DISPERSION AND MORTALITY OF A POPULATION OF SEA SCALLOP (PLACOPECTEN-MAGELLANICUS) SEEDED IN A TIDAL CHANNEL

Ten thousand scallops (Placopecten magellanicus) from 4 to 26 mm shell height were released in 40 m(2) of an 8 m deep tidal channel in Lunen burg Bay, Nova Scotia, Canada. Their survival, distribution, and poten tial predators were monitored during the 13 months following release i n November 1990 using quadrat and video surveys. Both dispersion and m ortality were rapid during the first 2 weeks, when predation by crabs and starfish was estimated to have killed about one half of the seeded population. The rate of loss decreased markedly over the following wi nter and spring. Dispersion of seeded animals increased again through summer and autumn, producing a final scallop density of about 2 m(-2) (twice that of the natural population), covering more than 3500 m(2) o f seabed. This expansion was accompanied by little further mortality, and the final estimate of survivors in the expanded survey area was 40 %. Scallop displacement was directional, but the mean vector did not m atch that of the dominant, near-bed water currents. The average growth (shell height increment) of surviving scallops was 35 mm in 13 months . Our results demonstrate the potential for ecologically viable bottom culture of the species in coastal Nova Scotia.