Numerical study of the mooring system failure of aquaculture net cages under irregular waves and current

Potential for Coastal and Offshore Aquaculture in Portugal: Insights from Physico-Chemical and Oceanographic Conditions

“…All studied areas had significant wave heights that exceeded 6 m. According to [119], until further technological solutions allow offshore aquaculture to be developed, the coastal modality is a more pragmatic option for the North Region (Area A) in Portugal. Area E comes close to the wave height studied by [148] with a significant height of 6.97 m. In this area, if the anchor system does not fail, the aquaculture production system should endure storm conditions, and if the aquaculture cage can be successfully placed, other variables need to be added for the biological necessities of the selected species. For example, [59] mention that the Atlantic salmon behaves differently in no light conditions, which results in sub-optimal higher densities (in high-density stocks) but the placement of artificial lights in 15 m depth cages resulted in a lower density.…”

“…The net cages have innumerable factors that require deep analysis to ensure the safety of production. These factors range from the cage structure itself and deployment depth; the location and weight of the anchors; the ropes attached to the cage; the drag forces applied on the structure by currents and waves; backup plans if the anchors get dragged on the sea floor; ropes entanglement; uncommon sea conditions that may damage the materials, such as storms [146][147][148]. Light intensity, the availability of dissolved oxygen, rearing density and food supply capacity should also be considered for the survival and welfare of the species produced in submerged cages [59,149,150].…”

“…Light intensity, the availability of dissolved oxygen, rearing density and food supply capacity should also be considered for the survival and welfare of the species produced in submerged cages [59,149,150]. Nevertheless, aquaculture cages had rapidly developed in the last decades [148] and can cope with these factors to a certain degree. For instance, the authors [146][147][148] studied the impact of currents and waves in aquacultures cages.…”

“…Nevertheless, aquaculture cages had rapidly developed in the last decades [148] and can cope with these factors to a certain degree. For instance, the authors [146][147][148] studied the impact of currents and waves in aquacultures cages. It was observed by [146] that drag forces are dependent on the cage size and system used, where sea currents from 0.2 m s −1 to 0.5 m s −1 had a proportional increase on the lift force.…”

“…Since every studied area had a current velocity that exceeded 0.3 m s −1 , using a larger mesh in these areas would reduce the drag from the waves and currents. In case of an emergency, [148] set an experiment where the mooring system failed, and the cage was subjected to waves and currents. The conditions of this experiment were quite extreme, where the significant wave height reached 6 m and the current velocity reached 2 m s −1 .…”