Recirculating aquaculture systems (RAS)

what’s RAS …?

A recirculating aquaculture system is an enclosed system where the only water replacement is the water lost to evaporation and cleaning. These systems are being deployed in developed countries such as the Australia where coastal land costs and labor costs are very high. There are several advantages in using recirculating aquaculture systems over traditional fish farming systems:

During  the past years  the  trend has also been  to move  from conventional open systems  to
high  density  and  highly  productive  land-based  recirculation  systems,  at  least  at
experimental  and pilot  scale  and  in  growing number of  cases  at  commercial  scale. These
systems  can  be  considered  as  artificial  ecosystems  with  alternative  production  schemes
compared  to  conventional  systems,  providing  optimal  natural  conditions  for  organisms
while being uncoupled  from natural ecosystems. This  trend has been  triggered by  several
simultaneously  acting  factors  which  are  coupled  with  the  need  for  specialization,  for
example: (a) holding brood stocks under controlled conditions  to secure  timed maturation,
(b)  master  larval  development  and  growth,  and  (c)  promote  fingerling  or  juvenile
production at fixed rates.

Recirculating  systems  have  been  investigated  by  many  authors.  Before  the  turn  of  the
century  the work was mainly  descriptive  and  analytical. With  the  beginning  of  the  new
millennium  numerous  studies  looked  at  overall  system  performance  and  on  specific
dynamics of individual processes and components.
During  the  past  ten  years  research  on  recirculation  systems  and  its  application  in
aquaculture has been extensive, with many studies considering technical aspects of system
component design and their performance. However, there is no single recommended design
for a recirculating aquaculture system.