Addition of feed in pulses increased water particle concentration by 3-30 times, but the short duration of a pulse and saturation of mussel feeding would make long term seston concentration more important for mussel growth. The potential particle retention from a rich pulse was limited by mussel pseudofaeces threshold level. It is concluded that, in a co-cultivation of mussels and salmons, the ambient seston concentration is of greater importance in controlling mussel growth, and increases in suspended solids from the fish cages may contribute significantly only during periods of low plankton production. Oncorhynchus kisutch, O. mykiss and Gracilaria chilensis cultivation in intensive tank systems is feasible. The environmental benefits associated with the development of integrated tank cultivation were established by analyzing previously published and unpublished data on fish production and food conversion efficiency, particle discharges in fish effluents, as well as biomass production, nutrient uptake efficiency data of Gracilaria, with special emphasis on ammonium.
Fish farms produce large amounts of wastes, including dissolved inorganic phosphorus and nitrogen.
To exploit these nutrients as a resource input, and at the same time reduce the risk for eutrophication of the environment, Gracilaria chilensis on ropes was co-cultivated with a salmon cage farm in southern Chile during two summer month. The degree of epiphytes and bryozoa coverage was overall low. We conclude that both economical and environmental advantages can be achieved by integrating the cultivation of algae with fish farming in open sea systems. However, further studies focusing on full scale cultivation and functions during different seasons are needed. Fish farms produce large amounts of wastes, including dissolved inorganic phosphorus and nitrogen.