Seabird biomonitoring indicates similar plastic pollution throughout the Canary Current

Marine plastic pollution is an emerging global threat for biodiversity. Plastic ingestion is one of the most typical and studied consequences with petrels being a particularly vulnerable group. We studied the plastic ingestion by Cory's shearwater (Calonectris borealis) fledglings in three islands of the Canarian Archipelago (Tenerife, Gran Canaria and Lanzarote). Breeders from different islands show substantial spatial segregation in their foraging areas across the Canary Current Large Marine Ecosystem (CCLME), a critical marine biodiversity hotspot and an important fishing ground in the North Atlantic Ocean. Here, we used a combination of plastic ingestion parameters (number, maximum length, type and colour of plastics) and stable isotopes (δ13C and δ15N) to study potential differences in plastic ingestion loads and trophic niche between three colonies. Our findings reveal a high incidence of plastic ingestion (>90 %) among birds from the three islands. However, although adult birds show foraging and trophic niche segregation across the CCLME, no substantial differences were found in plastic ingestion. White and transparent threadlike fragments were predominantly ingested, likely originating from fishing activities in the CCLME. We provide a baseline for monitoring of plastic pollution in the CCLME and highlight Cory's shearwater as an effective bioindicator of pelagic ecosystems. Our findings emphasize the need for more standardized plastic monitoring programs covering other islands, and for management measures in the fishing activities conducted in the CCLME.