Evidence of microplastic ingestion in ringed seals (Pusa hispida) from the Canadian Arctic

Ringed seals (Pusa hispida) play a crucial role in Arctic marine food webs, serving as predators of fish and invertebrates, and as prey for polar bears (Ursus maritimus). They are also a critical food source for Inuit subsistence. However, there is limited data on microplastic accumulation in Arctic pinnipeds, including ringed seals. To better understand the extent of ingestion and potential accumulation of microplastics in ringed seals from the Canadian Arctic, 30 ringed seal stomachs were collected in collaboration with Inuit Hunters from Arviat and Resolute Bay, Nunavut, Canada, in 2021. All suspected microplastics underwent analysis by Raman microspectroscopy to identify polymer type, and all identified microplastics were counted and categorized based on size, color and morphology. Microplastics were present in 23 out of 30 (77%) seal stomachs, with abundances ranging from 0 to 6 particles per seal (mean = 2.0 ± 1.6 pcs/seal). Fragments were the most prevalent morphology identified (55%), followed by fibers (42%) and films (3.3%). Most particles were unidentified anthropogenic particles and polyester fibers. Microplastic abundances were similar between sexes and between seals collected from the two locations, and no relationships were found between microplastic abundances and age or any morphometric measurements. This study provides new data confirming the presence and characteristics of microplastics ingested by ringed seals harvested in Arviat and Resolute Bay, Nunavut, Canada, and provides baseline information for future plastic pollution monitoring programs in the region.