Effects of unilateral eyestalk ablation on ovarian histology and oocyte size frequency of wild and pond-reared Penaeus monodon (Fabricius) broodstock

Abstract

Effects of eyestalk ablation on ovarian maturation of wild and pond-reared Penaeus monodon were determined to compare their reproductive potential. This was done by counting the oocyte size frequency in four regions of the ovary and comparing the percentage of each cell type present at each stage of maturation per group. Sampling of ablated prawns was done during three maturation or spawning periods within the first molt cycle after ablation. It took 5 and 14 days for wild and pondreared prawns, respectively, to show signs of ovarian maturation after ablation. Percentage of proliferating cells, the smallest germinal cells in the prawn ovary, was higher in wild unablated (8.3%) than ablated (2.5–5.0%) groups. Significant differences were observed in all cell types at different stages of maturation. In both unablated and ablated prawns, there was a uniform development of the whole ovary and similar occurrence of atresia at all stages. The presence of bigger oocytes in the ovaries of ablated prawns sampled after spawning provided histological evidence for lower number of eggs per spawn and faster rematuration.