Plastic ingestion by North Pacific garbage patch fishes: highest occurrences and quantities in upper trophic pelagics

Abstract

Plastic marine debris (PMD) is rapidly accumulating in the North Pacific Subtropical Gyre, exposing fishes living in the North Pacific garbage patch (NPGP) to extremely high PMD concentrations. We dissected and analyzed the gastrointestinal tract of 204 fish from 13 taxa sampled as bycatch during plastic pollution cleanup operations in the NPGP for plastics >1 mm. Additionally, forty-six prey fish were retrieved from the stomachs of the primary fish and dissected separately to quantify secondary plastic ingestion and potential trophic transfer. A total of 154 plastic items were detected in 56 fishes. Plastics ranged in size from 10 mm to 8.4 cm. Plastic ingestion (frequency of occurrence percent, mean number of particles ± standard deviation (SD)) varied significantly across taxa and was highest in upper trophic pelagic species, including blue sharks (78%, 6.78 ± 2.80 particles/fish) and amberjacks (44%, 1.07 ± 0.34 particles/fish). Moderate plastic ingestion was observed in pygmy sharks (36%, 0.68 ± 0.19 particles/fish), lanternfishes (25%, 0.23 ± 0.06 particles/fish), and flying fishes (9%, 0.47 ± 0.40 particles/fish). There was a single occurrence of plastic ingestion in two of the mid-level predators (cookiecutter shark and sargassumfish) and no plastic ingestion by two lower trophic reef-associated species (fang blenny and Indo-Pacific sergeant fish).