Abstract During the last century, the majority of Swedish rivers were heavily channelized to facilitate timber floating. This dramatically altered in-stream habitat by reducing the structural heterogeneity and increasing water velocity, which in turn had effects on the aquatic fauna. Today, extensive efforts to restore channelized rivers are being made by adding boulders to the streambed. In northern boreal rivers, evaluations of such restorations are often based on the response of trout and salmon populations. Few studies have investigated the effect on European grayling (Thymallus thymallus L), despite it being an important and vulnerable gamefish in both North America and Europe. This 6-year study investigated the effect of streambed restoration on grayling in a channelized, regulated (hydro-peaking) river in northern Sweden open to recreational fisheries. No effects on habitat preference, size, body condition, abundance or survival of grayling could be detected. The results are discussed based on grayling habitat preferences and behaviour, and give perspectives on streambed restoration in river conditions common to many Scandinavian grayling rivers today. The study is one of very few that presents multiyear abundance and survival estimates of grayling in a large boreal river.

中文翻译：

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添加巨石对瑞典一条沟渠中的欧洲鳟鱼 (Thymallus thymallus) 的影响

摘要 在上个世纪，瑞典的大部分河流都进行了大量渠化，以促进木材的漂浮。这通过减少结构异质性和增加水流速度，极大地改变了河内栖息地，这反过来又对水生动物产生了影响。今天，通过在河床中添加巨石，正在努力恢复渠道化河流。在北北方河流中，对此类恢复的评估通常基于鳟鱼和鲑鱼种群的反应。很少有研究调查对欧洲鳟鱼 (Thymallus thymallus L) 的影响，尽管它在北美和欧洲都是一种重要且脆弱的游戏鱼。这项为期 6 年的研究调查了河床修复对沟渠中河鳟的影响，瑞典北部受管制的（水力峰值）河流向休闲渔业开放。未检测到对栖息地偏好、大小、身体状况、丰度或茴鱼的存活率的影响。结果根据河鳟栖息地偏好和行为进行了讨论，并给出了当今许多斯堪的纳维亚河鳟常见河流条件下河床恢复的观点。该研究是为数不多的一项研究，其中介绍了一条大型北方河流中鳟鱼的多年丰度和存活率估计。