The method of age determination of the Pacific walrus (Odobenus rosmarus divergens) using the layered structure of functional teeth
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The functional teeth of Pacific walruses that died or were harvested in the Retkyn Spit, Enmelen village, Kolyuchin Island, Vankarem Cape, Enurmino village, and Chegitun River region in 2005, 2007–2008, and 2010–2011 were examined. The definite structure was investigated in animals of their first year of life. The presence of a milk layer in the tooth dentine can be considered as a mark that all the cement layers have been preserved, and the age determination of an individual is precise. The annual increment of dentine significantly changed with age in different parts of the tooth (buccal, lingual, and central), and the annual growth of dentine decreased every year. The growth rate of the upper jaw teeth was significantly higher, and the duration of their growth was much longer than that in the lower jaw teeth. The wearing of dentine and cement layers was unequal in different parts of tooth. Several recommendations for choosing a tooth for the determination of the walrus’s age and for the estimation of age using the layered tooth structure are given.
Keywordsage determination growth rate of teeth wearing of teeth annual dentine layer pinnipeds walrus Odobenus rosmarus
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- Bukhtiyarov, Yu.A., On causes of decline in the Pacific walrus population, in Rezul’taty issledovanii morskikh mlekopitayushchikh Dal’nego Vostoka v 1991–2000 gg (Results of Studies on Marine Mammals in the Far East, 1991–2000), Moscow: VNIRO, 2001, pp. 68–75.Google Scholar
- Dannye o rezul’tatakh issledovanii lastonogikh i kalana v Severnom, Kaspiiskom i Tikhookeanskom basseinakh (promezhutochnyi otchet), (Data of Studies on Pinnipeds and Sea Otter in the Northern, Caspian, and Pacific Basins: Progress Report), Moscow: VNIRO, 1979.Google Scholar
- Fay, F.H., Ecology and biology of the Pacific walrus, Odobenus rosmarus divergens Illiger, North American Fauna, 1982, no. 74.Google Scholar
- Freiman, S.Yu., Materials on the biology of Chukchi walrus, Izv. Tikhook. Inst. Rybn. Khoz. Okeanogr., 1941, vol. 20, pp. 3–20.Google Scholar
- Kibal’chich, A.A., Predatory walruses, in Morskie mlekopitayushchie. Tezisy dokladov 9 Vsesoyuz. soveshchaniya po izucheniyu, okhrane i ratsional’nomu ispol’zovaniyu morskikh mlekopitayushchikh (Marine Mammals: Abstr. 9th All-Union Conf. on the Study, Protection, and Rational Management of Marine Mammals), Arkhangel’sk, 1986, pp. 182–183.Google Scholar
- Klevezal, G.A., Registriruyushchie struktury mlekopitayushchikh v zoologicheskikh issledovaniyakh (Recording Structures of Mammals in Zoological Research), Moscow: Nauka, 1988.Google Scholar
- Klevezal, G.A. and Kleinenberg, S.E., Opredelenie vozrasta mlekopitayushchikh (po sloistym strukturam zubov i kosti) (Determining the Age of Mammals by Lamellar Structures of Teeth and Bones), Moscow: Nauka, 1967.Google Scholar
- Krylov, V.I., Ade determination, growth rate, and age structure of the Pacific walrus piopulation, in Morskie mlekopitayushchie (Marine Mammals), Moscow: Nauka, 1965, pp. 201–211.Google Scholar
- Kryukova, N.V., Dentition in Pacific walruses (Odobenus rosmarus divergens) calves of the year, Zool. Zh., 2011, vol. 90, no. 11, pp. 1385–1394.Google Scholar
- Mansfield, A.W., The biology of the Atlantic walrus, Odobenus rosmarus rosmarus (Linnaeus) in the eastern Canadian Arctic, Fisheries Research Board of Canada Manuscript Report Series (Biology), no. 653, 1958.Google Scholar