We have recently explored use of an incubator with controlled photoperiod and temperature for larval culture (Fisher Scientific, Diurnal Growth Chamber). Larvae are contained in capped 1-liter plastic bottles, laid horizontally on motor-driven rollers (see figure below). Controls are set to provide 18-20^oC, a photoperiod of 14 hr light/10 hr dark, and a bottle rotation rate of one turn per minute. Cultures are meshed out once each 3-4 days and new food supplied. Larvae placed in the incubator system at an age of one week reach 200-220 µm within another three weeks. Eyed larvae competent to metamorphose are then transferred to the systems described above.

     Once juvenile scallops reach 2-3 mm (about three months postfertilization), their nutrition is better satisfied by feeding on natural phytoplankton. Bags constructed of fiberglass window screen serve well to confine early juveniles held in the bay or sea.
As size increases, larger mesh cages are used. We find quarter inch (6 mm) polyethylene mesh is most suitable for containment of young scallops of 1 cm shell height.

     Juvenile rock scallops begin to cement to surfaces when 2-3 cm in shell height (age ~ six months). Cementation occurs at a larger size in rock scallops in northern regions.

Final Grow-out

     Rock scallops may be reared from 1 cm to market size (10-12 cm) in a two year period. Oyster trays are now available in a variety of configurations, all of which are suitable for containment and grow-out. A difficulty exists when scallops cement either to each other or to the cage itself. This problem is dealt with by removing scallops to newly cleaned trays each few months. This measure is also important to avoid excessive overgrowth by fouling organisms.

     Rock scallops will incorporate meshing of lantern nets, pocket nets and related cages into their shells, making harvest difficult and often leading to damage of the containment device.

     Another approach to grow-out of rock scallops mentioned earlier was developed by the author.