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December 7, 2013

Thailand

Gruenberg Rebuts Newman

 

Daniel Gruenberg, CEO of Acquestra (Thailand) Co., Ltd. (formerly Sea Garden Foods) and technical advisor to Sureerath Organic Products Co, Ltd., an organic farm and feed mill in Chantaburi, reports:

 

Stephen Newman’s recent article on inbreeding and genetics contains several factual errors and raises straw man arguments that he then proceeds to knock down with various unsupported assertions.  I would like to clarify my position on inbreeding and pond survival in general and go on to explain more specifically their relationship to early mortality syndrome (EMS).  Before I even get started on breaking down Dr. Newman’s assertions and claims, I would like to repeat that I have seen no claims that the cause of EMS is inbreeding.  Inbreeding is but one form of bad genetics that is and has always been clearly and unequivocally associated with poor pond performance.  EMS only serves to amplify this poor performance.

 

Let’s take a more in-depth look at the issues one by one:

 

Firstly, Dr. Newman’s claims that there is no relationship between inbreeding and weakened immunity and that there is no scientific data to support this. Further he even goes on to claim that there is little evidence that inbreeding even exists because professionally run breeding programs control it.  Anybody who spends time in the field and not in the laboratory knows that there are numerous ways for inbreeding to make its way into the postlarvae actually used in commercial production.  The most common way is for hatchery owners and managers to just use brothers and sister animals form the pond for the next season’s crop to lower their broodstock costs.  This practice is rampant in almost every country I have visited.

 

Dr. Newman also apparently fails to realize that every shrimp geneticist knows that even in a well run family-based breeding program that there is always a compromise between pond survival and growth.  When you select only the high growth animals, you will see a generation-by-generation decrease in pond survival.  Hence, even in a well-run genetic program, you can still force a weakening of shrimp immunity by merely placing the weighting of your selection criteria too much on growth and not enough on pond survival.  He also seems to ignore the papers published by Stephen Moss and Roger Doyle on documenting the link between inbreeding and decreased survival and pond productivity.

 

In sharp contrast to Dr. Newman’s claims, there are numerous studies that establish the linkage between poor productivity and inbreeding.  A few minutes with Google and the desire to know the facts will bring up sufficient data and studies, unless one has another agenda I wonder why such false claims would be published.

 

Secondly, I think Dr. Newman doesn’t fully understand the microbiology of EMS.  He claims that Vibrio parahaemolyticus colonizes the “chitinous surfaces of the stomach”, but the epithelial layers of the prawn’s stomach do not contain any chitin.  He also claims that the toxin damages the hepatopancreas (HP).  It appears quite hypocritical to this author that while Dr. Newman lambasts unsupported claims on one hand, he goes on to make pure speculation on the mechanism of EMS pathology.  Based on historical experience with other environmental hepatotoxins, the damage from the toxin is likely not due to any direct action of the toxin per se, but actually is a result of oxidative stress as a by-product of the HP’s detoxification mechanisms that utilize free-radicals to break down the toxin.  In any case, to date, no studies have been published on the details of this mechanism, so any claim one way or another is merely the unsupported speculation that the article is trying to discredit in the first place.

 

Thirdly, Dr. Newman goes on to further speculate that immunology has nothing to do with genetics.  A claim that is preposterous.  Shrimp immunity involves antimicrobial peptide genes such as penaeidin, anti-lipopolysaccharide factor, and crustin.  The free-radical production system also uses enzymes all under genetic control.  There are potentially numerous other mechanisms of resistance such as those in the past that have shown resistance to previous viral penaeid diseases and many that surely remain to be discovered and studied.

 

The industry indeed would be better served by sticking to facts and not speculation and despite his claim to the contrary Dr. Newman’s article is replete with multiple naked speculations and claims with not only no scientific basis, but he even goes further to contradict well known and established fact and scientific data.

 

Information: Daniel Gruenberg, Sureerath Prawns, 105 Moo 13 Paknam, Laemsing, Chanthaburi, Thailand 22130 (phone +66-39-363075, mobile +66-87-059-7528, Skype danielpattaya1, fax +66-39-363721, email daniel@sureerathprawns.com, webpageshttp://www.sureerathprawns.com and http://www.eopathailand.org).

 

Source: Email to Shrimp News International from Daniel Gruenberg.  Subject: Stephen Newman’s Straw Man.  December 7, 2013.

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