Evidence for non-selective ingestion of microplastic in demersal fish

Microplastics have been observed in >100 species of fish, with considerable variability in levels of contamination in different species and different geographic locations. Here, we investigated the incidence of microplastic in five species of demersal fish (four wild-caught species and one from a mariculture business) in Hong Kong. We observed that 54% of fish stomachs contained microplastic (hard fragments and fibres) with no significant difference in the abundance of microplastic ingested between the species, between wild and commercial fish farms, or between locations. In addition, we observed no difference between the type of microplastics (shape or composition) ingested by fish. However, we did observe spatial variation, with fish closest to the Pearl River having higher frequency of occurrence of microplastics which reinforce the evidence that fish collected close to urban area are more likely to ingest microplastics.