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首页> 外文学位 >Migration and spawning of anadromous shads in the Roanoke River, North Carolina.
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Migration and spawning of anadromous shads in the Roanoke River, North Carolina.

机译：北卡罗来纳州罗阿诺克河中适生树荫的迁移和产卵。

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摘要

Anadromous alosines are ecologically, commercially, and recreationally valuable fishes. Some populations of alosines are at historically low levels, as a result of overfishing, pollution and habitat change, including the presence of dams, which block access to historic spawning sites upstream and alter spawning habitat downstream. To aid in the restoration of alosine stocks, I evaluated several methods for spawning habitat identification and characterization and evaluated trap and transport as a method to give American shad Alosa sapidissima access to additional spawning habitat above dams in the Roanoke River, North Carolina and Virginia. The Roanoke River has four anadromous alosines: American shad, hickory shad A. mediocris, blueback herring A. aestivalis, and alewife A. pseudoharengus. For all four alosines, spawning sites river-wide were most efficiently identified using plankton tows, which collect eggs of all species. Spawning habitat selection for hickory shad and river herring (blueback herring and alewife) could be evaluated using spawning pads, which collected their eggs in clumped distributions. American shad eggs were not successfully sampled by spawning pads and spawning habitats could be best examined by visual observations of spawning splashes. Unlike the other alosines in this study, little is known about spawning habitat for hickory shad. Hickory shad eggs were collected at water temperatures from 10 to 23°C, and peaked from 11 to 14°C. Spawning generally occurred in water velocities ≥ 0.1 m/sec, over substrates free from silt. A habitat suitability model for hickory shad was developed using a Bayesian belief network. Bayesian belief networks are a relatively new method for modeling habitat suitability for fishes, but could prove very useful in the future, especially for species such as American shad which have been the focus of more study and are in need of restoration. I evaluated movement patterns and spawning of sonic-tagged adult American shad transported to habitats above dams on the Roanoke River. Most transported fish spent relatively little time in the riverine habitat considered suitable for spawning, and no eggs were collected by plankton sampling. American shad appeared to move more effectively through a smaller, as compared to a larger, reservoir, but fish released directly into riverine habitat spent the longest amount of time in suitable spawning habitat. Although the mortality associated with moving downstream through a dam turbine was generally low, few adults completed the passage, and many were observed just upstream from a dam late in the season, suggesting that structures to increase downstream passage may be beneficial. I used data on behavior and outmigration of American shad adults and fry released above and below dams on the Roanoke River to develop a deterministic, density-dependent, stage-based matrix model to predict possible population-level effects of transporting American shad to upper basin habitats. The American shad population in the Roanoke River appears small compared to assumed values of carrying capacity in the lower river and would appear to benefit from transport only under optimal conditions of young survival and effective fecundity. The matrix model predicted that under present conditions, improvements to survival rates of young or adults would likely lead to greater improvements in the stock size of American shad in the Roanoke River.
机译：脱附的芦荟碱是具有生态，商业和娱乐价值的鱼类。由于过度捕捞，污染和栖息地变化（包括水坝的存在），一些芦荟种群的数量处于历史低位，这阻碍了上游上游产卵场的进入并改变了下游产卵栖息地。为了帮助恢复芦荟种群，我评估了几种产卵栖息地识别和表征方法，并评估了诱捕和运输方法，使美洲American鱼Alosa sapidissima可以进入罗阿诺克河，北卡罗来纳州和弗吉尼亚州大坝上方的其他产卵栖息地。罗阿诺克河（Roanoke River）具有四个异常的芦荟碱：美洲sha，山核桃sha，普通青葱，蓝鲱鲱A.estivalis和阿拉维夫A. pseudoharengus。对于所有四个芦荟，使用浮游生物丝束可以最有效地识别出河床产卵地点，该丝束可以收集所有种类的卵。可以使用产卵垫评估山核桃和河鲱（蓝鲱鱼和alewife）的产卵栖息地，这些卵以成簇的形式收集卵。美国产的d鱼卵不能通过产卵垫成功采样，产卵栖息地最好通过肉眼观察产卵飞溅来进行检查。不同于本研究中的其他芦荟碱，人们对山核桃树皮产卵的环境知之甚少。在10至23°C的水温下收集山核桃树皮卵，并在11至14°C达到峰值。产卵通常发生在水流≥0.1 m / sec时，在没有淤泥的基质上。使用贝叶斯信念网络开发了山核桃树荫的栖息地适宜性模型。贝叶斯信念网络是一种用于建模鱼类栖息地适应性的相对较新的方法，但在将来可能会非常有用，尤其是对于美国American鱼等物种而言，这些物种已成为更多研究的重点并且需要恢复。我评估了运输到罗阿诺克河大坝上方栖息地的带有声音标签的成年美国American鱼的运动方式和产卵情况。大多数被运输的鱼类在被认为适合产卵的河流栖息地上花费的时间相对较短，浮游生物采样未收集到任何卵。与较大的水库相比，美洲sha鱼似乎更有效地通过较小的水库移动，但是直接释放到河流栖息地的鱼在合适的产卵栖息地中花费的时间最长。尽管与通过水坝涡轮机向下游移动相关的死亡率通常较低，但很少有成年人完成该通道，并且在本季节末期在水坝上游观察到许多成年人，这表明增加下游通道的结构可能是有益的。我使用了罗阿诺克河大坝上方和下方释放的美洲sha鱼成虫和鱼苗的行为和迁徙数据，建立了确定性，依赖密度的，基于阶段的矩阵模型，以预测将美洲d鱼运往上流域的可能的人口水平影响栖息地。与假定的下游河流承载力值相比，罗阿诺克河中的美国sha鱼种群显得较小，并且仅在年轻生存和有效繁殖力的最佳条件下才能从运输中受益。矩阵模型预测，在当前条件下，提高年轻人或成年人的生存率可能会导致罗阿诺克河中美洲American鱼种群的更大改善。

著录项

  • 作者

    Harris, Julianne Elaine.;

  • 作者单位

    North Carolina State University.;

  • 授予单位 North Carolina State University.;
  • 学科 Agriculture Fisheries and Aquaculture.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 233 p.
  • 总页数 233
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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