Microplastics in fish and fishmeal: an emerging environmental challenge?

• Published in: Scientific reports Vol. 11; no. 1; p. 2045
• Main Authors: Thiele, Christina J., Hudson, Malcolm D., Russell, Andrea E., Saluveer, Marilin, Sidaoui-Haddad, Giovanna
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21.01.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 704/172; 704/829; Aquaculture; Aquaculture feeds; Biota; By products; Consumption; Contaminants; Contamination; Fisheries; Food contamination & poisoning; Humanities and Social Sciences; Identification; Marine aquaculture; Marine fish; Microplastics; multidisciplinary; Oceans; Plastic debris; Plastics; Pollution control; Polyethylene; Polymers; Science; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-81499-8

Microplastics are contaminants of emerging concern; they are ingested by marine biota. About a quarter of global marine fish landings is used to produce fishmeal for animal and aquaculture feed. To provide a knowledge foundation for this matrix we reviewed the existing literature for studies of microplastics in fishmeal-relevant species. 55% of studies were deemed unsuitable due to focus on large microplastics (> 1 mm), lack of, or limited contamination control and polymer testing techniques. Overall, fishmeal-relevant species exhibit 0.72 microplastics/individual, with studies generally only assessing digestive organs. We validated a density separation method for effectiveness of microplastic extraction from this medium and assessed two commercial products for microplastics. Recovery rates of a range of dosed microplastics from whitefish fishmeal samples were 71.3 ± 1.2%. Commercial samples contained 123.9 ± 16.5 microplastics per kg of fishmeal—mainly polyethylene—including 52.0 ± 14.0 microfibres—mainly rayon. Concentrations in processed fishmeal seem higher than in captured fish, suggesting potential augmentation during the production process. Based on conservative estimates, over 300 million microplastic particles (mostly < 1 mm) could be released annually to the oceans through marine aquaculture alone. Fishmeal is both a source of microplastics to the environment, and directly exposes organisms for human consumption to these particles.