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April 5, 2013

 

Saudi Arabia

Update on the Whitespot Situation from Laurence Evans

 

To add some context to your report on Saudi Arabia, 2013 is what may be termed a transitional year for shrimp farming in Saudi Arabia.  Of the six farms that were in production when whitespot hit Saudi Arabia, two have already started restocking their ponds for this summer (Gazadco and Saudi Fisheries), one is doing “experimental work” on a fairly big scale (National Prawn Company), one has not restarted (Arabian Shrimp Company), one is planning only fish culture (Red Sea Aquaculture) and one is building a hatchery to produce its own shrimp (Island Prawn).  Additionally, the government is monitoring trials on the introduction of SPF shrimp (Litopenaeus vannamei).

 

One weakness of the Saudi shrimp industry is that pumping is required to maintain salinity, so zero exchange type systems cannot be implemented.  Whitespot is more closely correlated to low winter temperatures than to rainfall.  The weather changes that lead to large rapid drops in pond temperatures, sometimes bring rains, but more often (90% of the time), they bring only cold winds and dust storms that cause pond temperatures to plummet from 28°C to 20°C over 24 hours.  In the article that you referenced, M.R. Kitto said the dust storms that accompany the cold could be a stress contributing factor.  That’s a definite possibility, but there are no published reports that wind-born iron, manganese, copper and cadmium are a problem in Saudi shrimp farming.  These elements are likely not to exceed the levels required for algae blooms to flourish.  Kitto advises that the current situation is a warning lesson for future shocks, but the current outbreak has been so devastating that it is difficult to imagine a worse scenario than the total closure of every shrimp farm in Saudi Arabia.  The problem faced by all farms in Saudi Arabia is how to produce shrimp when the plankton contains the whitespot virus and even rotifers are testing positive for it.  While pumping seawater is essential to maintaining salinity, it also turns out to be the biggest risk factor once our biosecurity practices are in place.  It is not practically feasible to filter incoming water to the size of infected rotifer eggs, let alone to the micron size to remove rotifers.  As suggested by Kitto, Island Prawn is attempting to transform its farm to wellpoint-sourced seawater.  This solution, however, is not possible for every farm due to the volumes of water required and the local geology.

 

Source: Laurence Evens (ecotao@yahoo.com).  Email to Shrimp News International.  Subject: Reference Saudi Arabia—Shrimp Industry Wiped Out—Job.  April 5, 2013.

 

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