Microplastics have been discovered in one third of fish species across the coastal waters of Pacific Island Countries and Territories (PICTs), with the highest concentrations of plastic contamination found in fish around Fiji, a new study has revealed.

Published in PLOS One by researchers led by Jasha Dehm at the University of the South Pacific, these findings arrive just as international negotiations on a Global Plastics Treaty are set to resume this year. It’s hoped these talks will renew scrutiny on how plastic pollution is affecting even the most remote marine ecosystems.

Microplastic pollution is a global problem, but Pacific Island nations face distinct vulnerabilities. Rapid urbanisation, expanding coastal development, and limited waste and wastewater management systems have increased the flow of plastic debris into nearshore environments. These same environments underpin food security, livelihoods, and cultural practices across the region, where many communities depend heavily on locally caught fish as their primary source of protein.

Despite these risks, empirical data on microplastic contamination in Pacific fish has been limited.

To address this gap, the research team assessed 878 coastal fish from 138 species caught by fishing communities in Fiji, Tonga, Tuvalu, and Vanuatu, using published records from the Global Information Biodiversity Facility. Across all four countries, around a third of fish contained at least one microplastic particle, but contamination levels varied sharply between islands.

Among the site studied, Fiji stood out. Nearly 75% of sampled fish contained microplastics – far exceeding the global average of 49%. By contrast, only 5% of fish sampled in Vanuatu showed signs of contamination. While the amount of plastic per fish was generally low, the frequency of contamination in Fiji was striking.

Two species – the thumbprint emperor (Lethrinus harak) and the dash-and-dot goatfish (Parupeneus barberinus) – were present in catches from all four countries. Both showed substantially higher contamination rates in Fiji, suggesting that local pressures, rather than species-specific biology alone, are shaping exposure.

Jasha Dehm from the University of the South Pacific, said: “The consistent pattern of high contamination in reef-associated species across borders confirms ecological traits as key exposure predictors, while national disparities highlight the failure of current waste management systems, or lack thereof, to protect even remote island ecosystems.”

To understand why some fish were more affected than others, the researchers analysed ecological traits including diet, habitat, and feeding strategy. Reef-associated and bottom-dwelling species were more likely to contain microplastics than lagoon or open-ocean fish, as were invertebrate feeders, ambush predators, and bottom-feeders.

These ecological patterns have direct implications for Pacific communities, according to the study’s authors, because the most contaminated species are often the most accessible to subsistence and small-scale fishers.

Dr. Rufino Varea from the Pacific Islands Climate Action network, said: “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.”

The study also found that plastic fibres dominated the samples, pointing to sources such as synthetic textiles, fishing gear, and wastewater rather than large, visible debris alone.

“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,” added Varea.

Taken together, the findings challenge the notion that geographic isolation offers protection from plastic pollution. They also raise questions about whether downstream solutions – such as improved recycling – are sufficient to address the scale of the problem.

“This data shatters the illusion that our remoteness offers protection and provides the evidentiary basis we need to reject downstream solutions – such as recycling schemes – as insufficient,” continued Varea.

“Instead, it compels us to demand a Global Plastics Treaty that enforces strict caps on primary plastic production and toxic additives, as this is the only viable way to safeguard the health and food security of Pacific peoples.”

With Global Plastics Treaty negotiations set to re-enter a critical phase this year, the authors argue that evidence from regions like the Pacific must play a central role in shaping outcomes.

Dr. Amanda Ford has emphasised the high stakes for island nations.

“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,” she said. “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.”

As treaty discussions resume, the study serves as a reminder that plastic pollution is not only an environmental issue, but a matter of food security, equity, and long-term health for communities least responsible for producing plastic waste yet among the most exposed to its consequences.

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