Shrimp Farming and the Environment - Library

In practice, this analysis may be misleading, especially about the relationship between abandonmentand intensity. If badly planned and sited with inadequate or poor water supply, extensive ponds may beabandoned rather quickly, as has happened in parts of Vietnam. On the other hand, some well-managedintensive ponds have been in operation for many years and are likely to continue for many more.Critical factors are soil and water quality, and the balance between husbandry, management skills, andthe level of intensity. Markets also play a role and may interact with other factors. For example,production is likely to cease if disease is widespread and prices are relatively low.Many areas chosen for shrimp farms are simply not well suited for this activity. A classic example ofimproper groundwork in site selection occurred in Malaysia in the early 1980s, when a largecommercial investor (one of the old plantation companies) selected a site for shrimp farming withoutundertaking a proper examination of soil and water quality. The venture was a failure, and thecorporation left the shrimp farming business altogether.Mitigation and restorationIn practice, most shrimp farm sites are chosen on the basis of availability rather than suitability, andgovernment intervention in the form of land use policy and planning may therefore be required toaddress this issue. Similarly, matching skills with local circumstances and production intensity willrequire government support in the form of training and information dissemination. The dangers ofallowing this function to be undertaken by the private sector (input suppliers) have already been noted.If ponds are nonetheless abandoned, the question arises of whether to restore to natural habitat orconvert to alternative productive use. Rehabilitation of mangrove areas that have been cleared forshrimp farming has been undertaken in some areas. This process is neither difficult nor costly(Mackintosh 1996) so long as an appropriate tidal/hydraulic regime can be re-created. However, thatstep is not always easy, especially if development activities have occurred, including canal and roadconstruction and other infrastructure activities. At a minimum, however, effective breaching of dikes isrequired (Stevenson 1997; Stevenson, Lewis, & Burbridge, in press). Where natural mangrove issparse, there may also be a shortage of mangrove propagules, in which case nursery production willincrease overall costs.Conversion of such areas to alternative productive use is more difficult, since mangrove soils arecommonly unsuitable for agricultural purposes.Where ponds have been developed on land previously used for rice, rubber, coconut, or similar crops,restoration may be more difficult, depending on the extent to which the hydraulic regime has beendisrupted and soils salinized.The use of fishmeal in shrimp feedsCompound shrimp and finfish feed typically contain a significant proportion of fishmeal and fish oil,which contribute to a high nutrition diet. There is a concern that aquaculture will put significantdemands on the supply of fishmeal in the future (Tacon 1996) and that this will increase pressure oncapture fishery resources, leading to depletion. Furthermore, it has been argued that the conversion ofone form of fish into another is necessarily inefficient and wasteful. Shrimp farming is therefore badfor the environment and questionable for food security (Naylor et al. 1998).There is little doubt that dependence on fishmeal poses a long-term financial risk to shrimp farmingand the culture of other species (including intensive livestock production of all kinds) that require highqualityprotein feeds. It is also the case that many fisheries, including some of those for “trash” fish, arenot being managed sustainably, and that a truly environmentally responsible industry will seek tominimize its use of inputs from unsustainable sources.However, the issue is extremely complex. The argument that aquaculture will be responsible for thedemise of these fisheries, or that aquaculture actually decreases food security, is questionable.Aquaculture represents only one of many sources of demand for industrial fish and fish products, andwhatever course aquaculture takes in the future, it is likely that the demand for fishmeal and fish oilswill remain strong. In any case, fishmeal and fish oil are produced mainly from species that are not34