Johannesen Ása, Patursson Øystein, Kristmundsson Jóhannus, Dam Signar Pæturssonur, Klebert Pascal
Department of Technology and Environment, Fiskaaling, Hvalvík, Faroe Islands.
RAO, Kirkjubøur, Faroe Islands.
PeerJ. 2020 Jun 18;8:e9313. doi: 10.7717/peerj.9313. eCollection 2020.
Disease, pest control, and environmental factors such as water quality and carrying capacity limit growth of salmon production in existing farm areas. One way to circumvent such problems is to move production into more exposed locations with greater water exchange. Farming in exposed locations is better for the environment, but may carry unforeseen costs for the fish in those farms. Currents may be too strong, and waves may be too large with a negative impact on growth and profit for farmers and on fish welfare. This study employed two major fish monitoring methods to determine the ability of Atlantic Salmon () to cope with wavy conditions in exposed farms. Echosounders were used to determine vertical distribution and horizontal preference of fish during different wave and current conditions as well as times of day. Video cameras were used to monitor shoal cohesion, swimming effort, and fish prevalence in locations of interest. The results indicate complex interacting effects of wave parameters, currents, and time of day on fish behaviour and vertical distribution. During the day, hydrodynamic conditions had stronger effects on vertical distribution than during the night. In weak currents, fish generally moved further down in taller waves, but stronger currents generally caused fish to move upwards regardless of wave conditions. Long period waves had unpredictable effects on vertical distribution with fish sometimes seeking deeper water and other times moving up to shallower water. It is unclear how much the cage bottom restricted vertical distribution and whether movement upwards in the water columns was related to cage deformation. In extreme cases, waves can reach below the bottom of a salmon cage, preventing fish from moving below the waves and cage deformation could exacerbate this situation. Farmers ought to take into consideration the many interacting effects on salmon behaviour within a cage as well as the potential for cage deformation when they design their farms for highly exposed locations. This will ensure that salmon are able to cope when storms and strong currents hit at the same time.
疾病、病虫害防治以及水质和承载能力等环境因素限制了现有养殖区域内鲑鱼产量的增长。规避此类问题的一种方法是将养殖转移到水流交换更频繁的更开阔区域。在开阔区域养殖对环境更有利，但可能给这些养殖场中的鱼类带来不可预见的成本。水流可能过强，海浪可能过大，这会对养殖户的生长和利润以及鱼类福利产生负面影响。本研究采用了两种主要的鱼类监测方法来确定大西洋鲑（）在开阔养殖场应对波浪条件的能力。回声测深仪用于确定不同波浪和水流条件以及一天中不同时段鱼类的垂直分布和水平偏好。摄像机用于监测感兴趣区域内鱼群的凝聚力、游动努力程度和鱼类数量。结果表明，波浪参数、水流和一天中的时间对鱼类行为和垂直分布具有复杂的相互作用影响。白天，水动力条件对垂直分布的影响比夜间更强。在弱水流中，鱼类通常在较高的波浪中向下移动得更远，但较强的水流通常会导致鱼类向上移动，而与波浪条件无关。长周期波浪对垂直分布具有不可预测的影响，鱼类有时会寻找更深的水域，有时会向上移动到较浅的水域。尚不清楚网箱底部对垂直分布的限制程度以及在水柱中向上移动是否与网箱变形有关。在极端情况下，海浪可以到达鲑鱼网箱底部以下，阻止鱼类移动到波浪以下，而网箱变形可能会加剧这种情况。养殖户在为高度开阔的区域设计养殖场时，应考虑网箱内对鲑鱼行为的多种相互作用影响以及网箱变形的可能性。这将确保鲑鱼在风暴和强水流同时来袭时能够应对。
