Footage captured on board the boat Tellina by Geoffrey Fox, a research scientist working with the Department of Oceanography, whose job it was to survey the waters of the Blackwater Estuary, in light of concerns about pollution of the oyster fisheries. Oysters have been harvested from the estuary for more than a thousand years. Mr Fox’s job was to collect data to determine if there was a problem with effluent discharged into the waters from the nearby Bradwell Power Station.