Recirculated aquaculture systems or RAS systems are what will be used in the future of fish farming. They are already starting to show their muscle in numerous sectors for reasons of technological advancement and understanding of what actually transpires in a RAS system. Engineering is being undertaken to explain failures that have occurred in the past and more and more aquaculture developments are happening in this space.
RAS is a means of producing fish that is different from other, more simple approaches such as cage farming, or pond farming. RAS affords a controlled environment over which water quality, temperature, feeding and oxygen levels can be monitored, predicted and hence managed. What this means for you is that your production can be predictable and measurable, with changes to it being detected early for corrective action to be implemented.
RAS has a bad rap and is often cited as ‘not working’. This is not the fault of the technology, it is the fault of the implementer not adequately engineering the system, not adequately understanding all the complex interactions between factors influencing growth and failing to take these into consideration appropriately, or in some cases, just building something for the sake of building it. You can’t make this stuff up, and you have to have a comprehensive understanding of the complex relationships that exist between the many controllable parameters that you have to manage to attain an optimum environment for the optimum growth rates of your fish.
RAS affords you management, predictability, control over water parameters and frees you from reliance on ambient conditions (such as temperature of a lake) to produce your product. RAS systems can be located anywhere in other words, with the proviso that energy costs are correctly traded off in the business plan.
At Rydawi, we work with RAS systems primarily. In large project developments however, we will look at alternate means of production, such as pump ashore hybrid model development, or flow through systems.
The Aquaculture Production Unit, APU, is a low intensity RAS based system that you will probably start using as the first step in your fish farming career for the reasons that will become apparent the more you read on.