Van Leeuwen C H A, Dokk T, Haugen T O, Kiffney P M, Museth J
Norwegian Institute for Nature Research (NINA), Fakkelgården, 2624, Lillehammer, Norway.
Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, P. O. Box 1066 Blindern, 0316, Oslo, Norway.
J Fish Biol. 2017 Jun;90(6):2412-2424. doi: 10.1111/jfb.13326. Epub 2017 May 7.
Behaviour of early life stages of the salmonid European grayling Thymallus thymallus was investigated by assessing the timing of larval downstream movement from spawning areas, the depth at which larvae moved and the distribution of juvenile fish during summer in two large connected river systems in Norway. Trapping of larvae moving downstream and electrofishing surveys revealed that T. thymallus larvae emerging from the spawning gravel moved downstream predominantly during the night, despite light levels sufficient for orientation in the high-latitude study area. Larvae moved in the water mostly at the bottom layer close to the substratum, while drifting debris was caught in all layers of the water column. Few young-of-the-year still resided close to the spawning areas in autumn, suggesting large-scale movement (several km). Together, these observations show that there may be a deliberate, active component to downstream movement of T. thymallus during early life stages. This research signifies the importance of longitudinal connectivity for T. thymallus in Nordic large river systems. Human alterations of flow regimes and the construction of reservoirs for hydropower may not only affect the movement of adult fish, but may already interfere with active movement behaviour of fish during early life stages.
通过评估挪威两个大型相连河流系统中鲑科欧洲茴鱼幼体从产卵区向下游移动的时间、幼体移动的深度以及夏季幼鱼的分布情况，对欧洲茴鱼幼鱼期的行为进行了研究。对向下游移动的幼体进行诱捕和电鱼调查发现，尽管在高纬度研究区域光线水平足以用于定向，但从产卵砾石中孵出的欧洲茴鱼幼体主要在夜间向下游移动。幼体大多在靠近底层的水层中移动，而漂流物则在水柱的所有水层中被捕获。秋季时，很少有当年幼鱼仍栖息在产卵区附近，这表明它们进行了大规模移动（数公里）。综合这些观察结果表明，欧洲茴鱼幼鱼期向下游移动可能存在有意的、主动的成分。这项研究表明了纵向连通性对北欧大型河流系统中欧洲茴鱼的重要性。人类对水流状态的改变以及水电水库的建设不仅可能影响成年鱼的移动，还可能已经干扰了鱼类幼鱼期的主动移动行为。
