A risk assessment showed seafloor disturbance caused by fishing occurred in all broad habitat types, 48% of the assessed area in 2016 to 2020, and 53% during 2009 to 2020. ‘High’ disturbance was greatest in Offshore circalittoral mud, alongside Sea-pen and burrowing megafauna communities, whilst disturbance was predominantly ‘Low’ on Offshore circalittoral coarse sediment.

A risk assessment based on available data showed that direct seafloor disturbance caused by aggregate extraction was localised, with less than 0,5% of the area of each habitat disturbed. Sabellaria spinulosa is the only OSPAR Threatened and / or Declining habitat under pressure from extraction but only a small proportion was affected (see also habitat-loss indicator).

Dredging and dumping at sea activities have been well regulated by Contracting Parties since the Oslo Convention came into force in 1974, and then through the OSPAR Convention which came into force in 1998. Since the implementation of the original OSPAR guidelines in 1998, loads of contaminants have decreased and have been levelling since the mid-2000s. Concentrations of many contaminants monitored are considered to be now at, or close to, background concentrations in much of the dredged material.

Habitat loss is caused by sealing and by other activities leading to substrate changes. 92 km² were lost to offshore structures assessed in the Greater North Sea. A risk assessment highlights areas and habitat types most at risk from bottom trawling. Not all structures and activities contributing to loss are covered.