Effect Of Larval Density And Algal Concentration On Growth, Survival And Feeding Rates Of The Scallop Nodipecten Subnodosus (Sowerby, 1835)

The scallop Nodipecten subnodosus is the largest pectinid species targeted in Mexico for hatchery seed production. Thus, effects of larval density (LD = 5, 10 and 15 ml(-1)) and food concentration (FC = 15,000; 30,000; 45,000 and 60 cells ml(-1)) were assessed on survival (S) and growth. Clearance (CR) and ingestion rates (IR) were also studied. Lowest S was observed at 15,000 cells ml(-1) (19%-22%), while S > 50% prevailed at >= 30,000 cells ml(-1). Both LD and FC significantly affected gross growth rate (GGR), with maximal values (7.3 mu m d(-1)) observed at 5 larvae ml(-1). Mean GGR of 6.1 to 6.9 mu m d(-1) was recorded at 10-15 larvae ml(-1) and 45,000 to 60,000 cells ml(-1). Maximal CR (13.8-23 ml larva(-1) h(-1)) was recorded at 15 cells ml(-1). Ingestion rates increased as FC increased, reaching asymptotic values (9.7-11.5 cells larva(-1) min(-1)) at 45,000 and 60,000 cells ml(-1). Allometric IR-Shell height exponents increased (b = 1.1 to 1.9) as FC increased. The combined results suggest that N. subnodosus larvae may be reared at stocking densities from 5 to 15 larva ml(-1) and reach maximal GGR if fed 45,000 to 60,000 cells ml(-1).