Hematological parameters in relation to sex, morhometric characters and incidence of white spot syndrome virus in tiger shrimp Penaeus monodon Fabricius, 1798 from Sunderban, West Bengal

Seasonal influence on the hemato-immunological parameters and prevalence of white spot disease (WSD) in wild-caught tiger shrimp, Penaeus monodon was studied. A total of 210 specimens of P. monodon were collected from the Sunderban estuarine mangrove ecosystem during pre-monsoon (March to May) and monsoon (June to September) seasons in 2010. The animals were sexed, measured (total length and carapace length) and weighed. The hemato-immunological parameters such as total hemocyte count (THC), granular hemocyte (GH) and nongranular hemocyte (NGH) count, phenoloxidase activity and serum protein levels were analysed. The animals were diagnosed for WSSV by nested polymerase chain reaction (PCR). Significant difference (p<0.01) in THC, GH and NGH count was observed between seasons in both sexes. However, no significant difference was noticed in serum phenoloxidase activity and serum protein level in both sexes between seasons. None of the animals were diagnosed positive for WSSV in first step PCR throughout the study period. However, few samples were diagnosed positive in the second step PCR in the month of September. No significant difference was observed in any of the hemato-immunological parameters studied, between second step positive and negative samples, which suggests that level of infection in the second step PCR positive samples might not be sufficient to alter the immunological parameters.