Short-tailed shearwater (Ardenna tenuirostris) plastic loads and particle dimensions exhibit spatiotemporal similarity in the Pacific Ocean.

Short-tailed shearwater (Ardenna tenuirostris) stomach contents provide some of the earliest documentation of oceanic plastic pollution, one of the longer data series of seabird stomach samples, and the species' wide range in the North and South Pacific provides comparative data for the Pacific Ocean. A mortality event in the North Pacific in 2019 provided additional data for spatiotemporal comparisons. In the North Pacific the percent occurrence, mass, and number of pieces were similar since the first records in the 1970s. Particle size increased slightly reflecting a transition from uniform pre-manufactured pellets in initial reports to irregular user fragments in recent reports. Contemporary North and South Pacific plastic loads and particle dimensions were similar. A lack of temporal or spatial difference affirms previous conclusions that plastic retained in short-tailed shearwaters and other Procellariiformes is related to body size, gastrointestinal structure, and species' preferences rather than the availability of oceanic plastic.

Long-term changes in the type, but not amount, of ingested plastic particles in short-tailed shearwaters in the southeastern Bering Sea.

We report the current (1997-1999, 2001) incidence and amount of ingested plastic in short-tailed shearwaters (Puffinus tenuirostris) in the southeastern Bering Sea and compare our results with plastic reported in shearwaters during 1970-1978. We also examine correlations between plastic loads and shearwater body mass. We found that 84% (N = 330) of shearwaters sampled in 1997-1999 and 2001 contained plastic. The incidence and amount of ingested plastic have not significantly changed since the 1970s. In contrast, the predominant type of plastic has changed over time, from industrial plastic to user plastic. S,asonal patterns in the incidence and amount of ingested plastic also changed from peak levels during early and late summer in the 1970s to mid summer in the late 1990s and 2001. We suggest that the availability of neuston plastic to seabirds in the Bering Sea has undergone a shift in composition since the 1970s. Shearwater body mass appears little if at all impaired by plastic, at least at present levels of consumption.