Aquaculture Proposal

The present generation of inhabitants in the coastal communes of Demak district have specialised in aquaculture, some people still practice traditional fisheries and most lost skills in cropping rice. Therefore aquaculture offers the best option for short term improvements in livelihoods. Several species that are already cultured in Demak - tiger shrimp, white legged shrimp, milkfish and tilapia – in particular offer opportunities to enhance productivity and income. This is because their market price is high, they are not sensitive to pollution/salinity and/or they are suitable for cultivation in extensive poly-culture systems. The latter is important because this allows implementation of so-called multi-trophic aquaculture systems in which

To decrease disease risk we propose a semi-intensive system with an ecological management regime, using a filter pond to prepare clean water for the shrimp ponds 32, see Figure 4.6. The aquatic organisms harvested from this so-called green-water pond moreover contribute to farm households’ nutritional food security 33. If the pond area owned by the farmer is too small, the tilapia can be raised in nets inside his/her pond. Productivity of the various aquaculture systems can moreover be improved by regularly cleaning the pond bottoms (curing), improving infrastructure for pond drainage (system of sluices and pumps), and applying aeration and by training the farmers in Coastal Field Schools. As mentioned in Chapter 2, shrimp yield and the annual profit per hectare can almost double when the farmers participate in a Coastal Field School. The yield of tiger shrimp can reach 400 kg/ha without using aerators, and easily become ten-fold (4000 kg/ha) when aerators are used. Though the yield of white legged shrimp can be ten-fold of the last, cost and risk increase

Further, to reduce disease impact when farmers want to intensify, the white legged shrimp and tiger shrimp are best cultured in so-called green-water shrimp systems using tilapia to filter the water (and perhaps also sea bass in another pond). The implementation of this more sustainable green-water shrimp system requires investment in separate in and outlet canals with sluice gates for all ponds. In the short term, the mixed mangrove-aquaculture system can be introduced along rivers to further reduce the spread of disease agents and purify water. In the longer term this system can also be introduced behind the restored coastal