Last winter an unusual number of sea turtles beached on the Dutch coast. Some were alive and transported to rehabilitation centres, others however did not survive. Researchers from Wageningen Marine Research got the opportunity to study one of the beached turtles for the presence of ingested plastics, however, the turtles' stomach was found to be completely empty.
In the Mediterranean Sea, sea turtles are used to monitor plastic pollution, comparable with the research on plastic ingestion by northern fulmars conducted in the Netherlands.
Sea turtle stomach analysis at Naturalis
One loggerhead turtle was found dead in April 2024, on the Frisian Wadden Sea coast and was transported to Naturalis Biodiversity Centre. In cooperation with colleagues from Naturalis and Diergaarde Blijdorp where the turtle strandings are monitored, the sea turtle was dissected and its stomach was analysed, which proved to be empty. The loggerhead turtle was found to be an immature female, of around 20 centimetres in size. The animal is added to the collection of Naturalis. The researchers hope that the good cooperation can be continued in the future and, if more animals arrive on Dutch coasts, that these sea turtles can be studied for plastic ingestion.
Previously plastic was found in stomachs of much bigger leatherback turtles, that have been stranded on the Dutch coast. As early as in 1968, researchers reported one piece of plastic in the stomach of a leatherback turtle, found on Ameland. Another leatherback turtle was reported in 1981 from Terschelling, which had ingested a plastic bag.
Rare visitors
Sea turtles occur wherever the water temperature is high enough. The Dutch part of the North Sea is usually too cold for these cold-blooded animals and therefore sea turtles are rarely encountered. Therefore it was quite extraordinary that last winter, several sea turtles stranded on the Dutch coast. The reason for this occurrence remains unclear.
