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Northern pikeminnow
The northern pikeminnow, or Columbia River dace (''Ptychocheilus oregonensis'') 〔
〕 is a large member of the minnow family, Cyprinidae.〔
〕 Until 1999, when the American Fisheries Society officially changed the common name to pikeminnow, the four species of this genus were known as squawfish. Female northern pikeminnow reach sexual maturity at about six years, males in three to five. They can live longer than 15 years, reaching over 24 inches and eight pounds. The current world record weight for the pikeminnow, 13½ pounds, is held by Christopher Borger and Michael Ray of Edmonton, Alberta. A mature female can lay 30,000 eggs annually. Pikeminnow are voracious predators, and in the Columbia and Snake Rivers, salmon smolts comprise a large part of their diets. Their populations have flourished with the development of the Columbia River hydropower system.〔Mesa, M. 1994. Effects of multiple acute stressors on the predator avoidance ability and physiology of juvenile chinook salmon. Transactions of the American Fisheries Society 123:786–793.〕 The reservoirs have provided excellent habitat for pikeminnow and given them an advantage over depressed salmon and steelhead populations.〔Petersen, J. 1994. Importance of spatial pattern in estimating predation on juvenile salmonids in the Columbia River. Transactions of the American Fisheries Society 123:924–930.〕 While historically pikeminnow have not been of interest commercially nor to sport anglers, Washington and Oregon state fisheries agencies and the Bonneville Power Administration have placed a bounty〔(Pikeminnow Bounty Program )〕 on them to reduce predation on scarce salmon stocks. A sport fishery has developed based on that bounty.
== References ==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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