Microplastics Found In Spotted Seals Of Remote Alaska

Research conducted recently by the Plastic Waste University of Alaska Fairbanks has shown that spotted seals in some of the most isolated marine areas in Alaska are ingesting high quantities of microplastics as part of their diets. The result contradicts the image of the Arctic as a pristine environment and indicates the extensive influence of plastic contamination, even in remote ecosystems.

The research, published in Marine Pollution Bulletin, compared the stomach contents of spotted seals taken by subsistence hunters in the Bering and Chukchi seas. Just one of the 34 seal stomachs was microplastic-free. The specimens contained a total of 190 microplastic particles, with no contamination differences related to age, location, or year of harvest.

The study targeted seals harvested in 2012 and 2020 from the Gambell and Shishmaref communities in Alaska. Alexandria Sletten, the lead author of the study, carried out the project as part of her graduate work at the UAF College of Fisheries and Ocean Sciences. Sletten says the study indicates that microplastic pollution has been in the seals' diets for more than a decade.

"Most individuals perceive the Arctic as this untouched place that's not contaminated with anthropogenic stuff," Sletten said. "But microplastics have been present in this environment, and marine mammals are consuming it."

The sources of microplastics in such distant places are still uncertain, but marine currents are significantly responsible for spreading them across the globe. Also, sea ice, which is known to be highly contaminated with microplastics, discharges these particles into the ocean during melting.

Microplastics have been found with greater frequency in marine animals and even in human tissues, sparking concern about their possible health effects. Some plastic polymers have been associated with negative health consequences, but little is known about the long-term effects of microplastic consumption in marine mammals.

The research indicated that microplastics were found most commonly in the stomachs of seals who had eaten shrimp and sculpin, types of fish which live on the sea floor where plastic particles collect. Higher-ranking fish species in the food chain, including saffron cod and pollock, also showed significant amounts of microplastics.

This study is the first time that stomach content of marine mammals has been examined for microplastics in the Chukchi and Bering seas, yet it follows a pattern seen in Arctic wildlife more widely. Lara Horstmann, associate professor of marine biology at UAF and co-author on the study, has already reported finding microplastics in various marine mammals throughout the Arctic and sub-Arctic.

“We found it everywhere,” Horstmann said. “It’s been in all of the tissues we’ve looked at so far. There’s nothing that’s absolutely clean and pure out there.”

Her previous research has detected microplastics in the tissues of bowhead whales, bearded seals, beluga whales, northern fur seals, and walruses. The particles have been found in placentas, amniotic fluid, livers, and muscle tissues, indicating extensive contamination throughout the marine food web.

The research could not have been conducted without the cooperation of local subsistence hunters, who donated the seal samples as part of an ongoing biomonitoring effort led by the Alaska Department of Fish and Game. The cooperation highlights the value of indigenous knowledge and community participation in scientific research, especially in areas that are remote and ecologically valuable.

As plastic pollution continues to permeate the world's oceans, its discovery in the Arctic's marine life is a harrowing reminder of the ecological threats brought about by human actions. Though it is still unclear what the complete effects of microplastic consumption will be on marine mammals, research such as this one sheds important light on how pollution is seeping into even the most seemingly unimpacted ecosystems.