magellanicus in natural habitats.


Currents . Displacement patterns . Juveniles . Movement frequencies . Placopectenmagellanicus . Sea scallops


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