Seabirds pecking polystyrene items in offshore Adriatic Sea waters

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Why is it important?

A number of seabird species have been known to peck, displace, and ingest various plastic items including expanded polystyrene, for reasons that remain largely conjectural. Ingestion of polystyrene parts potentially causes lethal or sublethal efects on birds. Pecking can also result in the damage of polystyrene items, resulting in increased market turnover and environmental build-up, or economic consequences for stakeholders. In January and February, 2022, fshers in a portion of the western Adriatic Sea coast reported pecking damage caused by gulls (Laridae) to polystyrene buoys used to foat, signal, and retrieve static fshing nets and traps. We investigated the magnitude of this phenomenon in four fshing harbours of Italy by scoring damage to 470 buoys and interviewing 29 fshers (encompassing 42% of the relevant feet). Information was complemented by opportunistic observations at sea. Our preliminary assessment suggests that ofshore polystyrene pecking increases in winter months, and it occurs sporadically among years. The overall economic damage to the static net fshery appeared generally modest (approximately 3–4 Euro to replace one buoy), with wide variations in the extent of reported damage. We reviewed the hypotheses behind polystyrene pecking, but none of them provide a clear explanation for the observed behaviour.