Studying severity of infection of indigenous shrimp (Penaelts semisulcatus) with the internal protozoan Gregarine in Bushehr, southern Iran

Infection of green tiger shrimp that caught in the coastal waters of Bushehr and those used as breeders in the region with the protozoan Gregarine studied over the years 1979- 2003. The specimens of the shrimp in the area sampled and examined for the infection. Of the eight female and two male shrimp specimens examined in the year 1979, all were infected with Gregarine that was in trophozoite (90%) or gametocystic (100%) state or both. Of the five female and six male shrimp specimens examined in the year 1994, all were found to be infected with the protozoan in trophozoite (18.18%) or gametocystic (90.9%) state. Of the 14 female shrimp specimens examined in the year 2003, we found that only two were infected with the protozoan that was only in trophozoite state which was 14.28 and gametocystic was 0. Infection of the shrimps in different length classes with the protozoan was found to be decreasing, going down from 87.5% in the length class 116-125 cm to 50% in the length class 186-195 cm.