Effects of unilateral eyestalk ablation on ovarian histology and oocyte size frequency of wild and pond-reared Penaeus monodon (Fabricius) broodstock
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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.
CitationTan-Fermin, J. D. (1991). Effects of unilateral eyestalk ablation on ovarian histology and oocyte size frequency of wild and pond-reared Penaeus monodon (Fabricius) broodstock.
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ArticleWild immature Penaeus indicus females (11.5 ± 3.1 g body weight) were ablated by pinching, cautery or tying of one eyestalk, and stocked with control (unablated) females and males (9.2 ± 1.5 g) in a 12-m3 maturation tank. Full ovarian maturation and spawning were attained 4 days after ablation/stocking in all treatments, with a peak at 5–6 days. Seventy-five percent of ablated and unablated females spawned during the study period. Average egg numbers from complete spawns increased with size of females for all treatments. There was no significant difference in fecundity of complete spawns from the various treatments. However, hatch rates of unablated P. indicus were significantly higher than eyestalk-pinched females but not those ablated by cautery and tying. Similarly, survival after the 15-day period was lowest among pinched females.
ArticleRA Pudadera & JH Primavera -
Kalikasan, The Philippine Journal of Biology, 1981 - University of the Philippines Los BañosPrawns were subjected to the following treatments: blue light, red light, natural light, and natural light plus unilateral eyestalk ablation. Unablated prawns under blue and natural light developed stage III ovaries; under red light ovarian maturation reached only stage II. Ablation resulted in full maturation of ovaries and subsequent spawning. The external changes of the ovary were generally the same for both the ablated prawns under natural light and the unablated under different light qualities. Under blue light, however the ovary at stage III had numerous atretic cells and the diameter of its ova was more uniform. The maturation stage and mean gonadosomatic indices were high for the ablated and low for the unablated prawns.
The effects of diets on reproductive performance of eyestalk ablated and intact mud crab Scylla serrata The reproductive performance of female mud crabs was evaluated as affected by various diets. Dietary treatments were as follows: D1 — natural diet (mussel meat, squid, trash fish); D2 — combination of natural and formulated diets; D3 — formulated diet. Pond-sourced broodstock, with initial body weight of 300–400 g, were tagged in their carapace then stocked in three units of 10 m3 broodstock tanks at eight females per tank. Half of the females were ablated and the other half were intact. Spawnings were monitored and berried females were transferred to individual 500-l tanks for incubation of eggs. Four experimental runs were conducted. Broodstock response in terms of number of spawnings, spawnings with hatching, fecundity, egg fertilization rate, total zoea produced and broodstock survival was enhanced in females fed the mixed diet (D2) compared to those fed the natural diet (D1) or the formulated diet (D3). Larval quality measured as larval stage index followed the same trend. Results further showed that intact females fed diets D1 and D2 gave higher numerical values in reproductive performance and zoea growth index than ablated females while ablated females fed diet D3 performed better than their intact counterparts. This may be attributed to presence of essential nutrients and vitamins A, C, E in the formulated diet. Latent period from gonadal maturation to first spawning was shortened by eyestalk ablation. Use of a combined diet would ensure the production of good quality eggs and large numbers of zoea with the best chance of completing the larval stages and thus, would serve as an appropriate starting point in establishing a viable mud crab aquaculture.