Growth of scallop juveniles (Pecten maximus L.) in an enriched shallow seawater basin

The aim of this work was to see if a shallow, enriched seawater basin was a suitable location for scallop culture. Growth of great scallop juveniles (Pecten maximus L.) was compared with two open sea locations, and the mean growth rate is described for 23.1-29.5 mm juveniles in three intervals from early April to late September 1989. In 1990 the mean of individual growth rate is described for 30-65 mm juveniles in April, May, June and July. Growth was measured as increase in shell height. Temperature, salinity and particulate organic material, POM, (1990) were recorded twice every week Phytoplankton (1989) was observed weekly. Mean growth rate per individual (mm/30 days) in 1989 was, relative to the other locations, higher in the basin in April-May, approximately equal in May-July and lower in July-September. The relative high growth rate in April-May coincided with relative higher temperature and phytoplankton biomass. The low growth rate in the basin was observed in a period of equal temperature relative to the other locations, higher phytoplankton biomass, but with large variations in salinity (25-31 ppt). In 1990 there were no significant difference in mean of individual growth rate between the locations, except for in June. The low growth rate and high mortality observed in the basin this month coincided with very high POM values (mean=17 mg/l, maximum =31 mg/l). The conclusion so far is that the seawater basin is suitable for culturing scallop juveniles, given a certain manipulation with salinity, fertilization and water circulation.