WWW.WAS.ORG • WORLD AQUACULTURE • SEPTEMBER 2017 41 farms in most parts of Ecuador. Feed is considered to be the main production cost and also one of the main factors affecting success in aquaculture. It is also the main source of pollution. It is not easy to achieve an optimum feeding level: too much results in increased feed conversion ratio, feed costs and pollution, too little and shrimp will not grow fast enough and feed conversion ratio and costs also go up. In the 1980s, feeding rates were mostly calculated using feeding and survival tables, corrected by arbitrary criteria related to optimal growth: if growth rate was high, feeding was not increased. Feed was mostly broadcast all over the pond from a canoe once daily. Most ponds in the early years were stocked with wild seed. When buying wild seed, machete (a way of undercounting shrimp seed) was a widely used method and bycatch associated with wild seed increased the real biomass in the pond. As a result, underfeeding was a common practice, leading to poor growth. It was not too rare to have ponds with more than 100 percent survival or with a large proportion of the biomass consisting of other species. In the 1990s, with mortalities related to the Seagull Syndrome, Taura Syndrome and vibriosis, survival tables became impractical. Better ways of assessing biomass in the pond and the use of other tools to determine feed consumption led to better feed management. Feeding trays became a trend after 1995 for partial (control) feeding or for feeding the whole pond. Feeding tables were quickly deemed obsolete and feeding several times a day started to be evaluated, even if it was not a common practice. Immediately after the appearance of WSSV, farmers reduced stocking densities and all costs, including feeding, went down to a minimum. The 2001 price drop, which lasted until 2012, was particularly hard on shrimp farmers. Internal inflation rates and regulation costs also had an impact. An increase in productivity (Fig. 2), which leveled off in 2006, did not translate to an increase in profit. Beginning in 2006, increases in international oil prices and higher food demand in China and India led to an increase in raw material prices. There is a strong correlation between the price of the main raw materials used in shrimp feed and oil prices. This led to an 88 percent increase in feed raw material costs between 2004 and 2010 (Aguirre 2011). The main factor contributing to shrimp feed price increase during that period was the price of fishmeal. Fishmeal is not just a matter of feed cost, it is the main source of essential amino acids in many aquaculture feeds. Most shrimp farmers want a black pellet with a fishy smell. However, there is a high environmental impact associated with its use. Around 20 percent of all marine capture fisheries were used for fishmeal and fish oil production in 2014 (FAO 2016). Some estimates indicate that as much as 2-3 times the weight of wild fish in feed is used as the weight of farmed shrimp that is produced. However, the proportion of fishmeal used in feed for shrimp aquaculture has been declining from around 18 percent in 2005 to 9 percent in 2015. Furthermore, much of the fishmeal used nowadays in Ecuador comes from processing byproducts of fish for human consumption, mainly tuna. Alternative protein sources and amino acid supplementation was a response to the fishmeal price increase but it has had a beneficial impact on the environment. Feeds have evolved to maximize the advantage of growing genetically improved shrimp and feeding techniques have also improved. In the 2016 survey, 67 percent of respondents were feeding two times a day and 16 percent three or more times, 11 percent were using or testing automatic feeders, 16 percent were providing feed completely on feeding trays, and 44 percent were using feeding trays for controlling feed broadcast into ponds. Evolution of Production Practices It is difficult to make generalizations about the production techniques used during the past half century, mainly because there are no clear barriers between periods; it has been a continuum of gradual changes. Some periods are more or less homogeneous in the methodologies used. To summarize the changes in production strategies (Table 1), we considered eight periods: TABLE 1. Production strategies used in Ecuadorian shrimp farming. Period Stocking density Stocking type Feeding Chemicals Median production (PL/m2) (kg/ha/cycle) 1969-1984 2-7 Direct Natural productivity None 450 1985-1993 5-15 Direct/Nursery Broadcast Lime 650 1994-1995 10-30 Direct Broadcast/ Lime, antibiotics 550 Feeding trays 1996-1998 10-15 Direct/Nursery Broadcast/ Lime, antibiotics, 770 Feeding trays quaternary ammonium 1999 10-15 Direct/Nursery Broadcast/ Lime, antibiotics, quaternary 270 Feeding trays ammonium, pesticides, ozone, chlorine 2000-2005 5-12 Direct/Nursery/ Feeding trays Lime, quaternary ammonium, 360 Raceways probiotics 2006-2012 6-14 Direct/Nursery/ Broadcast/ Lime, probiotics 730 Raceways Feeding trays 2013-2016 6-17 Direct/Nursery/ Broadcast/ Lime, probiotics 1230 Raceways Feeding trays/ Automatic feeders (CONTINUED ON PAGE 42)
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