By John R. Platt
7 May 2015
(Takepart) – For the first time, plastic particles have been found in the stomachs of tuna and other fish that are a staple of the human diet.
More than 18 percent of sampled bluefin, albacore, and swordfish caught in the Mediterranean Sea and tested in 2012 and 2013 carried levels of plastic pollution in their bodies, according to a study published in the journal Marine Pollution Bulletin.
All three species migrate between the Mediterranean and the Atlantic Ocean, so these plastic particles could make their way onto the plates of American consumers. The plastics found in the fish contained phthalates, nonylphenol, bisphenol A, brominated flame retardants, and other chemicals that previous research has linked to endocrine disruption, low reproductive rates, and other health risks.
A 2010 study by French and Belgian marine biologists estimated that 250 billion pieces of microscopic plastic were floating in the Mediterranean. A 2014 expedition by Gabriel Gorsky of Pierre-et-Marie Curie University found that “there is not one parcel of the Mediterranean Sea that is devoid of plastic or plastic fragments.” Another study published last year estimated that all of the world’s oceans combined carry more than 5 trillion pieces of plastic pollution.
The current study of large pelagic fish (which live in the open sea, away from the shores or the bottom of the ocean) examined 56 swordfish, 36 bluefin, and 31 albacore that had been caught in the Mediterranean. Of those fish, seven swordfish, 11 bluefin, and four albacore contained plastics in their stomachs.
The plastics varied in size from large pieces more than 25 millimeters wide to microplastics smaller than 5 millimeters. The swordfish were more likely to have ingested large fragments of plastic, while the albacore ingested mostly microplastics.
Most of the pieces were white or transparent, while some “yellowish” plastics were found in the stomachs of the swordfish and bluefin.
As large, “top of the food chain” predators, the fish could have picked up plastic that had first been eaten by smaller fish; a study published last year found that Mediterranean bogue, an important prey species for swordfish, ingest large quantities of microplastics. The researchers, from the Institute for Environmental Protection and Research in Italy, wrote that other plastics could have been ingested while the tuna chased schools of prey fish into shallow waters, where floating plastics are more abundant. [more]
ABSTRACT: This study focuses, for the first time, on the presence of plastic debris in the stomach contents of large pelagic fish (Xiphias gladius, Thunnus thynnus and Thunnus alalunga) caught in the Mediterranean Sea between 2012 and 2013. Results highlighted the ingestion of plastics in the 18.2% of samples. The plastics ingested were microplastics (<5 mm), mesoplastics (5–25 mm) and macroplastics (>25 mm).
These preliminary results represent an important initial phase in exploring two main ecotoxicological aspects: (a) the assessment of the presence and impact of plastic debris on these large pelagic fish, and (b) the potential effects related to the transfer of contaminants on human health.