Respiration and energetics in mussels ( Mytilus edulis L.) cultured in the White Sea

Energy budget was calculated for the cultured mussel population on net substrata of the mussel farm (10 000 m 2) in Chupa Inlet, the White Sea. Seasonal changes of respiration rate of the White Sea mussels depended on both sea-water temperature and stage of gonad cycle. Maximal values of respiration rate were recorded in late spring and June, minimal ones in winter and early spring. Caloric content of the whole mollusc (with shell and mantle fluid) was 210 cal/g. Maximal values of energy flow in the cultured mussel population were observed in summer; however, net production efficiency in autumn was higher than in summer. This coefficient for the investigated mussel population was equal to 0.19 in 4 years. Total biomass eliminated during the observation period was 60–80% of the total production in different size groups. For 1 kg increment in biomass (i.e. 210 kcal), the White Sea mussels needed about 2300 kcal of food. During the 4-year cultivation period the investigated farm (10 000 m 2) withdrew about 710 * 10 6 kcal from the environment. Of this, 30% was returned into the ecosystem with faeces and 8% due to elimination, 56% was dispersed due to metabolism and only 6% (about 220 t) remained as terminal biomass on the net bands which may be harvested.