32 MARCH 2018 • WORLD AQUACULTURE • WWW.WAS.ORG The shrimp farming area in Mexico was given as 72,000 ha by the Secretaria de Aguicultura, Ganaderia, Desarrollo Rural, Pesca, and Acuaultura (courtesy Scott Horton, private consultant, Los Mochis, Mexico). About 2 percent of the area (1,440 ha) is in extensive production, and that most of the remaining area is semiintensive production. The Brazilian Shrimp Producers Association reported 25,000 ha of shrimp ponds in Brazil.3 The majority of ponds are for semiintensive or intensive production. Fifteen percent of farms are operated by small producers, and some use extensive production, but there probably are no more than 1,000 ha of extensive ponds. There are several other countries for which pond areas were obtained to include Honduras, Nicaragua, Panama, Iran, Peru, Sri Lanka, Madagascar, Colombia, Mozambique, Cuba, Costa Rica, Belize, Guatemala, Australia, El Salvador, New Caledonia, and the United States. The authors know that several countries have only semi-intensive and intensive production. They also know that other countries have very little extensive production, and the area was assumed to be 10 percent of the country-level shrimp pond areas. We estimate a combined shrimp pond area of 2,131,100 ha in 30 countries, accounting for all but 8,878 t of global shrimp aquaculture production in 2015 (Table 3). Using the average yield for these countries, there may be an additional 4,000 ha of shrimp ponds in the other 20 or so shrimp-producing countries, making the global pond area about 2,135,100 ha. The country-level areas along with the probable areas in extensive culture (done without feed) was roughly 983,100 ha. The estimate of the extensive area seems reasonable, because the 2016 Alltech Feed Survey indicated that 39,900,000 t of aquaculture feed were used in 2015, and the 2018 Alltech Feed Survey reported that 15 percent of aquaculture feed was for shrimp. Assuming the percentage of shrimp feed was the same in 2015 as in 2017, about 6,000,000 t of feed were used for shrimp in 2015. The average FCR for shrimp (L. vannamei and P. monodon together, but adjusted for differences in total countrylevel production of the two species) in Thailand, Vietnam, India, and Indonesia was 1.42 (Boyd et al. 2017; unpublished data). At this FCR, the amount of shrimp feed used in 2015 would produce about 4,225,000 t of shrimp. This is about 650,000 t less than total global shrimp production reported for 2015 by FAO. The yield for 650,000 t from 983,100 ha would be 0.660 t/ha/yr. This is slightly greater than expected because references such as Nhuong et al. (2002) and Akber et al. (2017) place yield of extensive shrimp production (no feed) at less than 500 kg/ha. However, these estimates usually indicate that only one crop is produced annually, but intensive farms often produce two crops per year. Of course, feed production data from the Alltech Feed Surveys are only estimates, and these data are the basis for the estimation of average yield by extensive production. Production of shrimp by extensive culture likely resulted in around 13.3 percent of global production, but it used an estimated 46.0 percent of the production area. The benefits to land use for semi-intensive and intensive production ponds instead of extensive ponds is obvious. It is feasible to produce 10 to 20 t/ha per yr of shrimp through intensive production, but even at a global average of 5 t/ha per yr, the global shrimp production of 2015 could have been achieved with about 975,000 ha of ponds. Land Use to Support Pond Area Shrimp farms require land to support the production pond surface area upon which the estimates of pond area in Table 3 are based. The support area includes land for embankments, reservoirs, canals, settling basins, roads, staging areas and storage. The average, additional farm area necessary to support production ponds was found to be 48 percent of pond water surface area (Jescovitch 2016). Thus, the estimated global shrimp pond area should require about 1,024,850 ha of additional support land on farms. Agricultural land is used to produce ingredients for shrimp feed. Chatvijitkul et al. (2016) found shrimp feeds to have an average of 0.240 ha of embodied land per metric ton of feed. Thus, the 6,000,000 t of shrimp feed used in 2015 carried an embodied land use of around 1,440,000 ha. The total land use for global shrimp production estimated as pond area + support area on farms + embodied land in feed was probably around 4,599,960 ha, and 31.3 percent was embodied in feed. The land use is 0.94 ha/t shrimp. Land Use Benefits of Intensification Increasing average global yield to 5 t/ha per yr would reduce total land use to about 2,883,000 ha, with 49.9 percent of the area being land embodied in feed — total land use of 0.59 ha/t shrimp. The area of land used for production of feed ingredients does not decrease with intensification; it will increase in proportion to shrimp farm land use as production intensity increases. However, greater land use for production of feed ingredients is potentially less threatening to biodiversity than expanding shrimp farming in coastal areas (Boyd and McNevin 2016a,b). The main opportunity to reduce the area of land embodied in feed is to reduce FCR through better feed management. Reducing FCR by 0.1 unit will reduce feed use by 100 kg/t of shrimp. A 0.1 reduction in the global FCR for shrimp production in 2015 would have reduced feed use by 600,000 t and reduced embodied land for feed by 144,000 ha. At present, there appears to be two shrimp-farming sectors: a feed-based sector with relatively high and consistently increasing yield, consisting primarily of L. vannamei and P. monodon production, and an extensive sector that focuses on low-intensity production of P. monodon and a few other penaeid species. This scenario likely will not change in the near future, but possibly the global area, but not global production, by feed-based aquaculture will decline because of intensification. There are also two general and different mindsets that dominate discussions around the sustainability of shrimp farming: 1) low-intensity shrimp farming has less impact because it requires fewer inputs and 2) higher-intensity shrimp farming produces more shrimp with less resources per unit of production. These views are fueled by representatives of industry sectors advocating their system type to promote their product. There are indeed trade-offs for both production systems, but advocacy for low-intensity shrimp farming often is coupled with the goal of reducing shrimp consumption. Although there is no nutritional requirement per se for shrimp in human diets, reducing shrimp consumption seems unlikely given increasing demand associated with the rise of the middle class in China, India and other rapidly developing countries, and ineffectual attempts to convince people to alter their diets towards lower-impact foods. Competition for natural resources will continue to grow as the world produces more food. Prioritization and valuation of
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