Evaluation of alternative suspended culture methods for the commercial scallop, Pecten fumatus Reeve

Commercial scallops, Pecten fumatus, glued to plastic mesh disks showed growth and survival equal to or greater than similar sized scallops in conventional earhung and cage culture. In two experiments of 13 and 25 weeks duration, some aspects of disk culture, such as spacing between disks, scallop orientation and the choice of valve by which the scallops were glued, were examined to determine their effects on shell growth, somatic tissue weight increase, predation and survival. As disk spacing was increased through 40, 60, 80 to 100 mm, predation increased at disk spacing greater than 60 mm and total soft tissue mass peaked at 60 mm and above. There were no significant differences in soft body weight or shell height between scallops glued by either valve in either normal (flat left valve uppermost) or inverted (cupped right valve uppermost) orientation. However, scallops glued by the left valve had higher percentage survival and larger muscle weights regardless of orientation. By contrast, those glued by the right valve had heavier gonads. Orientation and the scallop culture technique employed significantly affected spionid polychaete infestation of the shell. Scallops glued by the left valve, with left or right valve uppermost, and glued by the right valve with this valve uppermost had significantly lower polychaete prevalence than scallops contained in cages, earhung or glued by the right valve with left valve uppermost.