Design theory in offshore fish cage designing

Population increase, food security, employment, stresses on the fresh water resources and uncertainty associated with wild fish stocks are key parameters driving the demand for aquaculture expansion. Limitation in adequate waters in the coastal and near-shore sites for aquaculture development and the interactions within and from other coastal services forces the fish farming industry to move further offshore. Impact on the environment is an increasing concern that has to be considered in any aquaculture system designing. Moving further offshore could provide a better return on investment through various factors such as reduced mortality, better growth rates, less diseases and net fouling. However, moving offshore comes with a new set of challenges in withstanding severe weather conditions and safe and economic functioning of the aquaculture systems. Currently, the offshore fish cage design concepts are in their infancy and there is a race towards an optimum cage design for the offshore environment. Hence, in the aim of deriving an optimum cage design concept, this paper attempts to apply a holistic and theoretical approach to fish cage designing. By the application of theory of design, but different from the traditional engineering designing process, the paper proposes a conceptual framework and a cage design concept for offshore fish cage designing.

► There is an overwhelming demand for aquaculture expansion.
► Fish, fish farmer and societal groups are found to be key stakeholders.
► Economical and technological viability is taken as functional requirements.
► Optimum design is a robust offshore system allowing safe husbandry tasks.
► Design should also consider characteristics for fish welfare.