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| An alternative
strategy to employ fields of concrete posts water jet-driven into bottom
sand may confront a different set of potential problems (Leighton and
Phleger, 1982). In this scheme, diving would be required to plant and
harvest scallops. Frame structures could be designed which, stocked with
scallops, would rest on the bottom and be raised only for harvest and/or
replanting. It goes without further comment that the variety of cultivation
strategies for the rock scallop are limited only by the imagination.
Juvenile rock scallops need not be cultured in a hatchery. Spat collectors used to accumulate wild set scallops of other species (Leighton, 1991) are also applicable to collection of juvenile rock scallops. Most commonly, fine mesh bags filled with nylon monofilament gill netting are placed in the natural environment for several months (Phleger, Leighton and Cary, 1982) Careful dissection of the monofilament yields young stages of rock scallops together with other species native to the area. A year-long study of larval recruitment by rock scallops, bay scallops and kelp scallops was conducted in which rock scallops settled in spat collectors all seasons of the year (Leighton, 2003, in prep.) Spat collector bags of 1 mm2 mesh were approximately 40 x 60 cm. Each was filled with old gill netting (60 m2, filament diameter 0.25 mm). Pairs of bags were immersed at a depth of 5-10 feet in the entrance to Mission Bay, San Diego, for 2-3 months and replaced sequentially through an 18 month period. |
Juveniles retrieved from spat collectors generally ranged from 2 to 6 mm; the largest individuals being those entering the mesh bags as late-stage larvae soon after installation. Routinely, small juveniles recovered from spat collectors were placed in intermediate culture until reaching a size of about 2 cm. Thereafter, these scallops were grown to maturity in stacked oyster trays suspended by long-line in Agua Hedionda Lagoon, North San Diego County. Acknowledgments
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