Fulmar litter threshold value monitoring in the Netherlands – Update 2020

This report adds new data for year 2020 to the earlier report (Van Franeker & Kühn, 2020). A total of 18 fulmar corpses were collected, of which 15 contained stomachs. Annual numbers of beached birds may vary considerably for unknown reasons. For our monitoring purposes, we do not use birds that have spent more than 3 days alive under human care, because particles break and wear down in the muscular stomach and disappear through the intestines (Van Franeker & Law 2015) and are not replaced by new plastics from the marine environment. In 2020, we did receive some fulmars from rehabilitation centres, but only one had survived more than three days in care, so all but this individual could be used. This means 14 stomachs were available for the 2020 data calculations. No additional fulmars from previous years were analysed. Potential late deliveries can slightly alter earlier published data. The desired annual sample size is ±40 birds or more (Van Franeker & Meijboom 2002). Smaller annual samples, like in 2020, are not a problem for the monitoring system but may delay the detection of significant trends.

The OSPAR long-term target requires an FTV% under 10% for at least 5 consecutive years. Therefore data are also pooled in 5-year periods, as ‘current period’ in Table i. Over the most recent 5 years (2016-2020), in a sample of 139 birds, 39% of stomachs contained more than 0.1 g plastic (FTV%). Although this is (together with the previous period 2015-19) the best FTV-performance in the Dutch monitoring program, it clearly is still far off the OSPAR Fulmar-TV. In this sample, 93% of fulmars contained some plastic, with an average over all birds of 22.5 plastic particles per stomach, weighing 0.21 gram.

The 2020 sample does not continue the decreasing trend seen in the last few years. Although the percentage of birds with plastics remains the same, the average fulmar had 31 plastic particles weighing 0.42 g, and 6 out of 14 birds exceeded the 0.1g level (43%). These figures exceed those of 44 birds in 2019, when the average number of plastic pieces was 11 and the average mass was 0.09 gram per bird. Because of the small size of our 2020 sample it remains unclear if this is an unusual year.
This report includes data on chemical stomach contents, specifically paraffin-like substances for the 
first time. In 2020, 21% of the analysed fulmars contained some paraffin-like substances, on average
weighing 0.041 gram.