Black tiger reaction to EMS offers clues on disease

　　

　　October 9, 2013, 11:12 am

　　

　　Eva Tallaksen

　　

　　The reaction of Black tiger, or Penaeus monodon, to the early mortality syndrome (EMS) bacteria can offer some clues into the disease, said speakers during a panel at GOAL 2013 in Paris.

　　

　　Noriaki Akasawa, managing director of the Malaysian shrimp farm Agrobest, said black tiger shrimp were never infected by EMS, even if they were raised in the same ponds as infected vannamei. However, black tiger are susceptible to EMS, said Robins McIntosh, of Charoen Pokphand Foods.

　　

　　“Black tiger seems to survive much better,” he said. But while it doesn’t die in the ponds, “if you feed it the bacteria, it dies.”

　　

　　What goes on there is one of the many clues to EMS that are needed to explore, said McIntosh. Another clue, he said, involves tilapia. The mortality of shrimp from EMS declines if you have tilapia in the water.

　　

　　“That’s a clue there.” The EMS bacteria has also been found to be highly sensitive to salinity, and does not survive well in high salinity areas, he said.

　　

　　Akasawa — who was credited by GAA’s president George Chamberlain for having discovered the effect of high PH on EMS, and for having Asia’s ”best managed” farm and thorough data collection — detailed how his farm had been hit by two EMS outbreaks, one in late 2010/early 2011, and another in mid-2013.

　　

　　The first outbreak was serious, but production recovered and was gradually re-established to 85p/square meter, with 80-95% survival rates, he said. In comparison, the second outbreak was far worse, and the mortality was much slower.

　　

　　With Thai production levels due to fall to less than 300,000 metric tons this year, to around 280,000t, predictions as to its recovery are anyone’s guess. The most optimistic scenarios, according to a slide by McIntosh, foresee a recovery to 600,000 by 2017, whereas the pessimistic outlooks predict volumes of just above 300,000 by 2017.