Seasonal changes in condition and biochemical composition of the scallop Pecten maximus L. from suspended culture in the Ria de Arousa (Galicia, N.W. Spain) in relation to environmental conditions

Abstract

Seasonal changes in condition and biochemical composition of striated adductor muscle, digestive gland and female gonad of raft cultured Pecten maximus L. in the Ria de Arousa (Galicia, N.W. Spain) were studied over 16 months in relation to environmental conditions and reproductive events. Pecten maximus in the Ria de Arousa showed a clear cycle of energy storage and utilisation. Between March–April and October carbohydrates and proteins were accumulated in the striated adductor muscle and lipid in the digestive gland. From October to March of the following year there was a loss of such energy reserves. In the ovary there were two annual periods (winter and spring) of increase in the energy content owing to the gonad recovery, which were characterised mainly by the rise in the percentage of lipid. This correlated positively with the gonad condition index and with the mean diameter of the oocytes. The energy necessary for the gametogenesis in late autumn and winter (from October to March) was supplied by the reserves of the striated adductor muscle and the digestive gland; the energy provided by the adductor muscle was double that supplied by the digestive gland. Part of this energy was also used to support the basic metabolic maintenance requirements. The contribution to the energy loss (from October 1990 to March 1991) of the striated adductor muscle carbohydrate and protein and digestive gland lipid was similar (32.45, 27.06 and 29.15 kJ respectively). In spring the gametogenesis took place at the expense of the available food which was also sufficient to allow concurrent energy storage in the adductor muscle and the digestive gland.