Study Finds Microplastics in Pacific Fish Across Remote Islands

Key points

• A new study detected microplastics in almost one-third of fish sampled across remote Pacific islands, with contamination ranging from 4.8% in Vanuatu to 74.5% in Fiji.
• Fish living on reefs and feeding on the seabed had the greatest contamination levels, especially species that consume small invertebrates.
• Researchers say the widespread presence of synthetic fibres from textiles and fishing equipment underlines the fragility of local food systems in communities where fish is a key source of protein.

Microplastics are now known to be widespread, with an estimated 75 to 199 million tonnes of plastic waste circulating in the world’s oceans and further waste entering waterways every year. Although the issue is already well recognised, a new study illustrates just how alarming the reach of this plastic pollution has become.

In January, researchers published their findings in the journal PLOS One. They examined 878 fish representing 138 species, collected from coastal communities on some of the planet’s most remote islands, including Fiji, Tonga, Tuvalu and Vanuatu. The fish had been caught by local fishers for food before being included in the research.

Microplastics in Pacific fish

The analysis showed that 32.7% of the fish had microplastics in their gastrointestinal tracts, with an average of 0.76 plastic particles per fish. Results differed substantially between countries: 74.5% of the fish sampled in Fiji contained microplastics, while contamination was at midrange levels in Tonga and Tuvalu, at 41.7% and 37.3%, respectively. Vanuatu recorded the lowest rate, with plastics found in only 4.8% of fish.

The study was not designed to establish why Fiji’s figure was markedly higher. However, the researchers pointed to several potential explanations, including a denser population, coastal development, varying waste-management practices and important differences in ocean currents.

Fish found on reefs were significantly more likely to contain plastic than those living in open or deep water. Species that feed along the seabed also had higher contamination than fish feeding at shallower depths. Invertivores - fish that eat small invertebrates including worms and crustaceans - had the highest overall contamination rates.

Synthetic fibres and food-system concerns

The kinds of plastic identified were also significant. In all four countries, microplastic fibres, including fibres shed from textiles and fishing gear, were the most prevalent form, accounting for 66% to 95% of particles identified by the team. Polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET) and nylon were the plastics found most often.

“Beyond the ecological insights, this study delivers a stark warning about the vulnerability of our food systems: we found that the reef-associated and bottom-feeding fish most accessible to our subsistence fishers are acting as reservoirs for synthetic pollution, particularly in Fiji, where nearly three-quarters of sampled individuals contained microplastics,” said Rufino Varea, a researcher at the University of South Pacific and a contributor to this study, in a statement. “The dominance of fibers in these samples challenges the assumption that marine litter is solely a visible, coastal management issue; it indicates a pervasive infiltration of textile- and gear-derived contaminants into the very diet of our communities.”

Eating fish in the age of microplastics

Can you remove microplastics by cleaning fish?
Most of the microplastics identified in this study were in the gastrointestinal tract, which is generally removed before cooking. However, some research indicates that very small particles may still occur in edible tissue.

Is it still safe to eat seafood?
Health specialists still recommend seafood because it provides omega-3 fatty acids and lean protein. Although microplastics are an increasing concern, research into their direct effects on human health is still developing.

Are certain fish more likely to contain microplastics?
Yes. In this study, reef-associated and bottom-feeding fish were more likely to contain plastics, as were species that feed on small invertebrates.

Are farmed fish safer than wild fish?
Microplastics have been detected in both farmed and wild fish. The level of contamination often depends more on local environmental conditions than on whether a fish is farmed.

Although the researchers did not assess what these microplastics may mean for human health, the fish tested were intended for people to eat. As the study notes, fish is a primary protein source for communities throughout the Pacific. Numerous other studies have also indicated possible harmful effects in humans, including an increased risk of major cardiovascular events, inflammation and potential effects on neurological function.

“While microplastic levels in Pacific fish are generally lower than in many industrialized regions, Pacific communities rely far more heavily on fish as a primary protein source,” Amanda Ford, a researcher at the University of South Pacific, added. “Combined with major data gaps across the region, this makes locally generated evidence essential as Global Plastics Treaty negotiations advance and are translated into national policies.”