White Spot Disease, United States , April 23, 2004

Impact Worksheet

Summary:  The first identification of white spot disease (WSD) in the Pacific Ocean region of the US has been made in a commercial shrimp production facility on the island of Kauai in Hawaii.  On April 14 the Hawaii Department of Agriculture placed a quarantine on the affected facility prohibiting the movement of shrimp.  Prior to this outbreak, the only US reports of WSD had been off shore in the Gulf of Mexico and near shore in Texas, Mississippi, Georgia and South Carolina. 

White spot disease, caused by a virus, is found in many Asian countries including Japan , Indonesia , Republic of Korea, Malaysia , Thailand , Vietnam , the Philippines , and India .  In 1995 WSD was first reported in the US .  Since 1999, WSD has been reported in several Central and South American countries.

The US ranks 6th in terms of world production of shrimp and prawns.  Hawaii accounted for 14% and 5% of the value and quantity of total US cultured shrimp production in 1998 (latest available data), respectively.  Hawaii had 12 farms that produced shrimp in 1998.  Shrimp exports from Hawaii accounted for just under 1% of total US shrimp exports in 2001, both in terms of value and quantity. 

How extensive is White Spot Disease (WSD) in the United States (US), and what was the US ’ disease status prior to the outbreak?

The first identification of WSD in the Pacific Ocean region of the US has been made in a commercial shrimp production facility on the island of Kauai in Hawaii.  On April 14 the Hawaii Department of Agriculture placed a quarantine on the affected facility prohibiting the movement of shrimp.  Prior to this outbreak, the only US reports of WSD had been off shore in the Gulf of Mexico and near shore in Texas, Mississippi, Georgia and South Carolina.  The first documented occurrences of WSD in US commercial facilities were in Texas and South Carolina in 1995.  WSD has been found in wild shrimp and crabs off-shore in the Gulf of Mexico and near shore in Texas, Mississippi, Georgia and South Carolina during 1999-2002.  WSD is an OIE List B notifiable disease.

Source: OIE Disease Information Report, Handistatus II, Outbreak of Shrimp Viral Disease in Central America: Situation Report, June 1999, Fact Sheet for White Spot Syndrome Baculovirus Complex, Gulf States Marine Fisheries Commission, Hawaii Department of Agriculture News Release April 16, 2004, NR04-04

What is WSD?

WSD is caused by the white spot syndrome virus (WSSV) or white spot virus (WSV).  All decapod (Order Decapoda) crustaceans (shrimps, prawns, crayfish, lobsters and crabs) from marine, brackish, or freshwater sources are potential hosts for WSD. WSD was first reported in Taiwan and mainland China between 1991-1992, and subsequently found in many Asian countries including Japan , Indonesia , Republic of Korea, Malaysia , Thailand , Vietnam , the Philippines and India .  In 1995, WSD was reported in the US .  Since 1999, WSD has been reported in the following Central and South American countries:  Nicaragua , Guatemala , Honduras , Costa Rica , Panama, Mexico , Columbia, Ecuador , and Peru .

Clinical signs include shell spotting from abnormal deposits of calcium salts, and occasionally a reddish discoloration due to expansion of cuticular chromatophores. When farmed shrimp are infected, they become lethargic, stop feeding, swim slowly near the pond surface, and eventually sink to the bottom and die. Shrimp mortality can reach 100%.  No treatments currently exist for WSSV; therefore, shrimp farmers must rely on preventive management practices.

There are numerous potential transmission pathways for WSD.  Shrimp packing plants which process imported shrimp may discharge contaminated effluents into estuaries, thereby increasing risk of virus transmission to both wild and farmed shrimp.  In addition to discharged liquid effluent, solid waste material must also be properly treated (by heating) before disposal to prevent virus transmission.  Otherwise, sea birds could move the virus from landfill to shrimp farm by dropping or regurgitating undigested infected material.

Imported frozen shrimp to be used as bait for coastal fishing is also a hazard. Leftover bait shrimp that is discarded can be picked up by wild shrimp or crabs, thereby creating immediate risk for those populations. The same risk to wild crawfish exists when frozen imported shrimp are used for bait in inland fresh waters. Also, ballast water exchange, for example in the Panama Canal, may be a significant pathway for shrimp virus transmission to wild stock.

Other pathways by which virus can potentially be transmitted to aquaculture facilities include infected broodstock or contaminated vehicles or transport containers. Wild shrimp stock may serve as a vector to transmit WSSV to farmed shrimp via these pathways. Viral outbreaks in aquaculture facilities in turn heighten the risk for wild shrimp stock. Potential pathways for viral transmission from farmed aquaculture to native shrimp species include pond effluent, pond flooding, escape by infected shrimp, transport to processing facilities, use of imported shrimp as bait, sediment or solid waste disposal, and birds.

Source:  Aquaculture Magazine May/June 1999, vol. 25, n. 3; OIE; Outbreak of Shrimp Viral Disease in Central America: Situation Report, June 1999

What is the size of the shrimp industry in the US and Hawaii, and what are the shrimp exports from the US and Hawaii?

The most recent comprehensive state-specific data come from the USDA’s Census of Aquaculture in 1998.  According to these data, Hawaii accounted for 14% and 5% of the value and quantity of total US cultured shrimp production, respectively.  Hawaii had 12 farms that produced shrimp in 1998.  According to the Hawaii Agricultural Statistics Service, the total value of cultured food shrimp in Hawaii in 2002 was $4.7 million (personal comm.).  Shrimp exports from Hawaii accounted for just under 1% of total US shrimp exports in 2001, both in terms of value and quantity.  The state-specific export data are based on origin of movement, which is not necessarily the same state in which the product was produced; however in the case of Hawaii, it is reasonable to assume that most of the shrimp exported would also be produced in the state.  Commercial landings, i.e., wild-caught shrimp, were included in this table because aquacultured shrimp are only a small percentage of total shrimp production in the US .

Shrimp production and exports, US total and Hawaii

 

Aquaculture Production

Commercial Landings

Exports3
 

19981

20012

1998

20012

1998

2001

Value

($1,000)

            

   US total

12,188

27,808

NA

568,547

94,470

116,374

   Hawaii

1,709

NA

NA

NA

226

651

Quantity

(1,000 pounds)

            

   US total

4,217

7,953

NA

324,481

24,366

23,955

   Hawaii

197

NA

NA

NA

NA

218

Sources:  1USDA, NASS, 1998 Census of Aquaculture; 2NOAA, National Marine Fisheries Service. 2002; 3US total from World Trade Atlas, US Edition; Hawaii from World Trade Atlas, State Export Edition

What is the US ’ place in the international market for shrimp?

The US produced 150,697 metric tons of shrimps and prawns in 2001, accounting for 3.6% of world production.  This put the US in 6th place in terms of world production of shrimp and prawns. 

Source: United Nations FAO

CEI’s plans for follow up:

No follow-up is currently planned regarding the outbreak of WSD in Hawaii.  If you need more information or if you’d like to comment on this worksheet, you may reply to this message, or contact Judy Akkina at (970) 494-7324 or Chris Kopral at (970) 494-7325.