Shrimp farming in Mexico has suffered significant losses in the past years due to white spot out breaks. This, together with local weather limitations, forced farmers to modify their operational systems; including an additional phase. They developed new technology to manage raceways/nurseries, which allowed them to take better care of the PL's in the first stages of the transition from hatcheries to farms and deliver a stronger animal to the ponds. This paper discusses not only the evolution and outcome of this process and the potential of the use of this technology in South East Asia under EMS/AHPND conditions but also the benefits of the use of this technology beyond EMS/AHPND as a way to manage risks improving production and reducing costs.

It has been seven years of technology development that led the industry to improve the design of these systems and their management. The use of better quality feeds and probiotics has played a key role in increasing survivals and extending the residence time in the raceways/nurseries thereby improving nutrition and maintaining water quality.

Today the technology has expanded to Latin America. Most of the industry stocks in raceways/nurseries, keeping animals for an average of 30 days with stocking densities between 2 to 12 Pl/liter, with survivals of 70% to 90% and with final weights of 0.3 to 2 grams. These animals after transfer to the ponds can achieve 6 to 8 grams at DOC 30, due to the compensatory growth in vannamei, compared to 3 to 4 grams if stocked directly. Cycles are reduced by 20 to 30 days and FCR's are reduced by 10 to 30%, which increase significantly the annual productivity and profit of the ponds and reduce the risk of disease outbreaks.

Mixed results have been reported in the different countries in SEA using this technology, however several groups have been able to effectible transfer and adapt it, improving significantly the success rate of the grow out ponds and managing better the risk. Large groups in Mexico, Thailand and Vietnam are taking these system one step further building complete grow out systems under this model.

In challenging times with the presence of new diseases or adverse environmental conditions the industry needs to change and use new tools. Considering that the cause of EMS/AHPND is now known, and the fact that the different strains of Vibrio are stage specific pathogens, the use of raceways may be an alternative tool for all countries. The farmers can focus on keeping the Vibrio excluded in a smaller space, avoiding the EMS/AHPND infection during the traditional mortality period of up to 30 days and also get the other benefits from using this technology. Additionally, with the shrimp price drop, a significant reduction on two of the major costs in shrimp farming, days of culture and FCR's, is the only way to compete and still run a profitable business in the future.