Rearing panel several months after removal of mesh covers. Young scallops at this point have grown beyond the limits of the wells. Panels are 16 x 24 inches.

The single case of paralytic shellfish poisoning reported for ingestion of rock scallops involved this tissue (Leighton and Phleger, 1981).

Discussion of Strategies for Aquaculture of Rock Scallops

     Studies of rock scallop growth rates in southern California show a shell diameter of 10-12 cm may be reached in two years of grow-out from a juvenile size of 1 cm (Leighton and Phleger, 1981). Young scallops held at a series of depths in the ocean off La Jolla from15 feet to 400 feet grew most rapidly at 30 feet, slightly less at 100 feet, and considerably less at depths of 200, 300 and 400 feet (Leighton, 1979).

     These results suggest the potential for maximal growth of rock scallops exists at depths of 30 to at least 100 feet in the phytoplankton-rich oceanic water overlying vast areas of shelfland off the southern California coast. Buoyed long lines to suspend rearing cages in mid-water column or bottom-situated strategies could be applied to large-scale rock scallop cultivation programs.

     Even a modest program to cultivate shellfish in protected waters of bays and estuaries in southern California is bound to become limited by fishing, boating and other activities. Occasional episodes of pollution, storm runoff salinity reduction, excessive eutrophication (algae blooms) and maintenance problems with fouling are elements which may adversely influence production of rock scallop crops.

     Open ocean aquaculture, especially in southern California, would appear highly promising and free of many of the problems foreseen for the bay-based operation. The relatively vast three-dimensional space overlying bottom in the depth range 50-300 feet in the Southern California Bight could support major-scale rock scallop grow-out operations.

     Considerations applicable to mid-water column long line-suspended stacked tray or panel array rock scallop grow-out systems include ease or difficulty of tending and harvest, selection of appropriate depth for primary anchors and level of submerged long lines, and problems with drift kelp entanglement, possible creation of navigation hazards, and competitive use of a portion of the sea in the public domain.