On the road to solving the high mortality in freshwater prawn hatcheries in Myanmar and Bangladesh  

Freshwater prawn (Macrobrachium rosenbergii) production is an important aquaculture sector in both Myanmar and Bangladesh and both countries have a history of local prawn post-larvae (PLs) production. Myanmar previously had about 21 hatcheries with annual production ranging from 200 to 400 million PLs; by 2007, Bangladesh had 81 prawn hatcheries. In 2015, only a handful of hatcheries were still functioning in Myanmar with mixed results. A joint study by Winrock International and KATALYST in 2012 reported that the demand of prawn PL in Bangladesh was at least 1,000 million but the supply was only 200 million from the wild (despite a government ban) and 30 million from hatcheries. Many hatcheries in Bangladesh are now closed or only producing occasionally. Hatcheries in both countries are experiencing issues with high larval mortalities with inconsistencies in production and often a hit-and-miss production resulting in major economic losses. In 2015, Winrock International requested assistance in both countries through the USAID farmer-to-farmer program. Winrock and many other programs had previously tried to solve the problem with mixed results leaving farmers at a loss.

In Myanmar, support was also provided through the USAID activity "Developing a sustainable seafood industry for Burma" (Cooperative agreement AID-482-A14-00003) during an initial visit to Myanmar followed by the Winrock activity to work directly with Kyauk Tan hatchery located on Aung Moe Khine soft-shell crab farm and other hatcheries. Previous PCR and RT-PCR tests for WSSV, MrNV and AHPND/EMS conducted at the University of Arizona's Aquaculture Pathology lab on prawn larvae samples were negative. Previous lab tests conducted in North Carolina and locally in Myanmar were positive for Aeromonas sp., Vibrios and other bacteria as well as epibionts, etc. Hatcheries use the clear water Thai style method with water exchange, wild broodstock, seawater (or hypersaline water) mixed with fresh water, antibiotics (usually OTC, but also Rhodomycin) from the start of hatchery cycle and Artemia followed by locally-made supplemental feeds. Similar practices are also used in Bangladesh but on a larger production scale.

Farmers in both countries claim that the high mortality problems began around 2012 and the same hatcheries had previously been successful. While this date may have some significance, it appears that much of the problem relates to hatchery management, particularly with respect to water quality management and solids removal, feeding practices and biosecurity protocols. Because farmers often change water and wild broodstock sources, it is difficult to pinpoint potential causes but increasing pollution in local waterways may be a contributing factor leading to importation of bacteria and other potential diseases.  Use of properly designed recirculating systems and good biosecurity and feeding practices will likely resolve many problems.