Annual Celtic Sea herring acoustic survey into the abundance and distribution of target fish species undertaken by the Marine Institute. FSS (Fisheries Science Services) within the Marine Institute carry out annual acoustic surveys in the Celtic Sea (ICES Division VIIj, g and VIIaS) to assess the size of the stock in these waters. The acoustic survey programme was first implemented in 1989 and has continued annually since. The information collected is used to provide a measure of the relative abundance of herring in the survey area.