Production, dynamics and energy partitioning in two populations of the giant scallop Placopecten magellanicus (Gmelin)

Abstract

The quantities of energy invested in gamete production, somatic tissue growth and synthesis of the organic matrix in the shell were determined for two non-exploited populations of Placopecten magellanicus (Gmelin) in Newfoundland. Individuals from one population (Colinet) exhibited slow growth rates, a low reproductive output and low P B ratios compared with scallops from the other population (Sunnyside). The population density at Colinet was, however, greater than at Sunnyside, resulting in a higher population production at the former location. At Colinet, young age classes were well represented, and these animals contributed considerably to population production, of which 46% was exported as gametes. At Sunnyside, older age classes dominated the population, resulting in a shift in emphasis from growth to reproduction, the latter accounting for 72% of population production. Comparisons were made between P. magellanicus and two other pectinids for which population data are available, Chlamys islandica (O.F. Müller) and C. varia (L.).