Histopathological studies on wild broodstock of white shrimp Penaeus vannamei in the Platanitos area, adjacent to San Blas, Nayarit, Mexico

In Mexico, the capture of wild broodstock of Penaeus vannamei or P. styliro stris for hatchery production of postlarvae is a common practice. During Se ptember 1995 and March-April 1996, high mortalities were observed in the wi ld broodstock captured in the Platanitos area, on the coast of San Bias, Na yarit, Mexico. As a result of these mortalities, many hatcheries closed dow n their facilities. Because early histological analysis had shown that some of these animals were infected with different pathological agents, such as bacteria and viruses, the present study was carried out to determine the p revalence and severity grade of infectious diseases affecting these shrimp. During March 1996, a total of 28 female and 28 male shrimp were randomly s elected from a recently captured stock of 600 breeders of P. vannamei. A se cond sampling (28 females and 28 males) was performed from a stock of 800 b reeders captured in April 1996. On this occasion, the shrimp were sampled a fter 10 d of acclimation in a hatchery. The animals selected for examinatio n were those with necrosis in the cuticule, red coloration in the telson an d uropods, soft cuticle, empty gut, and erratic swimming. All of the specim ens were subjected to histological analysis and dot blot hybridization with a gene probe specific for Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV). The results showed that both stocks were infected with at l east three different viruses (Infectious Hypodermal and Hematopoitetic Viru s, Taura Syndrome Virus and Hepatopancreatic Parvo-Like Virus), gram-negati ve bacteria and other parasites such as gregarines. It is likely that the h igh mortalities observed are due to the recent introduction of TSV in the w ild population of P. vannamei.