Changes in fish and benthos catches off the Danish coast in September 1981

During a routine North Sea demersal fish survey, very low fish catches were recorded at two primary stations off the Danish coast in September 1981. The catch of benthos at thesestations was much greater than the previous year, and underwater photographs from a headline camera revealed that this was a result of most infaunal species having emerged from beneath the sand. The phenomenon was assumed to be caused by low oxygen concentrations in bottom water following the collapse of a bloom of the dinoflagellate Ceratium furca .