Early Shrimp Mortality
Linked to Water pH

Research at a large shrimp farm in Malaysia indicates that the trigger for early mortality syndrme (EMS) is an increase in water pH to 8.5 to 8.8. The shrimp farm studied produces shrimp in 461 plastic lined pools.

EMS first appeared at the farm in January 2011 in five of the ponds stocked with post larvae from the same hatchery. After two months the disease had spread throughout the farm. Typically mortality in the effected ponds was 70% to 80%, and all ages and sizes were affected.

Water quality tests and replicated aquarium trials with controlled levels of various pararmeters confirmed that the disease repeatedly regressed at lower pH (around 7) and manifested at higher ph of 8.5 to 8.8. Survival rates were improved with management of pH .

Six weeks earlier research at the University of Arizona reported that the disease was caused by a bacterial agent. EMS has had a significant impact on shrimp production in southeast Asia. The research results will provide a tool for farmers to address the pH and manage the disease.