Production dynamics of the giant lions-paw scallop Nodipecten subnodosus cultivated off-bottom

Abstract

The dynamics of production of the giant lions-paw scallop Nodipecten subnodosus were studied at a coastal location within the ‘El Vizcaíno’ Biosphere Reserve, Mexico. Production parameters were estimated testing three culture densities. The basis to control cultivation density was 40, 60, and 80% of the area occupied by scallops in nestier-type plastic trays. After 689 days, length was 11.9±0.7, 10.9±0.5, and 9.8±0.5 cm; total weight was 407±13, 310±19.7, and 232±8.5 g; adductor muscle was 44±0.4, 38±2.8, and 26±0.6 g; and survival was 72.7±2.9, 63.5±1.1 and 67.9±1.6% for increasing cultivation density, respectively. Nonlinear regression modeling was used to study the dynamics of production. Invariance tests carried out on parameter estimates of a growth curve indicated a significant negative effect of culture density on growth during the trial (P<0.001). The invariance test on parameters of a mortality curve also produced a significant result (P<0.001), although there was not a systematic negative effect of density on survival. Periodic variations in growth rate were associated with spawning and water temperature. The quadratic equation indicated that a significant relationship existed between gain of muscle weight per day and water temperature (P<0.001). The maximum weight gains occurred in periods when temperature was around 18 °C. An increase in mortality was attributed to the possible synergistic effect of spawning and high water temperature. Maximum muscle yields per tray occurred at the end of the growth trial and were 394, 597, and 674 g for increasing density. The results indicate a complex process of production dynamics that is influenced by density, the reproductive condition of the scallops, and water temperature.