Preliminary evidence of delayed spawning and suppressed larval growth and condition of the major carps in the Yangtze River below the Three Gorges Dam
Preliminary evidence of delayed spawning and suppressed larval growth and condition of the major carps in the Yangtze River below the Three Gorges Dam
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DOI：
10.1007/s10641-011-9934-8
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发表时间：
2012-02
影响因子：
1.4
通讯作者：
Guo Zhang;Lang Wu;Hong-tao Li;Ming Liu;Fei Cheng;B. Murphy;S. Xie
中科院分区：
文献类型：
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作者：
Guo Zhang;Lang Wu;Hong-tao Li;Ming Liu;Fei Cheng;B. Murphy;S. Xie
三峡大坝建成后，长江中下游主要鱼类（草鱼、银、青鱼和鳙鱼）的经济渔获量急剧下降。为了评估特定的环境效应，2007年6月至8月期间，在长江监利（幼鱼）和鄂州（幼鱼）和洞庭湖（幼鱼）的TGD以下收集了2007年的主要鲤鱼。对耳石进行分析以确定早期生长。有没有明显的增长增量耳石的大多数幼虫（38的63草鱼和40的47银鲤），而增量是明显的耳石形成的幼虫阶段的所有青少年，表明幼虫没有明显的增量未能招募到少年阶段。主要鲤鱼的孵化期在5月31日至7月24日之间。与TGD前的记录相比，产卵季节的开始推迟了约1个月。幼鱼的生长率，反映了耳石增量宽度，洞庭湖（接近TGD）比鄂州（远离TGD），表明TGD调节的早期生长和发育的鱼类孵化更接近大坝更明显。长江中下游主要鲤鱼资源近年来呈下降趋势，其原因可能与产卵延迟和早期生长下降有关。
Commercial catches of the ‘major carps’ (grass carpCtenopharyngodon idella, silver carpHypophthalmichthys molitrix, black carpMylopharyngodon piceusand bighead carpAristichthys nobilis) in the middle and lower reaches of the Yangtze River have declined precipitously since construction of the Three Gorges Dam (TGD). To assess specific environmental effects, young-of-the-year major carps were collected below TGD in the Yangtze River at Jianli (larvae) and E’zhou (juveniles) and in the Dongting Lake (juveniles) during June–August 2007. Lapillar otoliths were analyzed to determine early growth. There were no discernible growth increments in otoliths for a majority of the larvae (38 of 63 grass carp and 40 of 47 silver carp), while increments were evident in otoliths formed in the larval stage for all the juveniles, indicating that larvae without discernible increments failed to recruit to the juvenile stage. Back-calculated hatch dates of major carps were between 31 May and 24 July. The initiation of the spawning season was delayed about 1 month compared to pre-TGD records. Larval growth rates, as reflected by otolith-increment width, were lower at Dongting Lake (closer to TGD) than at E’zhou (farther from TGD), indicating that TGD-moderated effects on early growth and development of carps are more apparent for fishes hatched nearer to the dam. The delay in spawning and decreased early growth may partly explain the recent decline of the major carp resources in the middle and lower Yangtze River.