Spatial distribution of total international otter and beam trawling fishing effort, for all ICES rectangles (0.5 degree latitude by 1 degree longitude) of the North Sea, covering a 31-year time span from 1985 to 2015. The dataset was largely reconstructed using compiled effort data from 7 fishing effort time-series and completed by estimations of missing data. Lat and Long coordinates in the data represent the centre of each ICES rectangle. For the 31-year period from 1985 to 2015, we collated or estimated data on total (demersal) otter and beam trawling effort per year for the North Sea, defined as ICES Sub-area IV. Specifically, the effort was quantified as number of hours fishing in a year per ICES rectangle. For each year we compiled data on trawling effort by vessels landing in Belgium, Denmark, England, France, Germany, the Netherlands, Norway, Scotland and Sweden, which are the most significant contributors to trawling effort in the region. Where data for a particular country and year was missing it was estimated, based on the spatial distribution of trawling effort by that same country in other periods, and on the average percentage contribution of the trawling effort by that country to the total. For each year and ICES rectangle the dataset specifies "Compiled" and "Estimated" effort, and additionally provides a "Reconstructed" effort which is the sum of the two. Sources for compiled effort data include the STECF (Scientific, Technical and Economic Committee for Fisheries), the MAFCONS Project (Managing Fisheries to Conserve Groundfish and Benthic Invertebrate Species Diversity), datasets from scientific publications, and national databases for England, Scotland and Denmark.