Offshore aquaculture is gaining popularity due to the immense pressure on land and near-shore-based water resources and the escalating marine pollution in the near-shore areas. A variety of offshore cage designs are available with various distinct configurations and geometry to withstand harsh sea weather conditions. However, most of them are in their infancy and are limited to developed countries that have sophisticated infrastructures to support the development, deployment, and operations of cage designs as well as sustainable aquaculture systems such as Integrated Multi trophic Aquaculture (IMTA) system. Therefore, a novel stratified fish cage design that can allow maximum uptake of nutrients in an IMTA setup was developed in this study. The design integrates distinct configurations that would allow offsetting of the drag forces experienced due to the high ocean current and wave forces. The viability of this cage was demonstrated through experiments conducted in a wave tank. The predicted numerical model of the designed cage was validated by comparing it with the experimental model and previous research studies that employed polarcirkel cages of the Akva group. The mean relative error between the experimental and the predicted numerical forces was about 15.3%, which is within the safety of factor and design considerations as per the Det Norske Veritas and Germanischer Lloyd (DNV-GL) guidelines.
Moreover, this research study aimed to address the possibility of a stratified cage design for maximum uptake of nutrients in an open sea. To address the issue of the structural response of the cage to the sea environmental loadings, tensions on the mooring were examined under varying current and wave conditions, providing information on the expected mooring forces for a stratified cage with amalgamated design configurations. The results of this study provide data on the expected anchor loads for the design of a stratified aquaculture cage in an offshore environment, precisely the maximum expected load-bearing capacity of any anchor.