How bottom feeding species are exposed to plastic pollution
Inuit have been hunting walruses for centuries, and walrus continue to be an important country food to northern communities, especially those in the Canadian Arctic. In communities across Nunavut, walrus meat is shared by community members and, as highlighted in the Government of Nunavut’s Nutrition Fact Sheet Series for Inuit Traditional Foods, is an excellent source of protein, iron, zinc, omega-3 fatty acids and selenium. In some communities, such as Igloolik and Sanirajak, walrus meat and blubber are carefully aged in walrus skins for months in gravel caches on the land. The fermented walrus meat (igunaq) is shared among communities and is considered a treat by many.
Threats to walrus populations have recently been identified, including pollution and changing food webs. To understand how changes in the environment are affecting walrus populations, the Department of Fisheries and Oceans (DFO) has been working with communities to sample walrus by working collaboratively with hunters during the seasonal harvests in Nunavut. Cory Matthews and his team from DFO have been working with communities to sample walrus meat, blubber, skin, organs, whiskers, and tusks. Each year sampling kits are shared with Hunters and Trappers Association and Organization (HTAs and HTOs) offices, and Inuit hunters collect the samples while processing the animals for community sharing. This community‐based sampling program has been running for several decades and has provided a valuable tissue sample archive for studying walrus populations over that time.
In 2020, DFO partnered with Environment and Climate Change Canada (ECCC) to address concerns about microplastics and plastic associated contaminants in walruses in Nunavut. Microplastics are pieces of plastics that are smaller than 5 mm and are of concern in the Arctic because when microplastics are ingested, they can have negative effects on animals. Previous studies on plastic pollution in Nunavut in collaboration with HTOs have shown that some species can ingest and accumulate plastic pollution. For example, several seabird species that feed at the surface (e.g., fulmars and kittiwakes) can accumulate plastics in their stomachs, while other species that feed in the water column have not been found to accumulate plastic pollution (e.g., eiders and ringed seals). One study on beluga whales in the Inuvialuit Settlement Region found only very small micro fibers in seven whales sampled by hunters. These microplastics were all smaller than 0.5 mm, and thus likely don’t accumulate in stomachs of the animals but demonstrate that microplastics can be found in a range of species.
As we learn more about how common plastic pollution is in the North, several communities have voiced concerns about other species, particularly those that are benthic feeders, like walrus. In 2020, when many research programs across Canada were cancelled or minimized due to the COVID‐19 pandemic, the walrus sampling program was expanded as compared to previous years. In collaboration with local HTAs and HTOs, community‐based coordinators were hired in several Nunavut communities to help promote the sampling program among walrus hunters.
Walrus stomach and tissue samples collected in 2020 will be used to study both diet and contaminants. The stomachs will be opened, and all contents will be sifted to examine ingested microfibers and microplastics down to 20 μm. Meat and blubber will also be examined for contaminants that are known to come from plastic pollution. Because walruses are bottom feeders, using their tusks to dig up clams and other benthic organisms, this study will help us understand how bottom feeding species may be exposed to plastic pollution.
By combining the work that DFO is leading on diet with partners at the University of Manitoba, and the plastic pollution analysis supported by ECCC with partners at Carleton University, the goal is to assess diet and contaminants in each animal, and report back this information to communities. If you would like to learn more about community‐based walrus sampling and research in your community, please contact your local HTO or HTA, or Cory Matthews (Cory.Matthews@dfo‐mpo.gc.ca) or Jennifer Provencher (Jennifer.Provencher@canada.ca).