Since 1997 each winter period areas in the Dutch North Sea has been monitored on the occurrence of oil pollution in seabirds by members of NIOZ and the Dutch Seabird Group.
Species-specific oil rates (proportion of birds oiled) reflect the risk for various species of marine birds to become oiled at sea. High oil rates occur particulalry in seabirds that are most common in areas with oil spills and whose behaviour (swimming and diving) puts them at particular risk.
A wide array of seabirds are monitored on oil contamination. Among these, because of its abundance, wide distribution and wing-propelled pursuit foraging mode, the common guillemot was selected as an appropriate representative for a closer examintion of annual trends in seabird pollution. The occurrence of oil on carcasses of guillemots washing ashore appeared to have steadily decreased over the last decades (Camphuysen 2017, Monitoring and assessment of the proportion of oiled Common Guillemots from beached bird surveys in The Netherlands: annual update winter 2015/16).
Continued financial support for monitoring and reporting until 2020 has now been provided by Rijkswaterstaat. This enables resaearchers to investigate if the decline in oiled birds will continue, as was predicted in the above mentioned report (Camphuysen 2017).