Large-Scale Offshore Fish Farms:
The population growth and dietary preference lead to a growing demand for seafood; thus, aquaculture in seawater has become an efficient farming technique. Most aquaculture industry using open cages and flexible floating collars are typically limited to sheltered coastal locations.
Due to the lack of suitable sheltered locations, parasite infections, oxygen deficits and waste pollution in coastal areas, the development of novel fish farming concepts in more exposed locations is imperative. This development has recently been accelerated by the announcement of development licenses in Norway that can be awarded for full scale testing of new concepts to overcome the current challenges faced by the fish farming industry.
Experiences from the offshore oil and gas industry over the past decades provide solid foundations to design new offshore fish cages. In addition to designing a robust structure to withstand the harsh environment, the welfare of fishes need to be ensured by implementing new design considerations.
Moreover, the structure-net-fish interactions need to be taken into account when evaluating the behavior of the fish farm. To overcome the aforementioned challenges and to improve the design of offshore fish farms, accurate dynamic response and structural analysis are essential.
In addition, the water particle velocities acting on the downstream net elements are reduced compared to the incoming flow velocities due to the wake influences from the upstream net elements. This velocity reduction effect increases significantly with biofouling on the nets.
The research work at UiS focuses on the development of fish farm structures for exposed offshore locations. Detailed numerical studies including global response and hydrodynamic analysis, local structural and fatigue analysis are performed on the coupled system, including the support structure, the net cage and the mooring system.
Advanced numerical models based on computational fluid dynamics (CFD) is developed to solve the fluid structure interactions more accurately. Furthermore, scaled model tests of the proposed fish farm structure will be performed in the towing tank at Harbin Engineering University, China to validate the numerical models.
The feasibility of the proposed design will be studied in the model scale via experiments and in the full scale with the validated numerical models. The numerical and experimental study will also provide recommendations for the development of design standards for open sea fish farms. Currently,
UiS researchers also provide technical assistance to Norwegian aquaculture companies in development license applications.
Contaminant and Sea Lice Transport:
One of the key needs of the aquaculture and fisheries sectors is the implementation of effective analyses and management methods to ensure the sustainability, economic viability, minimization of negative impacts on the environment, and risks to human health.
Food waste and sea lice infection are two important issues we need to consider when large-scale fish farming is being promoted. It is vital to perform ocean modelling to obtain the flow condition at the targeted farming site in order to ensure that there will not be high concentrated pollution of food waste and sea lice infections.
Numerical simulations of ocean modelling with contaminant transport (food waste and sea lice infections taken as the contaminant sources) will be performed. This study will provide useful engineering assessment regarding the potential of pollution threat to the fish farm owner and designers before they decide the location of farming site.