It's a long way to the Arctic: First record of plastic debris in the stomach of a hooded seal pup in the Greenland Sea

In April 2017, we conducted a cruise in the Greenland Sea, on board of the RV “Helmer Hansen”. The main objective was to collect tissue samples of hooded seal (Cystophora cristata) pups, during the post-weaning fast. Four hooded seals (1 male, 3 females) were sampled. Hooded seals’ length ranged between 93 and 105 cm. We estimated the pups to be ± 20 days old. We examined the digestive apparatus of all pups for the presence of prey and/or milk. Most stomachs and intestines were empty, except for hooded seal pup #H1-17 that contained milk at the end of the small intestine, and #H5-17, which contained three semi-digested shrimps (possibly Themisto spp.) and five pieces of plastic debris in its stomach. The latter consisted of buoyant, light-plastic pieces, originating from a larger food package from a well-known food manufacturing company. Their length ranged from 0.03cm to 11.2cm, their width ranged from 0.08cm to 7.0cm. Hooded seals from the Greenland Sea stock give birth in the pack ice in late March. Two-three weeks after weaning, pups start searching for food at the outer edge of the pack ice. During the first excursions, blueback pups focus on ice-associated crustaceans such as Themisto spp. The presence of plastic debris in one of the pups, however, was rather surprising. Many observations exist of Arctic animals (seabirds, sharks, whales) ingesting plastic debris. Plastic reaches the Northeastern Atlantic and the Arctic Ocean from highly populated southern latitudes via the Gulf Stream. In our case, the plastic debris seem to derive from a distribution site in Texas. Mysticetes may accidentally ingest floating material along with prey species when filter feeding. Seabirds may actively feed on plastic due to the resemblance with their normal prey. On the contrary, seals that feed selectively on fish, crustaceans and deep-water cephalopods have not been recorded to feed on plastic debris until now. To our knowledge, this is the first record of plastic ingestion by a phocidae species in the Arctic. The decrease in ice cover and thickness, as well as a dramatic increase in the use and expel of human made plastic during the last decades may have increased plastic scattering at the water surface of the Arctic Ocean. Increased availability of plastic, even in the remote areas of the pack ice, may currently increase the risk of plastic being eaten by unexperienced, hungry seal pups.SODYMAR