Plasticity of attachment in the purple-hinge rock scallop, Crassadoma gigantea: Implications for commercial culture

Abstract

Advancement of commercial culture of the purple-hinge rock scallop, Crassadoma gigantea, requires the development of efficient and cost-effective grow-out techniques. Use of traditional bivalve culture methods (e.g., lantern nets, oyster trays, pearl nets) is not feasible because rock scallops typically attach by cementing the right shell valve to the gear. Subsequent harvesting often results in damage to the animal and/or gear. We examined plasticity of attachment of rock scallops, and the effects of attachment on growth, to determine whether attachment could, and should, be facilitated when culturing this species. Laboratory and field experiments suggested that developmental and environmental factors influenced attachment, explaining some of the variation in size of attachment within and among locations. Rock scallops did not attach until reaching a minimum size (∼ 25–30 mm shell height) in south-central California. Attachment was facilitated by flat, hard substrates, but inhibited by fibrous substrates. For scallops larger than the minimum size (> 30 mm shell height), attachment was not affected by prior attachment history (attached and dislodged) or scallop size. Growth rate (shell deposition and tissue growth) was higher for attached scallops. Our results suggest that attachment can, and should, be facilitated when culturing C. gigantea.