Shrimp Farming and the Environment - Library

suitable for human consumption or for which there is limited demand, or from waste products from fishprocessing for human consumption (Pike 1998).Only where locally sourced “trash” fish is used for aquaculture, in areas where a poor population relieson such fish as a source of cheap high-quality nutrition (such as Vietnam), may the use of fishmeal leadto a reduction in food security or availability to poor people. Ironically, in these places, using fishmealimported from developed countries such as Scandinavian nations, Japan, and Chile rather than locallysourced fishmeal for aquaculture is the best way to maintain food security, maximize cheap foodavailability for the poor, and minimize pressure on local fish stocks in developing countries. Muchfishmeal is produced in Ecuador, Peru, and Chile because of the abundance of coastal anchoveta in thesouthern/central eastern Pacific Ocean. However, much of the high-quality fishmeal used inaquaculture comes from Northern European countries.The argument that the conversion of fish from one form into another is fundamentally wasteful is alsoopen to question. The logic of this argument implies that to eat anything other than primary productionis wasteful. Is there any fundamental difference between eating wild or farmed carnivorous fish in thisrespect? In practice, the basis of much economic activity is the conversion of low-value materials intohigher-value materials—with, ideally, a recycling of waste back into primary production.Notwithstanding these points, it is in the industry’s interest to seek cheaper alternatives from moresustainable sources. Although there is no clear consensus on how much fishmeal can be substitutedwith other protein sources from a technical or nutritional point of view, there is little doubt that it canbe reduced substantially. As the price of fishmeal and oils rises, the incentive to replace them willincrease rapidly. Ultimately, it may be fish oils that are limiting, but progress in biotechnology mayprovide solutions in this area (Tacon 1994; Wijkström & New 1989).It can also be argued that fishmeal may not become a limiting factor, at least for some time. Today, avast resource of unused marine biomass is discarded at sea, thrown away as offal, or wasted in otherways. This biomass has been estimated by the FAO to constitute some 25 to 30 million MT per year(FAO 1997). Much of this waste could be converted into fishmeal, if it were technically andeconomically feasible. Also, alternatives to fishmeal as a protein source should be researched forshrimp diets, such as single-cell proteins. In China, fishmeal used in the feed formulated for freshwaterfish has been greatly reduced, much of it replaced with yeast. There is great scope for research in all ofthese areas.Conclusions and recommendationsLike most human activity, shrimp farming has created many different environmental impacts. Theseverity and significance of these impacts is extremely variable both within and between countries,depending on factors as diverse as hydrology, management practices, and the nature of the localeconomy. In general, these impacts are similar to those caused by agriculture; they are mainly relatedto habitat conversion (more serious with extensive shrimp farming); increased nutrient loads added tothe environment (usually more severe in the case of intensive farming); and use of chemicals to combatdisease (generally used more in intensive systems). Particular attention has been drawn to theenvironmental impacts of aquaculture because its financial attractiveness has encouraged extremelyrapid, and in most cases unplanned and unregulated, development; and because it has been developed(and was originally widely promoted) in mangrove and estuarine systems, which are already undersevere development pressure.The environmental impacts of shrimp culture can be greatly reduced through a range of practicalmeasures, as discussed in this chapter. Some of these are relatively simple to implement, while othersare much more difficult. It is likely that rather few will be adopted without significant governmentintervention and/or market incentives, discussed further in Chapter 7.The various measures for reducing environmental impacts may be classified as follows:• Site selection;• Scale and extent;• Design;• Technology and research;35