Recirculating Aquaculture Systems

Abstract

Closed-system aquaculture presents a new and expanding commercial opportunity. Recirculating aquaculture systems (RAS) are tank-based systems in which fish can be grown at high density un- der controlled environmental conditions. They are closed-loop facilities that retain and treat the water within the system. In a RAS, water flows from a fish tank through a treatment process and is then returned to the tank, hence the term recircu- lating aquaculture systems. RAS can be designed to be very environmentally sustainable, using 90-99 percent less water than other aquaculture systems. RAS can reduce the discharge of waste, the need for antibiotics or chemicals used to com- bat disease, and fish and parasite escapes. RAS have been under development for over 30 years, refining techniques and methods to increase pro- duction, profit and environmental sustainability. There is a large cost involved in setting up and running a recirculation system and we need to consider a number of factors in designing the sys- tem that will fit our needs. This type of aquacul- ture production system is more commonly used in freshwater environments and can also be used in marine environments. Since failure of any compo- nent can cause catastrophic losses within a short period of time, the system must be reliable and constantly monitored. An important component of RAS is the control system which must meas- ure and control all the critical system parameters. Recent developments in control technology and microcomputers may revolutionize the operation and control of RAS. A properly-controlled RAS will also be energy efficient since production can be optimized with respect to the various inputs. In addition, water levels, disruption of electric pow- er, fire, smoke and intrusion of vandals should also be monitored. Biosecurity