This bachelor thesis reports on a study conducted at the research institute IMARES in the Netherlands. It focused on plastics ingested by northern fulmars (Fulmarus glacialis) around the North Sea region as a contribution to a better understanding of the fulmar in its role as an indicator for marine litter pollution in European marine policies. The research was divided in two parts. The first part concerned the identification of plastic materials using infrared spectroscopy, and analyses the differences between regions and time periods. Identification of plastic types is not only relevant in the assessment of chemical hazards from ingestion, but it also contributes to the monitoring of fulmars as an indicator for Good Environmental Status (GES) study in the European Marine Strategy Framework Directive (MSFD). Preponderance of floating plastics such as polyethylene and polypropylene indicates that the fulmar is largely a surface pollution indicator, and that indirect secondary ingestion from deeper water layers through fish is less important. The second part of the research looked into the ability of fulmars to grind plastic materials in their stomachs. In a blind test, colleagues were asked to categorize plastic pieces from unknown origin into four categories of ‘wear’. Results provide evidence for gradual grinding of plastics in the muscular stomach. Regional differences in wear suggest that part of plastics seen in stomachs of fulmars from higher latitudes may have been picked up by these birds in more polluted wintering areas. Both study components are new and provide essential building stones for environmental monitoring and associated policy decisions concerning marine debris in European seas and beyond.