Anthropogenic food resources, sardine decline and environmental conditions have triggered a dietary shift of an opportunistic seabird over the last 30 years on the northwest coast of Spain

Calado, J.G., Paiva, V.H., Ramos, J.A., Velando, A. & Munilla, I., 2020. Anthropogenic food resources, sardine decline and environmental conditions have triggered a dietary shift of an opportunistic seabird over the last 30 years on the northwest coast of Spain. Regional Environmental Change, 20(1), p.10.


Human activities and environmental conditions are the main drivers of ecosystem change. One major alteration near the western Iberian coast has been the collapse of the Atlanto-Iberian sardine Sardina pilchardus stock, with important cascading effects on marine top predators. We investigated the effect of long-term changes in fishery landings, sardine availability and environmental conditions on the diet of the yellow-legged gull Larus michahellis in the northwest coast of Spain, over the last 30 years (1987–2017). Dietary trends of gulls were investigated through the analysis of 5010 pellets that revealed a sharp decline of fish and refuse and a shift to a crustacean-based diet. General additive mixed models showed that both total fish and sardine occurrences in gull pellets were negatively associated with total fishery landings and positively associated with sardine landings, suggesting fish depletion and higher fishing efficiency (i.e. reduced discards) during the study period. The winter North Atlantic Oscillation (NAO) index was also positively related with sardine occurrence in gull pellets, possibly due to low sardine abundance and rough conditions in years with very low NAO values. The refuse decline was most probably caused by the closure of open-air landfills, implemented under the European Union Landfill Directive. Our results suggest that changes in fishing practices and waste disposal were the main factors responsible for the sharp decline of fish and refuse in yellow-legged gull diet.

The use of European shag pellets as indicators of microplastic fibers in the marine environment

Álvarez, G., Barros, Á. and Velando, A., 2018. The use of European shag pellets as indicators of microplastic fibers in the marine environment. Marine Pollution Bulletin, 137, pp.444-448.

Microplastic particles are abundant marine pollutants that are ingested by many seabirds. Some seabirds regurgitate non-digestible materials in the form of pellets and their analysis may be useful to study the abundance of plastic debris at the local scale. Here, we aimed to provide baseline data for the presence of microplastics in pellets regurgitated by European shags (Phalacrocorax aristotelis) (n = 41) in the Iberia peninsula (NW Spain). We found microplastic fibers in 63% of pellets, suggesting that this type of plastic pollution is prevalent in the study area. According to Fourier Transform Infrared spectrometry, nylon fibers were the most abundant, followed by polyester. We also found that the presence of microplastics was higher in pellets containing remains of benthic fishes. Our results suggest that shag pellets may be useful to monitor microplastic pollution in coastal waters.