World Aquaculture September 2018

WWW.WA S.ORG • WORLD AQUACULTURE • SEP TEMBER 2018 37 ( C O N T I N U E D O N P A G E 3 8 ) small (100-5000 m 2 ) and are managed with fertilization, control of physical-chemical parameters of the water, use of extruded feed and a sex ratio of three females to one male. Fry are collected from ponds with nets periodically (daily, weekly or biweekly). There are also some hatcheries for reproduction, incubation and nursing that are used only by companies with higher levels of investment and that have recirculating systems, incubators, biofilters and disinfection systems with ultraviolet light. Fry marketed for cultivation in the indicated departments are mostly male monosex and come mainly from private and state companies. There are more than 30 hatcheries that produce sex- reversed male fry and fingerlings, of which only four are formally registered. Among the regions where sex reversed fry are produce and of which the clear majority are not authorized, there are more than ten producers in San Martín and between one and two producers each in Chincha, Tingo María and Jaén. Hormones most commonly used in the process of sex reversal from females to males are 17-alpha methyltestosterone and mesterolone. These are commonly found in local markets and have different provenances, costs and levels of purity (Table 3). Grow-out Systems Tilapia are produced in monoculture or polyculture in earthen or concrete ponds and rarely in cages, and are supplied with high- quality feed. In Peru, the most common tilapia production methods are: • Extensive, where tilapia are stocked as mixed-sex fry and at a low density in earthen ponds, which are usually managed by families that grow fish for household consumption or local marketing; • Semi-intensive, which uses sex-reversed fry, fed with balanced feed and water is fertilized with organic or inorganic fertilizers to provide supplementary natural foods and improved water productivity; • Intensive, where sex-reversed fry are used. Greater stocking densities are managed, and high-quality balanced feed is used, where the natural productivity of the environment plays a secondary role, contributing in some cases to improved feed conversion. In terms of infrastructure and equipment, ponds are commonly used and to a lesser extent floating cages and lined tanks, and recently ponds with recirculation systems and paddlewheel aerators. TABLE 3. Main hormones used for sex reversal of tilapia in Peru. Hormone Origin Purity (percent) Sex reversal efficiency Price (S/.) (percent) 17alpha- methyltestosterone China 99.8 95-98 363.64 17alpha-methyltestosterone Brazil 90.8 85-90 181.82 mesterolone Germany 99.8 98 545.45 TABLE 4. Tilapia imports to Peru from various countries by value (expressed as FOB in thousands of US dollars) and net weight (in t ) (Source SUNAT import information, September 2016). Product type/origin FOB Value (US$) Net weight (t) 2012 2013 2014 2015 2016 2012 2013 2014 2015 2016 Frozen China 2,938.04 5,721.42 8,404.43 5,401.49 5,675.63 849.24 1,601.36 2,086.32 1,551.44 1,844.99 Vietnam 69.31 161.45 399.29 190.75 21.92 42.02 118.00 61.00 United Kingdom 76.03 24.00 Ecuador 78.39 101.93 37.80 42.05 12.60 11.26 13.60 4.23 4.59 1.36 United States 110.13 19.07 Canada 2.00 3.00 Fresh Ecuador 2,259.82 1,927.65 1,508.66 1,679.53 1,047.18 308.33 243.14 178.50 190.59 118.49 China 105.80 469.17 20.00 80.70 Colombia 12.89 101.38 1.40 12.18 Frozen Fillet/Whole China 93.05 109.37 324.54 68.18 21.50 21.32 66.18 22.00 Ecuador 42.32 21.80 5.67 2.50 Colombia 120.82 279.37 14.76 33.83 Grand Total 5,480.92 8,102.63 11,093.43 7,846.89 7,070.37 1,217.92 1,916.32 2,461.59 1,930.79 2,071.84