Increasing production in Korean shrimp farms with white-spot syndrome virus PCR-negative brood stock.

White-spot syndrome virus (WSSV) is a devastating, infectious virus affecting shrimp. Although sensitive techniques involving PCR have been developed to assist farmers in screening shrimp (brood stock) for WSSV prior to stocking ponds, such practices have not yet been applied in Korea. Despite the rationality of implementing screening, there has been some doubt as to whether the stocking of WSSV-PCR-negative fry epidemiologically decreases white-spot disease outbreaks. Here, we report a retrospective analysis of data from shrimp farms in the western coast of Korea where WSSV-PCR-negative brood stocks were used to stock rearing ponds. A total of 366 shrimp from Heuksan Island were sampled for WSSV with PCR. Of the tested shrimp, 7.2% (28 brood stocks) were identified as WSSV positive; only WSSV-PCR-negative shrimp were used for brood stocks. Total unit production (final shrimp production/ the area of the ponds) was higher, at 1.96, in ponds where WSSV-PCR-negative shrimp were used, as compared with 1.02 in other ponds in Korea in 2004. This retrospective analysis of WSSV in Korea may be useful to the shrimp aquaculture industry, suggesting a testable hypothesis that may contribute to the eventual control of WSSV outbreaks.