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The Siberian sturgeon (''Acipenser baerii'') is a species of sturgeon in the Acipenseridae family. It is most present in all of the major Siberian river basins that drain northward into the Kara, Laptev and East Siberian Seas, including the Ob, Yenisei (which drains Lake Baikal via the Angara River) Lena, and Kolyma Rivers. It is also found in Kazakhstan and China in the Irtysh River, a major tributary of the Ob. The species epithet honors the German Russian biologist Karl Ernst von Baer. ==Taxonomy== Siberian sturgeon is typically divided into two subspecies.〔 However, recent studies suggest they may be monotypic, forming continuous genetically connected populations throughout their vast range.〔Ruban, G.I. (1999). (Siberian Sturgeon Acipenser baerii Brandt (Structure and Ecology of the Species) ). Moscow. GEOS publishers. Pp. 235 (in Russian).〕 The nominate taxon (''A. b. baerii'') accounts for 80% of all Siberian sturgeon and resides in the Ob River and its tributaries. This subspecies migrates to mouth of the Ob during the winter due to seasonal oxygen deficiency, and swims thousands of kilometers upstream to spawn. The subspecies ''A. b. baicalensis'', known as the Baikal sturgeon, is a unique lake form found primarily in the northern end of Lake Baikal and migrates up the Selenga River to spawn. Once considered a third form, "''A. b. stenorrhynchus''" resides in the eastern Siberian rivers and displays two life history patterns: a more abundant migratory one which swims considerable distances (sometimes thousands of kilometers) upstream from estuaries and deltas to spawn, and a nonmigratory form. This form is now considered to be a junior synonym of ''A. b. baerii''. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Siberian sturgeon」の詳細全文を読む スポンサード リンク
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