Spotted seals in some of the most remote marine areas around Alaska are consuming significant amounts of microplastics in their diets, according to a new University of Alaska Fairbanks–led study.

The paper, published in the current issue of Marine Pollution Bulletin, analyzed the stomach contents of spotted seals harvested by subsistence hunters in the Bering and Chukchi seas. Of the 34 seal stomachs that were examined, only one had contents that were free of microplastics.

The study focused on specimens from 2012 and 2020 that were harvested in the Alaska communities of Gambell and Shishmaref. A total of 190 microplastics were found in the seal stomachs, appearing in concentrations that did not vary by age, location or the year they were harvested.

Alexandria Sletten, who led the project while pursuing her graduate degree at the UAF College of Fisheries and Ocean Sciences, said the findings indicate that similar levels of microplastic contamination have been in the seals’ diets since at least 2012.

“Most people view the Arctic as this pristine location that’s free of this anthropogenic contamination,” said Sletten, the lead author of the study. “But microplastics have been in this environment, and marine mammals are ingesting it.”

The specific source of microplastics in such remote areas is unknown, but ocean circulation has contributed to their spread throughout the world. Research has also shown that sea ice is heavily polluted with microplastics, releasing it into the ocean when it melts.

The presence of microplastics in animals and people is a growing concern, and some plastic polymers have been linked to a variety of health problems.

The highest levels found in the spotted seal stomachs were in prey like shrimp and sculpin, which live on the sea floor where microplastics accumulate, and in fish species  like saffron cod and pollock that are higher on the food web.

The study is the first to analyze stomach contents from marine mammals in the Bering and Chukchi seas, but its findings are just the latest in a consistent pattern. Research led by Lara Horstmann, an associate professor of marine biology at the UAF College of Fisheries and Ocean Sciences, has found microplastics in numerous marine mammals in the Arctic and sub-Arctic. The pollutants have also been found in tissues of bowhead whales, bearded seals, beluga whales, northern fur seals and walruses. The plastics were detected in placentas, amniotic fluid, livers and muscle tissue.

“We found it everywhere,” said Horstmann, who also contributed to the spotted seal study. “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.”

Horstmann credited subsistence hunters in the region for making the spotted seal study possible. The specimens were donated to the Alaska Department of Fish and Game as part of a long-term biomonitoring project.

UAF

  Alaska, contamination, diets, micrplastics, seals