Training manual on “Cage Culture of Marine Fin fish and Shell fish in Open Sea” 13 Introduction Cage culture is an utilisation of existing water bodies with little or no economic costs. The selection of a suitable site for a cage farm is indispensible for their effective function, particularly in relation to proper water quality within the cage and reduced environmental impacts around the cage and for the economic viability of the cage farm. The natural tolerance of species should be studied for assessment of suitable site. Criteria for selecting a site for marine cage culture: 1. The cage site should be of suitable depth, have good tidal flow with optimal conditions and ideally be protected from strong winds and rough weather. 2. Good water exchange is essential at cage farm sites to replenish oxygen within the cages and to prevent build-up of wastes beneath the cages. Sites with a slower water exchange rate may be preferred in cases where nature is relied upon for supplemental feeding. 3. Cages should be placed at some distance from navigation routes as waves created from the wake of passing vessels may pose physical damage to cage structures. 4. Cage sites should be free from waste disposals from industries and from municipal, industrial and agricultural runoff. 5. It is necessary to allow sufficient depth under the cage in order to maximize water exchange, avoid oxygen depletion, accumulation of debris and build-up of some noxious gases generated by decomposition of the deposited wastes. 6. Site with sloping areas from the shore leading to flat bottoms are suitable for cage culture because the waste build-up at the bottom is easily eliminated. 7. Site selection criteria should also include accessibility to the cages and the ability to move them out of potential harmful events such as algal blooms and/or low DO events. 8. Sites with high fouling rate and more frequent toxic algal blooms occurrence should be avoided. 3 SITE AND SPECIES SELECTION IN SEA CAGE AQUACULTURE Ramkumar, S., P. A. Khandagale, Sujith, S. K.