Plastic in Cassin's Auklets (Ptychoramphus aleuticus) from the 2014 stranding on the Northeast Pacific Coast.

Oceanic plastic debris found in the digestive tracts of seabirds includes industrial plastic pellets and post-consumer user plastics. We examined whether the amount and type of plastic ingested by Cassin's Auklets (Ptychoramphus aleuticus) is changing by surveying the stomach contents of 171 Cassin's Auklets stranded along the Washington and Oregon coasts in 2014. We found that 41.5% of the birds contained plastic in their ventriculi, similar to values from the North Subarctic Pacific reported in the 1980s. Industrial pellets were found in 22.8% of our samples, and accounted for 28.1% of all the plastic pieces found. Industrial pellets tended to be larger than pieces of user plastic and accounted for 40.2% of total plastic weight. These industrial pellets were significantly smaller than those found in other species, suggesting either that Cassin's Auklets selected smaller plastic particles or that plastic was retained in ventriculi and worn down.