The Difference Between Recirculating Aquaculture Systems (RAS) and Net Pen

The difference between recirculating aquaculture systems (RAS) and net pen aquaculture operations is that ___________.

A) unlike net pen aquaculture, RAS operations are very limited to the type of fish they can culture, as most fish, especially the commercially profitable species, do not do well in enclosed facilities
B) RAS facilities are more habitat friendly compared with net pen farms, which displace mangrove swamps and other wetland ecosystems in coastal areas
C) in contrast to net pen aquaculture, RAS operations are low tech and easy to set up
D) since RAS operations are very labor intensive, they are better suited than net pen systems for developing countries, where labor is cheap and the market for farm-raised fish is large
E) net pen aquaculture, being biosecure, poses a much lower risk regarding the escape of non-native species than does an RAS operation