Dynamics of juvenile sea scallop (Placopecten magellanicus) and their predators in bottom seeding trials in Lunenburg Bay, Nova Scotia

Thousands of juvenile sea scallop (Placopecten magellanicus) were released on the sea bed in summer and winter at two sites (a topographically open and an enclosed site) along the southwestern coast of Nova Scotia, Canada. Seeded and wild scallops and their predators (sea stars Asterias vidgaris and A. forbesi and rock crab Cancer irroratus) were monitored by video and diver surveys over 17 mo. Following release, the density of seeded scallops rapidly decreased, and stabilized after 1-8 wk; variation in final densities was greater between sites than between seasons of seeding. Seasonal temperature affected the rate at which the final densities were attained. Seeding effectively doubled scallop density at each site. Survivorship was ∼10% due to loss from crab predation and dispersion of seeded scallops at the open site and ∼1% due to mainly crab predation at the enclosed site. Temporal variation in abundance and spatial distribution of predators was not correlated with that of seeded scallops, suggesting that predatory mortality of seeded scallops was due to a functional response, rather than an aggregative response of predators. Growth of seeded scallops was similar at both sites. The dynamics of the seeded scallop populations reflected the interaction of predation, dispersion, and growth.