Microplastics Found in UK Estuary Fish: New Study Reveals Clear Contamination Data
London, UK - 09/12/2025
New research published in Science of the Total Environment shows that 41.5% of commercially important fish sampled from two UK estuaries had ingested microplastics, providing clear evidence that plastic pollution is present in UK waters.
Researchers analysed 53 fish from three commercially harvested species (European flounder, whiting and Atlantic herring) collected from the River Thames and the River Stour in East Anglia. Overall, 37.5% of flounder, 52.2% of whiting and 28.6% of herring were found to contain at least one microplastic particle.
Figure 1 and 2 show the River Thames and the River Stour in East Anglia the study locations where the fish were sampled.
Microplastics are plastic particles smaller than five millimetres and originate from sources such as synthetic clothing fibres, household waste and the breakdown of larger plastic items. The average number of microplastics per fish ranged from 1.47 to 2.46 particles depending on species.
The study found that plastic fibres were the most common type of microplastic identified. Polypropylene accounted for 61% of all particles found, followed by polyethylene at 25%. Larger fish generally contained more microplastics than smaller individuals.
All fish species examined are sold for human consumption. While the effects of microplastics on human health are still being researched, plastics are known to carry harmful chemicals and microorganisms, raising concerns about long-term impacts on ecosystems and food safety.
Dr Alice Horton, one of the lead authors, stated:
“Our data show that microplastics are present in a large proportion of commercially important fish in UK estuaries. Reducing plastic waste entering rivers is crucial to protect aquatic environments and the species that depend on them.”
This research highlights how deeply plastic pollution has become
embedded in UK aquatic environments and underlines the
importance of reducing plastic waste at its source to protect rivers,
wildlife and the food we eat.
Libby Stevens
University of Plymouth
Figure 3 shows microplastics under a microscope (Irvine, 2023)
Key Information
- 41.5% of fish sampled contained microplastics
- Flounder: 37.5% contaminated
- Whiting: 52.2% contaminated
- Herring: 28.6% contaminated
- Most common plastics: Polypropylene (61%)
and Polyethylene (25%)