3. Potential impact of nutrient substitutes in aquafeeds on fish health and on the food safety of aquaculture products 3.1 ImPACTS OF RISING AqUAFEED COSTS AND PRICE VOLATILITy ON THE HEALTH AND PRODUCTIVITy OF FISH

3.1 ImPACTS OF RISING AqUAFEED COSTS AND PRICE VOLATILITy ON THE HEALTH AND PRODUCTIVITy OF FISH In most major aquafeed-based intensive aquaculture production systems there is a high reliance on nutritionally balanced complete aquafeeds. In situations where on-farm feeds are made, farmers attempt to produce a balanced feed using vitamin and mineral premixes. In all regions of the world, the increase in the cost of raw ingredients for commercially manufactured or on-farm aquafeeds resulted in an increase in aquafeed prices from 20 to 40 percent, thus forcing farmers to adopt alternative strategies to secure feeds. In the light of such price increases, farmers are increasingly looking for alternative sources of feeds such as trash fish, animal by-products and grain by-products, or are reverting to the use of single ingredient supplementary feeding regimes, reduced feeding frequency and ration. These types of interventions to mitigate against rising feed costs will compromise fish growth, health and welfare and could reduce fish productivity and production. As prices of raw ingredients increase, farmers have to travel farther distances to obtain cheaper and alternative feedstuffs, incurring longer transport times under suboptimal conditions of heat and humidity, and store greater than normal quantities of ingredients under suboptimal storage conditions, resulting in spoilage, and fungal and bacterial contamination. These contaminants are pathogenic to fish as well as humans. The subsequent use of such ingredients or contaminated diets could reduce growth and reduce survival. Aquafeeds can serve as a carrier for a range of microbial contaminants such as moulds, mycotoxins and bacteria (Maciorowski et al., 2007). Bacterial contamination of feed ingredients or diets with potential pathogens such as Salmonella, E. coli, Staphylococcus, Streptococcus, Pasteurella, Pseudomonas, and Clostridia will compromise fish and human health. Its impact may be relevant across the whole aquaculture sector, because the route of such contamination can be through both plant and rendered animal protein sources (Barakat, 2004; PDV, 2007).