National Performance Framework - Clean Seas Indicator 2017

The Clean Seas Indicator for 2017 is 82.5%. This means that 82.5% of assessments of metals, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in biota and sediment in Scottish marine waters show concentrations that are unlikely to harm marine organisms. The Indicator has increased from its value of 80% in 2015 and 2016 because lead concentrations in sediment in the Minches and Western Scotland are now acceptably low.

The Indicator is calculated by assessing the concentrations of cadmium, lead, mercury, PAHs and PCBs in biota (fish and shellfish) and sediment in four regions: the Northern North Sea, Scottish Continental Shelf, Minches and Western Scotland and Irish Sea (Clyde & Solway). Of the 40 possible assessments, 33 (82.5%) show acceptable concentrations, 2 show unacceptable concentrations and 5 have insufficient data. These are tabulated below with a ✓ indicating acceptable, a ✕ indicating unacceptable, and a blank indicating insufficient data.


compartment region cadmium lead mercury PAHs PCBs
biota Northern North Sea
biota Scottish Continental Shelf
biota Minches and Western Scotland
biota Irish Sea (Clyde & Solway)
sediment Northern North Sea
sediment Scottish Continental Shelf
sediment Minches and Western Scotland
sediment Irish Sea (Clyde & Solway)


The thresholds used to assess whether levels are acceptable differ between contaminants and biota / sediment. Environmental Assessment Criteria (EAC) are used for PCBs in biota and sediment and for PAHs in biota; Effects Range Low (ERL) are used for metals and PAHs in sediment; and European Commission food standards (EC) are used for metals in biota. More information can be found here for biota and sediment.

The raw data used in the assessments can be downloaded here.

Full details of the assessments are available as follows:

These describe the statistical methodology used, and present regional assessments of trends, status with respect to the EAC, ERL or EC, and status with respect to the Background Assessment Concentration, a more stringent threshold used to assess whether concentrations are at background levels.

Regional assessments of other contaminants and biological effects that do not contribute to the Indicator are also available: