Observations of investigations for plastic ingestion in loggerhead turtles (Caretta caretta), stranded or bycaught on the coastline of North Cyprus (Eastern Mediterranean). A total of 135 loggerhead turtles were sampled spanning a period of 11 years (2012-2022). During necropsy, the entire gastrointestinal tract was removed and initial contents weighed. The contents were grossly examined then rinsed through a 1 mm mesh sieve to separate and remove the plastic for classification and dietary items for storage and analysis. Ingested plastic was classified using a system outlined in Duncan et al. (2019, doi:10.1038/s41598-019-48086-4; 2021, doi:10.3389/fmars.2021.699521) which builds upon the Fulmar Protocol and MSFD (Marine Strategy Framework Directive) Marine Litter Report 2011 (Descriptor 10) toolkits (Galgani et al., 2014, doi:10.1016/j.marenvres.2014.02.003; van Franeker et al., 2011, doi:10.1016/j.envpol.2011.06.008).

Types of plastic (She, Thr, Foam, Frag, Poth, Ind): The type of plastic debris: Industrial plastic pellets or nurdles (IND) and user plastics (USE) which can be split into several sub-categories; sheetlike plastic (SHE e.g., plastic bags), threadlike/filamentous plastic (THR e.g., remains of rope), foamed plastics (FOAM e.g., polystyrene), fragments (FRAG e.g., hard plastic pieces) and other (POTH, e.g., rubber, elastics, items that are 'plastic-like', not clearly fitting into another category). Taken from Fulmar Protocol and MSFD (Marine Strategy Framework Directive) Marine Litter Report 2011 (Descriptor 10) toolkits. Counts observed in specific individual turtle. Colours of plastic: (Clear, White, Pink/Purple, Red, Orange, Yellow, Green, Blue, Bown, Black, Grey) Colour was recorded within 11 categories. Counts observed in specific individual turtle.