RAPID: Systematic Quantification of River-bed Gravel Characteristics that Promote Salmon Spawning

在美国西部的许多河流中，太平洋鲑鱼的数量急剧减少。扭转这种下降趋势是当务之急，许多河流恢复项目每年都要花费数百万美元。为了帮助恢复鲑鱼的数量，管理人员经常向河流中注入产卵大小的砾石。然而，关于河床粗化如何影响鲑鱼产卵的定量理解很少，关于鲑鱼产卵实际需要的机械基础也很少。此外，几乎没有定量依据来确定添加砾石的最合适位置。拟议的项目试图通过系统地量化粉红鲑鱼和奇努克鲑鱼（Oncorhynchus gorbuscha和O.tshawytsha）产卵砾石的颗粒大小上限来提供这样的基础。这项工作是建立在一系列关于天然砾石产卵适宜性的机械假设的基础上，它将通过对鱼类大小、redd尺寸、流速和产卵床粒度特征的新测量来定量地探索这些假设，粉红色和奇努克鲑鱼是太平洋鲑鱼中最小和最大的物种。该项目重点关注鲑鱼洄游量高且底质粗糙的河流：普吉特湾（pujget Sound）的Puyallup河系统，预计2009年秋季粉红鲑鱼将大量洄游；Trinity河（加利福尼亚沿海），预计2009年秋季奇努克鲑鱼将大量洄游。由于距离产卵高峰的时间很短，因此快速反应的现场工作将利用大马哈鱼在粗河段大量流动的巧合。预计鱼的大小与移动的最大颗粒之间，以及在redd建造成功率与不可移动颗粒覆盖率之间存在很强的关系。该项目将有助于提高砾石增加项目的效率，并改善许多河流恢复工作的长期效果。通过促进有效的河流恢复，该项目可能有助于改善一些受威胁和濒危物种太平洋鲑鱼的生存前景。该项目培养了学术研究者和生态系统恢复咨询行业成员之间的持续合作。

Populations of Pacific salmon species have declined sharply in many rivers of the western US. Reversing these declines is a top priority and multimillion- dollar-per-year expense of many river restoration projects. To help restore salmon populations, managers often inject spawning-sized gravel into rivers. However, there is little quantitative understanding of how bed coarsening affects salmon spawning, and there little mechanistic basis concerning what the salmon actually need for spawning. Furthermore, there is little quantitative basis for determining where added gravel would be most suitable. The proposed project seeks to provide such a basis by systematically quantifying the upper, particle-size limits of spawning gravel for pink and chinook salmon (Oncorhynchus gorbuscha and O.tshawytsha). The work is founded on a series of mechanistic hypotheses about the spawning suitability of natural gravels and it will explore these hypotheses quantitatively with new measurements of fish size, redd dimensions, flow velocity, and grainsize characteristics of the bed for spawning pink and chinook salmon, the smallest and largest of the Pacific salmon species. This project focuses on rivers where salmon returns are high and substrate is coarse: the Puyallup River system (Puget Sound), where pink salmon are expected to return in exceptionally high numbers in fall 2009, and the Trinity River (coastal California), where 2009 fall-run chinook salmon are expected to return in high numbers. Because the lead time to the peak of spawning is short, a rapid response field effort will capitalize on this coincidence of large runs of salmon in coarse reaches of river. Strong relationships are expected between fish size and largest particle moved and between redd building success and percent coverage of immovable particles.This project will contribute to increased efficiency of gravel augmentation projects and improve the long-term efficacy of many river restoration efforts. By promoting effective river restoration, this project may help improve the survival outlook for some of the threatened and endangered species of Pacific salmon. The project cultivates an ongoing collaboration between the academic investigator and members of the ecosystem restoration consulting industry.