Mapping the potential for offshore aquaculture of salmonids in the Yellow Sea

Mariculture has been one of the fastest-growing global food production sectors over the past three decades.With the congestion of space and deterioration of the environment in coastal regions,offshore aquaculture has gained increasing attention.Atlantic salmon(Salmo salar)and rainbow trout(Oncorhynchus mykiss)are two important aquaculture species and contribute to 6.1%of world aquaculture production of finfish.In the present study,we established species distribution models(SDMs)to identify the potential areas for offshore aquaculture of these two cold-water fish species considering the mesoscale spatio-temporal thermal heterogeneity of the Yellow Sea.The values of the area under the curve(AUC)and the true skill statistic(TSS)showed good model performance.The suitability index(SI),which was used in this study to quantitatively assess potential offshore aquaculture sites,was highly dynamic at the surface water layer.However,high SI values occurred throughout the year at deeper water layers.The potential aquaculture areas for S.salar and O.mykiss in the Yellow Sea were estimated as 52,270±3275(95%confidence interval,CI)and 146,831±15,023 km^(2),respectively.Our results highlighted the use of SDMs in identifying potential aquaculture areas based on environmental variables.Considering the thermal heterogeneity of the environment,this study suggested that offshore aquaculture for Atlantic salmon and rainbow trout was feasible in the Yellow Sea by adopting new technologies(e.g.,sinking cages into deep water)to avoid damage from high temperatures in summer.

Dynamic Analysis for the Global Performance of An SPM-Feeder-Cage System Under Waves and Currents

In the present study, the dynamic response of a coupled SPM-feeder-cage system under irregular waves and shear currents is analyzed. A numerical model is developed by using the commercial software Orca Flex. Hydrodynamics coefficients of the vessel are calculated by using a 3D diffraction/radiation panel program. First- and second-order wave forces are included in the calculations. Morison equation is used to compute the drag force on line elements representing the net. Drag coefficients are determined at every time step in the simulation considering the relative normal velocity between the structural elements and the fluid flow. The dynamic response of the coupled system is analyzed for various environments and net materials. The results of the study show the effects of solidity ratio of the net and vertical positions of the cage on the overall dynamic response of the system, confirming the viability of this type of configuration for future development of offshore aquaculture in deep waters.