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The white sturgeon (''Acipenser transmontanus'', meaning "sturgeon beyond the mountains"), also known as the Pacific sturgeon, Oregon sturgeon, Columbia sturgeon, Sacramento sturgeon, and California white sturgeon, is a sturgeon (a fish of the family Acipenseridae) which lives along the west coast of North America from the Aleutian Islands to Central California. It is the largest freshwater fish in North America and is the third-largest species of sturgeon, after the beluga and the kaluga. The white sturgeon is known to reach a maximum size of 816 kg (1,799 lb) and 6.1 m (20 ft). The largest sturgeon caught on record was caught on the Fraser River, in British Columbia, and weighed an estimated 1,100 pounds (498.9 kg) and measured 12 feet, 4 inches. The sturgeon was caught by Michael Snell of Salisbury, England, and was later released. ==Physical appearance== The white sturgeon has a slender, long body, head, and mouth. This fish has no scales; instead, it has large bony scutes that serve as a form of armor. The Sturgeon has a very slow grow rate. When the fish is 20 years old it is about 10 inches. Its 11–14 dorsal scutes are all anterior to the dorsal fin, and 38–48 lateral scutes and 9–12 ventral scutes are on each side. The dorsal color of a white sturgeon is gray, pale olive, or gray-brown. The fins are a dusky, opaque gray. The underside is a clean white. It has four barbels, used for sensing food, near its large, toothless mouth. Sturgeons are classified as a bony fish, but actually are more cartilaginous than bony, their internal bone structure being more like a shark's. Sturgeon have changed very little since they first appeared over 175 million years ago, thus have the appearance of a very ancient fish. 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「white sturgeon」の詳細全文を読む スポンサード リンク
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