Norwegian Institute for Nature Research, Tungasletta 2, N-7485 Trondheim, Norway.
J Fish Biol. 2010 May;76(7):1751-69. doi: 10.1111/j.1095-8649.2010.02614.x.
The study explored the combined effects of density, physical habitat and different discharge levels on the growth of juvenile Atlantic salmon Salmo salar in artificial streams, by manipulating flow during both summer and winter conditions. Growth was high during all four summer trials and increased linearly with discharge and mean velocity. Differences in fish densities (fish m(-3)) due to differences in stream volume explained a similar proportion of the variation in mean growth among discharge treatments. Within streams, the fish aggregated in areas of larger sediment size, where shelters were probably abundant, while growth decreased with increasing densities. Fish appeared to favour the availability of shelter over maximization of growth. Mean growth was negative during all winter trials and did not vary among discharge treatments. These results suggest that increased fish densities are a major cause of reduced summer growth at low discharge, and that habitat-mediated density differences explain the majority of the growth variation across habitat conditions both during summer and winter.
本研究通过在夏季和冬季条件下对水流进行调控，探究了密度、物理生境以及不同流量水平对人工溪流中幼年大西洋鲑（Salmo salar）生长的综合影响。在所有四个夏季试验中，鲑鱼的生长速度都很高，并且与流量和平均流速呈线性增长。由于溪流体积的不同而导致的鱼类密度（每立方米鱼数）差异，解释了流量处理之间平均生长差异的相似比例。在溪流内，鱼类聚集在较大的泥沙粒径区域，那里可能有大量的遮蔽物，而生长则随着密度的增加而下降。鱼类似乎更倾向于遮蔽物的可用性，而不是生长的最大化。在所有冬季试验中，平均生长速度均为负值，并且在不同流量处理之间没有差异。这些结果表明，在低流量下，鱼类密度的增加是夏季生长速度降低的主要原因，而在夏季和冬季，生境介导的密度差异解释了大部分生境条件下生长差异的主要原因。
