Flow Fields Inside Stocked Fish Cages and the Near Environment
Flow Fields Inside Stocked Fish Cages and the Near Environment
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DOI：
10.1115/1.4027746
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发表时间：
2014-08-01
影响因子：
1.6
通讯作者：
McClimans, Thomas A.
中科院分区：
文献类型：
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作者：
Gansel, Lars C.;Rackebrandt, Siri;McClimans, Thomas A.
本研究探讨了大西洋鲑鱼 (Salmo salar L.) 鱼笼内部和周围的平均流场。进行实验室测试和现场测量，以研究鱼笼周围和穿过鱼笼的水流模式以及鱼对水流的影响。在峡湾中测量空鱼笼和放养鱼笼周围的水流，以验证没有鱼的实验室测试获得的结果，并研究鱼在笼中游泳的影响。荧光素是一种无毒的荧光染料，被释放到放养的鱼笼内，以可视化笼内的三维流动模式。大西洋鲑鱼往往会形成一个圆环形状的鱼群，并在白天沿着圆形路径游动，跟随网。目前对空鱼笼和放养鱼笼周围的测量显示，鱼以这种圆形模式游动有很大影响：虽然大部分迎面而来的水团穿过空笼，但更多的水被推到放养鱼笼周围。染料实验表明，放养鱼网箱内的地表水向中心汇聚，在中心处下沉并在最大生物量深度处扩散到网箱外。为了实现圆周运动，鱼必须向网箱中心加速。这种向内的力必须通过将水推出笼子的向外的力来平衡，从而在鱼的旋转运动中心形成低压区域。因此，水从鱼游泳深度的上方和下方被拉动。空笼实验室测试与空鱼笼周围的现场测量非常吻合，并为进一步的实验室测试提供了良好的起点，包括笼内鱼引起的电流的影响，以记录鱼笼内部和附近的流动模式的细节。此类实验的结果可用作数值模型的基准，以模拟网栏内和周围的水流，并模拟放养养鱼场附近的氧气供应和废物扩散。
This study explores the average flow field inside and around stocked Atlantic salmon (Salmo salar L.) fish cages. Laboratory tests and field measurements were conducted to study flow patterns around and through fish cages and the effect of fish on the water flow. Currents were measured around an empty and a stocked fish cage in a fjord to verify the results obtained from laboratory tests without fish and to study the effects of fish swimming in the cage. Fluorescein, a nontoxic, fluorescent dye, was released inside a stocked fish cage for visualization of three-dimensional flow patterns inside the cage. Atlantic salmon tend to form a torus shaped school and swim in a circular path, following the net during the daytime. Current measurements around an empty and a stocked fish cage show a strong influence of fish swimming in this circular pattern: while most of the oncoming water mass passes through the empty cage, significantly more water is pushed around the stocked fish cage. Dye experiments show that surface water inside stocked fish cages converges toward the center, where it sinks and spreads out of the cage at the depth of maximum biomass. In order to achieve a circular motion, fish must accelerate toward the center of the cage. This inward-directed force must be balanced by an outward force that pushes the water out of the cage, resulting in a low pressure area in the center of the rotational motion of the fish. Thus, water is pulled from above and below the fish swimming depth. Laboratory tests with empty cages agree well with field measurements around empty fish cages, and give a good starting point for further laboratory tests including the effect of fish-induced currents inside the cage to document the details of the flow patterns inside and adjacent to stocked fish cages. The results of such experiments can be used as benchmarks for numerical models to simulate the water flow in and around net pens, and model the oxygen supply and the spreading of wastes in the near wake of stocked fish farms.