Member States shall ensure that all farms rearing bivalve molluscs are registered by the official service, and keep a record of live bivalve molluscs entering and leaving the farm. Member States shall ensure that a monitoring and sampling programme is applied in bivalve mollusc farms in order to observe whether there is an abnormal mortality and keep track of the health situation of stocks. Sampling and laboratory testing for the determination of the cause of abnormal mortality of bivalve mollus