Comparison of ovary histology between different-sized wild and pond-reared shrimp Litopenaeus vannamei (=Penaeus vannamei)

Abstract

Summary Ovarian maturation of pond-reared and wild Litopenaeus vannamei (= Penaeus vannamei) broodstock was compared by analyzing morpho-histological characteristics. The number of spawns by each female was also considered to determine if successive rematurations can affect ovarian development. Individually tagged 42 wild and 47 pond-reared females were sampled at the end of a production period in a commercial hatchery. Morphological variables were recorded and ovaries were histologically evaluated for oocyte type and diameter. Although wild shrimp were bigger than pond-reared, no differences were seen in gonadosomatic indexes, either considered as a group or within stages of maturation. Differences between pond-reared and wild shrimp were observed in previtellogenic and early-vitellogenic oocyte distribution in vitellogenic and cortical stages. However, no differences were obtained in relation to the proportion of late vitellogenic oocytes and mature oocytes with cortical rods, or oocyte diameter in each maturation stage. Occurrence of atresia was negatively correlated to the number of spawns of each female, whereas gonadosomatic index and postovulatory follicles had a positive correlation with the number of spawns. Pond-reared broodstock appeared to have a normal maturation compared to wild Litopenaeus vannamei (= Penaeus vannamei) in our conditions. Successive spawnings did not seem to produce substantial alterations in the rematuration capacities of individual spawners in terms of the variables measured and the conditions of this experiment.