Using drift nets to capture early life stages and monitor spawning of the Yangtze River Chinese sturgeon (Acipenser sinensis)
Using drift nets to capture early life stages and monitor spawning of the Yangtze River Chinese sturgeon (Acipenser sinensis)
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DOI：
10.1111/j.1439-0426.2009.01269.x
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发表时间：
2009-10-01
影响因子：
0.9
通讯作者：
Zhang, H.
中科院分区：
文献类型：
--
作者：
Wei, Q. W.;Kynard, B.;Zhang, H.
1996年至2004年，三峡大坝开始运营之前和之后，长江宜昌采用了D型底锚式流网捕获鲟鱼卵采样系统来捕获中华鲟（Acipenser sinensis）的早期生命阶段（ELS），并监测了长江宜昌每年的产卵成功率。捕获了 96 875 个 ELS（早期生命阶段：卵、卵黄囊幼虫 = 刺五加胚胎和幼虫）；大多数是卵，只有 2477 只是卵黄囊幼虫。大多数ELS是在宜昌产卵河段的主河道和河湾内捕获的。卵黄囊幼虫在孵化开始后最长 3 天的时间内被捕获，表明其向下游快速扩散。反算8年来的卵受精日表明最大产卵窗口为23天（10月20日至11月10日）。各年份的产卵都有时间限制，多发生在夜间，在一到两个产卵期，每个产卵期持续数天。短暂的产卵窗口可能会通过数以百万计的卵淹没河底来减少机会主义捕食者对卵的捕食。 1996年至2002年期间，每年20个鸡蛋样本中受精卵的百分比在63.5%至94.1%之间；然而，2003年施肥率仅为23.8%。这种突然下降可能与三峡大坝运行导致宜昌环境条件的改变有关。需要进一步的研究来监测这个受威胁种群的产卵和卵受精的变化。
P>A sampling system for capturing sturgeon eggs using a D-shaped bottom anchored drift net was used to capture early life stages (ELS) of Chinese sturgeon, Acipenser sinensis, and monitor annual spawning success at Yichang on the Yangtze River, 1996-2004, before and just after the Three Gorges Dam began operation. Captured were 96 875 ELS (early life stages: eggs, yolk-sac larvae = eleuthero embryos, and larvae); most were eggs and only 2477 were yolk-sac larvae. Most ELS were captured in the main river channel and inside the bend at the Yichang spawning reach. Yolk-sac larvae were captured for a maximum of 3 days after hatching began, indicating quick dispersal downstream. The back-calculated day of egg fertilization over the eight years indicated a maximum spawning window of 23 days (20 October-10 November). Spawning in all years was restricted temporally, occurred mostly at night and during one or two spawning periods, each lasting several days. The brief temporal spawning window may reduce egg predation by opportunistic predators by flooding the river bottom with millions of eggs. During 1996-2002, the percentage of fertilized eggs in an annual 20-egg sample was between 63.5 to 94.1%; however, in 2003 the percentage fertilized was only 23.8%. This sudden decline may be related to the altered environmental conditions at Yichang caused by operation of the Three Gorges Dam. Further studies are needed to monitor spawning and changes in egg fertilization in this threatened population.