The walrus (Odobena rosmarus) is certainly one of the most fascinating arctic and enigmatic marine mammal species. It is the enormous size of the animal (it is the largest pinniped in the Northern Hemisphere) and the enormous tusks that attract our attention. Walruses are distributed in the circumpolar Arctic and sub-Arctic regions. The IUCN Red List of Threatened Species listed the walrus in 2016 as ‘vulnerable’ and the WWF estimated the population sizes as >25,000 for the Atlantic, ~200,000 for the Pacific and only ~5,000 for the Laptev walrus.
Traditionally and mostly depending on the region of occurrence, taxonomists listed three subspecies, namely the Atlantic walrus (O. r. rosmarus), the Pacific walrus (O. r. divergens) and the Laptev walrus (O. r. laptevi, originally proposed by Chapskii 1940) that occurs in the Laptev Sea. While there is evidence for differentiation of the Atlantic and Pacific walrus subspecies, it has been debated whether or not the Laptev walrus actually represents a distinct subspecies. Kastelein (2009) refers to the Laptev walrus as dubiously distinct from the Pacific walrus. Based on molecular evidence, Lindqvist et al. (2009) considered the Laptev walrus the westernmost population of the Pacific walrus. This work was conducted as part of the project ‘The Laptev Sea walrus: an enigma revisited‘ at the Natural History Museum Oslo in cooperation with partners from the Norwegian Polar Institute, Tromsø, the
University of Aarhus, Denmark, the Greenland Institute of Natural Resources, Nuuk, Greenland, the
University of Lund, Sweden and the Zoological Institute, Russian Academy of Sciences, Saint Petersburg, Russia, and is also frequently referred to when when claiming that the taxonomic assignment of the Laptev walrus as the authors suggested shall be abandoned. However, one needs to keep in mind that the study by Lindqvist et al. (2009) is based on analyses limited to only four fragments of the mitochondrial genome. More extended future studies may deliver new insights on the taxonomic status of the enigmatic Laptev walrus.
References:
Chapskii, K.K. (1940). Distribution of walrus in the Laptev and East Siberian Seas. Problemy Arktiki 6: 80–94.
Kastelein, R.A. (2009). Walrus, Odobenus rosmarus. In: Encyclopedia of marine mammals. New-York: Academic Press. 1212–1217. 10.1016/B978-0-12-373553-9.00277-7
Lindqvist, C., Bachmann, L., Andersen, L. W., Born, E. W., Arnason, U., Kovacs, K. M., Lydersen, C., Abramov, A. V. & Wiig, Ø. (2009). The Laptev Sea walrus Odobenus rosmarus laptevi: en enigma revisited. Zoologica Scripta 38: 113-127. https://doi.org/10.1111/j.1463-6409.2008.00364.x
