Metabarcoding of Walrus scat samples

Between February 2021 and April 2022, a female walrus (Odobenus rosmarus rosmarus), was observed multiple times along the North Sea and Norwegian coasts. Scat samples from the walrus were collected on two occasions when it visited the Dutch Wadden Sea between September and November 2021. It was assumed that the walrus fed locally and to determine the animals' diet, scat samples were analyzed using molecular methods. In both scats, only the Atlantic razor (jackknife) clam (Ensis leei M. Huber, 1843), a mollusk species invasive to the region was found. which invaded the area relatively recently and is very abundant. The walrus did not seem to suffer from the warm water temperature, which reached more than 20°C in summer. We hypothesize that the temperature in the area was not limiting walruses to come south, but potentially overhunting and disturbance. The concurrence of the recovering walrus population in the North East Atlantic and global warming causing loss of sea-ice for haul out and leading to augmenting human pressure in the Arctic might drive increasing walrus visits at lower latitudes in the future. We therefore suggest to draw up adequate management plans to anticipate this.