WWW.WAS.ORG • WORLD AQUACULTURE • JUNE 2016 41 do not plan stocking densities from the beginning of the season and do not consider the space and water flow requirements for good trout growth. Finally, most farmers do not keep records of growth, mortality, cost, and feed consumption of cultured fish. Most trout farmers in Hermel do not gauge water flow to raceways because many do not understand the importance of the relationship between water flow and dissolved oxygen concentration, dilution of toxic elements and removal of harmful metabolites. According to many, as long as the water flows, rainbow trout in raceways are safe, regardless of flow rate. Furthermore, farmers along the Assi River do not have the tools to measure flow volume or current velocity. They rely on observation to estimate what they perceive as adequate water flow. Feeds and Feeding Practices All farmers along the Assi River currently give rainbow trout manufactured fish feed. Most farmers (89 percent) purchase feed from importers but some (11 percent) import feed directly for personal use and sale. Farmers generally refuse to purchase feed from an importer that does not also have a farm. Many farmers cannot name the manufacturer of the fish feed they purchase but know the country of origin. Most farmers purchase whatever fish feed is available at the time feed is needed. Only two farmers specified that they gave small fish a different kind of feed than large fish. Almost all farmers understood that small fish ate a different proportion of feed relative to fish body weight than large fish. Of farmers who purchase feed, 32 percent pay cash to the merchants, 40 percent made small payments whenever possible and 17 percent pay cash or get feed on credit, depending on the availability of funds. In all cases, interest was imposed on those who purchased feed on credit. In 2013, the average price of fish feed was US $1,200/t if paid in full upon purchase but US$1,400-1,500/t if bought on credit. All farmers know some of the major ingredients in the pelleted feed but do not know the proportions. Some farmers do not feed fish for days if they did not have the money to purchase feed. Most farmers feed trout to apparent satiation as instructed by feed sales representatives but do not weigh the feed given. Feeding practice is a limiting factor in the successful growth of fish. Farm managers in Hermel do not understand feeding methods. Very few farmers are aware that fingerlings need different amounts of protein than large rainbow trout. However, because the majority of farmers purchase feed at the correct size for their fish and the feed manufacturers know the required feed composition at various sizes, the rainbow trout are fed the correct feed composition and size for each development stage. This is helped by the fact that most farms along the Assi River stock fish at the same time and have similar-size fish, so traders only import the correct feed for the period. Occasionally trout farmers in Hermel replace fish feed with poultry processing waste because they cannot always afford to purchase fish feed and because the authorities do not police the river. Farmers do not know if poultry processing waste is nutritionally better or worse than manufactured fish feed. Poultry offal does not contain the necessary nutrients required for healthy growth (Riche and Brown 1995). Farmers are aware that poultry processing waste is not environmentally friendly but believe that the river cleans itself. Farmers do not care if farms downstream are affected by deteriorated water quality or if downstream inflows are clogged by uneaten chicken processing waste. In 2007, an Italian NGO distributed free feed to many farmers. Farmers then overfed fish because the feed was free. They then claimed that the feed was not good because the feed conversion ratio was very high. This suggests farmers should not be given free feed but rather have feed partially subsidized. Otherwise, they feed excessively, which ends up being a waste and polluting the river. Farmers do not seem to fully understand feeding practices. Most farmers do not know the biomass of fish per raceway and, thus, could not make important assumptions on quantities of feed that fish should be fed. Furthermore, farmers do not keep records of water quality, mortalities and fish growth, despite the essential nature of this information to determine feeding rate. Repercussions of feeding in excess of what fish are able to metabolize include increases in the cost of production, deterioration of water quality and outbreak of diseases (Dunning and Sloan 2001, Cain and Garling 1993). Disease, Health Management and Mortality ‘Knowing how to deal with disease outbreaks can mean the difference between a successful business or going broke’ (Cain and Garling 1993). Managing disease is a major problem of trout farmers in Hermel. They did not have access to expert help. Farm managers along the Assi River mainly copy each other’s practices, without trying to find out scientific explanations behind them. Nearly all (96 percent) surveyed farmers clean and sterilize raceways between crops. Potassium permanganate was the mostused sterilization chemical. Salt is used by 47 percent of farmers and 23 percent treat raceways with quicklime. In general, farmers use chemicals only if they think there is a need. The owner of a veterinary pharmacy informed us that drugs used to treat fish include Avytril (enrofloxacin), fluorquinolone and tetracycline. However, the farmers do not know the names of the medicines they use and some purchase drugs with no labels on the bottles. When NGOs provided farmers in Hermel with non-labeled drug bottles, farmers used them to treat any symptom, irrespective of the drug. Although they knew that drug treatments were ineffective, possibly harmful and a permit was needed for use, farmers hid the FIGURE 3. Yara Daou explaining the goals of the study to a local trout farmer before starting an interview with him. The Assi River is in the background. (CONTINUED ON PAGE 42)
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