Abstract
Researchers from the U.S. Marine Shrimp Farming Program (USMSFP) have developed novel approaches to mitigate the devastating impact of shrimp viruses, including the use of specific pathogen free (SPF) and specific pathogen resistant (SPR) shrimp, as well as the establishment of biosecure production systems that rely on pathogen exclusion. These approaches have evolved over the past decade in response to changing disease problems faced by U.S. shrimp farmers.
In the late 1980’s and early 1990’s, U.S. farmers observed Runt Deformity Syndrome (RDS), an economically significant and frequent disease problem of cultured Pacific white shrimp, Litopenaeus vannamei. RDS is characterized by reduced growth rates and cuticular deformities and is caused by Infectious hypodermal and hematopoietic necrosis virus (IHHNV). The increasing incidence of RDS on commercial farms catalyzed USMSFP researchers to develop SPF stocks of L. vannamei that were free of IHHNV. High health offspring from these SPF stocks were made available to U.S. shrimp farmers, resulting in a significant increase in U.S. farmed shrimp production from 1992 - 1994.
However, in mid-1995, Taura syndrome virus (TSV) was identified in south Texas, the major shrimp farming region in the U.S., and the resulting TSV epizootic contributed to a 164% decline in Texas shrimp production from 1994 to 1995. USMSFP researchers responded by initiating a selective breeding program to develop TSV-resistant L. vannamei. The use of these high-health SPR stocks, in conjunction with on-farm biosecurity practices, resulted in incremental increases in U.S. shrimp production from 1998 to the present.
Although TSV-resistant shrimp improved production and profitability for those farmers who were experiencing crop losses from TSV, breeding shrimp for resistance to a single viral pathogen, using current selective breeding strategies, may not be the most effective course of action for the long-term viability of the shrimp farming industry. USMSFP researchers are now developing biosecure shrimp production systems which rely on pathogen exclusion, and research results indicate that it is possible to produce > 5 kg of market-sized shrimp (~ 20 g) per m2 of raceway in about 12 weeks, using < 400 L of water per kg of shrimp.
With advanced biosecure technologies available, the U.S. shrimp farming industry will be able to expand into areas away from the coast with greater control against the spread of disease and without adversely affecting the environment.
