Setting the scene: Should we expect small pelagic fish to ingest plastic pellets?

We investigated the ingestion of preproduced plastic pellets (<3 mm), also known as nurdles, by mesopelagic teleost fish following an industrial spill near the eastern Cantabrian continental shelf. We analyzed 228 specimens from seven pelagic fish species but found no pellet ingestion. The absence of plastic ingestion is likely due to several factors, including low pellet concentrations in the sampling area, their high buoyancy keeping them beyond the fish feeding zone, or species-specific feeding selectivity. The findings of this study suggest a low occurrence of plastic pellets in the stomachs of mesopelagic fauna, though ingestion may be more likely in areas with higher pellet concentrations. This study provides a baseline for assessing mesopelagic species' responses to future plastic pellet spills. • No plastic pellets were found in 228 mesopelagic fish from seven species. • High pellet buoyancy likely prevents ingestion by pelagic fish. • Pellet absence suggests low local pollution or feeding selectivity. • Plastic pellets were absent from fish stomachs despite being within the prey size range. • The study provides a baseline for future plastic pellet spill assessments.