Argopecten purpuratus hatchery technology is primarily based on batch systems with 100% of water exchange per day and rearing volumes ranging from 500 L to 70 m3. Recently, a RAS technology was investigated and yielded satisfactory results for the production of postlarvae and early juvenile scallops. I n this study, we assessed RAS productive performance at various rearing densities (20, 40, 80, and 120 larvae/mL), with a batch system at a common rearing density of 15 larvae/mL serving as a control. Later, the young juveniles were reared in suspended systems for 60 days at Tongoy Bay to evaluate their juveniles’ yield.
Two spawnings were performed sequentially every 20 days. Sixty scallop broodstocks with an average of 7.5 cm of shell length were taken from a population of 200 specimens from a suspended system located in Tongoy Bay for each spawning. The RAS had twelve 250 L flat- bottom cylindrical tanks, a water pump (Vulcano 0.3 hp), a UV sterilizer (Ql-40 Bioligth), 2 biofilters, and air injection from a turbo blower (Sweetwater) .
RAS provided stable water quality conditions for rearing scallop larvae at densities of 40, 80, and 120 larvae/mL . Competent larva e (220 µm shell length) were obtained after 11 days of culture in all RAS, but it took at least 21 days in the batch control system . L arval morphology at high rearing densities appears uniform without shell damages as compared with those reared in a batch system, which can potentially increase the mortality of the larvae and juveniles. The production of 5-13 mm juveniles after 60 rearing days in longlines was better for RAS in comparison to the typical batch technology. Results reported in this research would significantly improve rearing protocols and the design of recirculating aquacultural systems for hatchery production of juvenile scallops.