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May 30, 2013

Vietnam

Diseases in Lobster Cages, Again

 

Seafood.com Reports: For the second straight year, farmers raising spiny lobsters in Khanh Hoa Province are suffering huge losses due to high production costs and diseases.  In Van Ninh Commune, the number of lobster-farming households has decreased to 533 this from 800 last year, when the Commune operated 7,000 sea cages.   Even with lobster prices rising to around $57 a kilogram this year from $38.10 a kilogram last year, individual farmers are losing from $9,524 to $28,574 for each failed crop, depending on the number of cages being farmed.

 

During the 2011-2012 season, farmer Huynh Van Thuong stocked 5,000 lobsters, but lost 60% of them due to milky haemolymph syndrome (MHS, a bacterial infection), incurring a loss of about $28,574.

 

A farmer with approximately 5,000 lobsters in his cages has to invest over $100,000 to purchase juvenile seedstock and feed.  With the diminishing supplies of wild juveniles, prices for seedstock have doubled to $17.14 to $19.05 each.

 

Experienced lobster farmer Nguyen Van Vinh is converting part of his farm to fish culture.

 

Wikipedia Says: Spiny lobster has a complex larval development with many stages making it extremely difficult to produced seedstock in a hatchery.  Consequently, spiny lobster seed is collected from the wild using seiners, traps and divers.  The preferable size of the juveniles taken from the wild for aquaculture is between 4–6 centimeters.  Normally the best time to catch juvenile lobster is between May and November when the average size is 5–7 cm, while at other times of the year they are smaller than 2 cm.

 

Milky disease of lobsters developed in Vietnam in late 2006 and is assumed to be the result of poor quality handling and management.  The disease is likely to be induced by stress during handling and poor water quality during transport to farms.  Milky haemolymph has been experimentally transmitted among lobsters by cohabitation and by infection of unfiltered haemolymph from diseased lobsters into healthy lobsters.  Haemolymph filtered through a 0.45-μm filter is not infectious, which probably indicates the involvement of a pathological entity transmitted by either water or food.  The disease occurs in areas where there are concentrations of sea cages.  It caused a large decline in annual lobster production in Vietnam from 1,900 metric tons in 2006 to 1,400 tons in 2007.

 

Sources: 1. Seafood.com (an online, subscription-based, fisheries news service).  Editor and Publisher, John Sackton (phone 1-781-861-1441, email jsackton@seafood.com).  Central Vietnam’s Lobster Growout Farmers Suffering Diseases and Losses for Second Year.  May 24, 2013.  2. Wikipedia.  Spiny Lobster Culture in Vietnam.  Website Visit on May 29, 2013.

 

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