The problem of early mortality syndrome (EMS) may be worse in Eastern Thailand than is being reported, according to discussions between experts on Shrimp News International.
Last week an estimated 80% of shrimp ponds in the key production areas of Pattaya, Rayong and Trat Province were dry, reported Daniel Gruenberg, CEO of shrimp-farming operation Sea Garden Foods.
Although it is January, Gruenberg said that most large, well-run farms should be stocking at present, and expressed concern that they were empty.
“Are we ostriches with our heads in the sand, hoping that the early mortality problem will just go away?” he asked.
“In my opinion, the recent EMS symposium in Bangkok reported on a lot of nonsense theories, and I don't see the proper steps or research being taken to get a handle on this problem.”
He also said that a contact in Chantaburi Province was seeing up to 90% of ponds dry, and that he knew processors who were struggling to get hold of product.
Another issue raised by Gruenberg was that the three largest hatcheries in eastern Thailand had confirmed EMS was killing broodstock after just 20 or 30 days in the hatchery, news which came as a surprise to some and was debated by others.
He pointed out that this would worsen the problems caused by EMS when some farms came to re-stock in February, only to find broodstock depleted.
There is published evidence that inbreeding can negatively affect traits such as disease resistance and other fitness-related traits in shrimp
“I am afraid that this problem is getting much bigger than most are willing to admit,” he said.
The discussion moved on to what caused the EMS outbreak, with the consensus being that there is still no concrete knowledge on the subject.
One difficulty in finding the cause was pointed out by an Indonesian farmer, who asked why farmers who had been successful in their management techniques for years were suddenly having disease problems.
“So far EMS has not been reported in Indonesia, but it could be here and we don’t know about it,” he said.
“The exchange of information among shrimp farmers is rather guarded here, and most failures would be covered up as neatly as possible by pond owners and industry suppliers.”
Leland Lai, director of aquaculture feed supplier Bio-Marine Aquafauna, suggested EMS was likely to be an as-yet unidentified virus, a toxin in plankton, or a genetic loss caused by inbreeding.