THE USE OF SEAWEEDS IN INTEGRATED AQUACULTURE: THE CHILEAN EXPERIENCE

Buschmann, A. H. Departamento de Acuicultura, Universidad de Los Lagos, Casilla 933, Osorno, Chile.abuschma@ulagos.cl In Chile, salmon cultivation is well established, and produces over 200,000 tons yr‐1. Integrated aquaculture has been proposed as an environmentally friendly way of recycling the waste of intensive aquaculture practices. An initial approach has been considered which contemplates the use of culture lines surrounding fish cages. Several studies have demonstrated under these conditions seaweeds can maintain higher production levels and present higher nitrogen contents as compared to cultures without the presence of fish cages. However, success has not been total, partly because the amount of seaweeds required to remove a significant proportion of the waste produced from intensive large‐scale cultivation systems is very large. In this context, the use of a multi‐layered seaweed cultivation of Gracilaria and Macrocystis is suggested. On the other hand, land‐based systems have been proposed as a technological alternative for integrated aquaculture. The latter type of systems are technically feasible, although, the high level of investment required at present. Our results indicate that Gracilaria is capable of removing a significant proportion of the ammonium excreted by fish. These studies indicate that annual fish production can reach over 30 kg.m‐3, with an associated Gracilaria production of 49 kg (wet). m‐2. y‐1. Finally, the environmental benefits associated with the development of integrated tank cultivation were assessed indicating that by integrating seaweed cultivation into a fish farm, the economic profitability of a commercial fish operation is not affected when internalizing the environmental costs which could be incurred for environmental compliance. (Grant: FONDEF D991/1101)