Stream Segments Captures and Crossings Associated With 2012 Aquatic Organism Passage Study Siuslaw National Forest

Stream segments, aquatic organism captures, stream surveys, and road-stream crossings described by these metadata accompany a 2012 electrofishing study of the distribution and abundance of aquatic organisms (fish, lampreys, amphibians and crayfish), conducted by the U.S. Geological Survey, and the Pacific Northwest Region Aquatic and Riparian Ecosystem Monitoring Project (AREMP) of the U.S. Forest Service, in the Siuslaw National Forest in western Oregon, USA. The purpose of the study was to quantify the effectiveness of stream-road crossing restoration (culvert replacement to the stream simulation standard) in terms of numbers of fish and length of stream gained through restoration, and to quantify the continuing effects of replaced and non-replaced crossings on the probability of passage by aquatic organisms compared to stream reaches having no road crossing. The sampling design is nested in several ways; sampled stream segments (30-m electrofishing plots) were selected in a spatially balanced random sample within stream networks (contiguous spatial collections of segments within 2 km of a study culvert or road crossing). Networks themselves were randomly sampled for study from the 79 networks in the scope of inference with probability proportional to the length of stream suitable for sampling [< 25% average gradient, < 10 km2 in drainage area, and > 0.283 l.s-1 (0.01 cubic feet per second) in mean annual discharge]. The scope of inference was defined as stream within 2 km of a study crossing (303 stream-road crossings identified as potentially important to salmon and trout based on channel slope, valley bottom morphology, and stream size). At sampled segments electrofishing was used to capture aquatic organisms for identification, counting, and at a sub-sample of sites marking for capture-recapture study. Recapture passes were conducted two days after the initial electrofishing pass.

本数据集配套的元数据涵盖溪流河段、水生生物捕获记录、溪流调查数据以及道路-河流交叉口相关信息，其关联的是2012年一项电渔法（electrofishing）研究。该研究由美国地质调查局（U.S. Geological Survey）与美国林务局太平洋西北地区水生与河岸生态系统监测项目（AREMP）共同实施，开展于美国俄勒冈州西部的锡修斯国家森林，研究主题为鱼类、七鳃鳗、两栖动物及小龙虾等水生生物的分布与丰度。
本研究的核心目标包括两方面：其一，量化道路-河流交叉口修复（按溪流模拟标准更换涵洞）的生态效益，具体评估修复后新增的鱼类种群数量与可通行溪流长度；其二，对比无道路交叉口的自然河段，量化已修复与未修复的道路-河流交叉口对水生生物通行概率的持续影响。
本次采样设计采用多层嵌套结构：采样所用的溪流河段（30米电渔法样地）通过空间均衡随机抽样的方式，在河网范围内选取；此处的河网指研究涵洞或道路-河流交叉口周边2公里范围内的连续连片河段集合。
研究河网从符合推断范围的79个河网中随机抽取，抽样概率与该河网内适合采样的溪流总长度成正比。适合采样的溪流需满足以下筛选条件：平均坡度<25%、流域面积<10 km²、年平均径流量>0.283 L·s⁻¹（即0.01立方英尺每秒）。
本研究的推断范围被定义为研究交叉口周边2公里范围内的溪流，共计识别出303个道路-河流交叉口，这些交叉口根据河道坡度、河谷地貌与溪流规模被认定为对鲑鱼与鳟鱼具有潜在生态重要性。
在选定的采样河段中，研究人员采用电渔法采集水生生物以完成物种鉴定与种群计数；同时在部分子采样点开展标记重捕（mark-recapture）研究，对采集个体进行标记。首次电渔采样完成两天后，开展重捕采样环节。