Defra and partner agencies have completed a thorough investigation of the cause of dead crabs and lobsters which were found washed up on the North East coast between October and December 2021. Following significant testing and modelling to rule out possible causes, Defra and partner agencies consider that the deaths of the crabs and lobsters potentially resulted from a naturally occurring harmful algal bloom. From the evidence found during the investigation it is unlikely that chemical pollution, sewage or infectious aquatic animal diseases were the cause of the deaths. No traces of chemical c…