In recent years, several closed containment cages at sea have been constructed for both post-smolt and market-size fish. Studies show that these cage types yield promising biological and environmental results, and that salmon can be reared without reproduction of sea lice and other parasites.
The production cost in a closed cage will likely be higher than in open cages as a consequence of larger initial investments and the need for oxygenation and water pumping. Increased stocking density has therefore been highlighted as an important factor that can help reduce total production costs, provided this does not compromise fish welfare and performance.
In addition to higher stocking densities, there is also a trend toward larger production units. To ensure adequate water exchange in larger units with high stocking densities, new flow patterns and effects on fish behaviour and welfare must be expected. Current studies and recommendations have been conducted in much smaller units, and new investigations of hydrodynamics in units of relevant size and design are therefore necessary to establish appropriate recommendations. Numerical models will be useful for the development and improvement of large closed cages.
The project's objectives are:
- Map the interaction between hydrodynamics, stocking density and the biomass in large closed cages
- Document fish behaviour inside large closed cages with different configurations
- Develop and perform 3D flow simulations (CFD) together with an individual-based fish model and validate them with performed measurements
- Simulate flow conditions and fish behaviour for several different concepts
- Contribute to increased knowledge and understanding of dynamic responses at various salinities of flexible closed cages