Hatchery Production of Scallop Larvae (Pecten maximus) – Survival in Different Rearing Systems

Scallop farms in Norway rely exclusively on hatchery production of spat. Larval rearing is one of the most difficult parts of the production, and several experiments have been performed during the last years to improve the larval systems. This paper describes results from commercial and experimental trials obtained between 1996 and 2001. Four different rearing systems were compared: untreated batch cultures, chloramphenicol-treated batch cultures, flow-through cultures with filtered water and flow-through cultures with water from a biofilter. The chloramphenicol-treated batch cultures had overall significantly higher survival rates than the untreated and flow-through cultures. There were no significant differences in survival between untreated and flow-through cultures. The average survival rates for the untreated, treated and flow-through cultures were 6.8, 23.0 and 8.6%, respectively. No significant seasonal differences were found for the untreated and treated larval groups, whereas for larvae reared in flow-through systems survival was significantly higher in the winter than the spring. Overall best results were obtained during winter in years with high salinity water in the fjord.