Despite the popularity of barrier removal as a habitat restoration technique, there are few studies that evaluate the biological effects of restored stream crossings. An extensive post‐treatment study design was used to quantify fish populations (e.g. species, life stage, abundance) and habitat attributes (e.g. gradient, geomorphic channel units) at 32 culvert removal or replacement projects to determine their effectiveness in restoring habitat access for juvenile salmon, Oncorhynchus spp., and steelhead, O. mykiss (Walbaum), in the Columbia River Basin, USA. Anadromous fish (steelhead, Chinook salmon O. tshawytscha [Walbaum]) abundance, juvenile steelhead abundance and habitat conditions were not significantly different between paired reaches (i.e. upstream and downstream of former barrier sites), suggesting these sites are no longer full barriers to movement. This suggests that barrier removal projects on small Columbia Basin streams provide adequate fish passage, increased habitat availability and increased juvenile anadromous fish abundance immediately upstream of former barriers.

中文翻译：

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哥伦比亚河流域溯河鲑鱼和硬头鱼去除不可逾越障碍的评价

尽管屏障清除作为栖息地恢复技术很受欢迎，但很少有研究评估恢复的河流交叉口的生物效应。一项广泛的后处理研究设计用于量化 32 个涵洞拆除或更换项目中的鱼类种群（例如物种、生命阶段、丰度）和栖息地属性（例如梯度、地貌通道单元），以确定它们在恢复幼鱼栖息地的有效性美国哥伦比亚河流域的鲑鱼 Oncorhynchus spp. 和 Steelhead O. mykiss (Walbaum)。溯河鱼类（钢头、奇努克鲑鱼 O. tshawytscha [Walbaum]）丰度、钢头幼鱼丰度和栖息地条件在配对河段（即前屏障位点的上游和下游）之间没有显着差异，表明这些站点不再是完全的移动障碍。这表明哥伦比亚盆地小溪流上的屏障清除项目提供了足够的鱼类通道，增加了栖息地的可用性，并增加了紧邻前屏障上游的幼鱼溯河鱼类丰度。