This dataset includes “theoretical closures of Great Scallop fishing areas”  due to Harmful Algal Blooms (HABs) from 2011 to 2020. For each fishing area, the number and duration of closures have been estimated through an algorithm applied to the dataset from the French monitoring network REPHYTOX and information related to the monitoring and the management of the Great Scallop fishery in the Eastern English Channel. This dataset has been produced within the framework of the FCE Interreg S3-EUROHAB project which deals with the detection of HABs events based on satellite products and the assessment of their impacts in the French-English Channel. These data only cover closures related to sanitary threshold exceedances of phycotoxins in shellfish. This dataset can be used to assess the impacts of harmful algal blooms on scallop fisheries, but the algorithm can be applied to other species, other areas, and other economic activities. Management areas of scallop which correspond to the sampling areas, as shown in the variable "Lieu de surveillance : Libellé" in REPHYTOX data, are associated to this dataset in a shape file format.