RAS CONCEPT

The aquaculture industry that began developing in the late
1960s has exploded into a major global industry of 60 million tons
a year, with huge annual revenues in excess of US$ 70 billion (FAO,
2006). With the current increase in environmental awareness and
the consequent stringency in environmental legislation, a new
approach to dealing with the ecological problems associated with
aquaculture has been developed—recirculating aquaculture systems
. This approach was originally developed to provide a solution
to the environmental problems generated by the traditional pond
and flow-through aquaculture systems, since it enables the
treatment of polluted water within a closed loop, offers improved
control of effluent discharge, and allows complete environmental
control (van Gorder, 1994; Shnel et al., 2002). Moreover, RAS
confers ecological and economic advantages in that it facilitates a
reduction in the amounts of water and energy required and
reduces land use. In addition, it provides growers with the
geographical freedom to set up aquaculture systems in ‘‘nontraditional’’
farming areas (Shnel et al., 2002); for example, small RAS,
such as the one presented in this study, producing lucrative
seafood species might be suitable for small-scale aquaculture for
food production in urban areas (Zohar et al., 2005). Thus, RAS could
contribute to meeting the demand for protein foods in highly
populated urban centers.