Recovery of UK seabed habitats from benthic fishing and aggregate extraction-towards a cumulative impact assessment

Assessing cumulative impacts of multiple pressures on the marine environment can help inform management response. This requires understanding of the spatial and temporal distribution of human pressures and their impacts. Quantifying seabed recovery rates from 2 significant pressures in European waters, benthic fishing and aggregate extraction, is a significant step towards assessing sensitivity and cumulative impacts. Vessel monitoring system data were used to estimate the distribution and intensity of benthic fishing in UK (England and Wales) marine waters (2006 to 2007). Data were separated by towed bottom-fishing gears (scallop dredges, beam and otter trawls) and linked to habitat in a geographic information system. Recovery periods of seabed habitats were estimated by literature review, for gear types and fishing intensity. Recovery rates generally increased with sediment hardness, and habitats required longer periods of recovery from scallop dredging than from otter or beam trawling. Fishing pressure across the habitat-gear combinations was such that 80% of the bottom-fished area was estimated to be able to recover completely before repeat trawling, based on mean annual trawl frequencies. However, in 19% of the UK's bottom-fished seabed, scallop dredging in sand and gravel and otter trawling in muddy sand and reef habitats occurred at frequencies that prevented full habitat recovery. In 2007, benthic fishing and aggregate extraction occurred together in an estimated 40 km(2) (<0.02%) of the UK seabed. Cumulative impacts were estimated as total recovery time under 4 scenarios: greatest, additive, antagonistic and synergistic impacts. Recovery from aggregate extraction required much greater periods than from benthic fishing, and gravel was identified as a more sensitive habitat than sand.