Human activities in UK offshore waters: an assessment of direct, physical pressure on the seabed

Abstract Eastwood, P. D., Mills, C. M., Aldridge, J. N., Houghton, C. A., and Rogers, S. I. 2007. Human activities in UK offshore waters: an assessment of direct, physical pressure on the seabed. – ICES Journal of Marine Science, 64: 453–463. Integrated assessments (IA) and marine spatial planning (MSP) are becoming major drivers for the assessment and management of human activities at sea. To be successful, both require an understanding of the distribution of the pressures caused by human activities. We used spatial data for the major human activities operating in the England and Wales sector of UK waters in 2004 to provide an assessment of direct, physical pressure on the seabed from multiple human activities. Pressure was estimated as the spatial extent of each of the activities; the intensity, longevity, and impacts arising from the pressures were not considered. Estimates of spatial extent were assigned to three pressure categories, subdivided into six pressure types. We estimated that four of the six pressure types affected < 1% of the seabed of England and Wales in 2004, whereas selective extraction caused by demersal trawling affected a minimum of 5.4%, rising to a possible maximum of 21.4%, of the total area of the seabed. This was a greater area than all other pressure types combined. The assessment process described here can be used as the framework for reporting human pressures at regular time intervals and feed into both IA and MSP for regional seas.