Effect of vertebrate steroid hormones on the ovarian maturation stages of orange mud crab, Scylla olivacea (Herbst, 1796)

Abstract

Orange mud crab, Scylla olivacea soughted as delicacy because their flesh is tasty and has high quality which boosted its commercial value in Malaysia. This studies focused on S. olivacea ovarian maturation after the introduction of steroid-based hormones i.e. 17α-hydroxyprogesterone (17α-OHP) and 17α-hydroxypregnenolone (17α-OHPL). The effects brought by these hormones were explored through external morphology, histology of oocyte and haemolymph hormone expressions. The crabs, S. olivacea were collected from Kuala Muda, Kedah on the West Coast of Peninsular Malaysia (5°39′N 100°19′E). After brief incubation, the crabs were introduced with treatments (through injection) of 95% alcohol (μl/gBW), 17α-OHP (0.01μg/gBW and 0.1μg/gBW) and 17α-OHPL (0.01μg/gBW and 0.1μg/gBW). During the treatment period, ovary coloration, gonad somatic index (GSI), oocyte diameter, oocyte structure and, levels of 17α-OHP as well as 17α-OHPL in haemolymph were collected every 10days throughout the 60days of treatment. Crabs injected with 95% alcohol showed negligible signs of ovarian maturation compared to those injected with hormones. However, crabs injected with 17α-OHPL showed increased ovarian maturity, produced the highest GSI (2.51±0.72%) and produced large oocytes (diameter=178.63μm) with uniform development compared to crabs injected with 17α-OHP. In addition, decreased 17α-OHPL concentrations in the crab's haemolymph signifies utilization (of this hormone) to produce oestrogen. Hence, the findings obtained from this study depict fundamental biological information of the crab, S. olivacea. Nevertheless, the use of matured female S. olivacea is highly recommended for better results. Statement of relevanceThis article is suitable with Aquaculture Journal because the findings will give a big contribution in mud crab aquaculture. Mud crab seedling especially Scylla olivacea is getting less landing every year, new approach needed in ensuring enough supplies of S. olivacea to be available. Using hormone in this study article would help the hatchery production of S. olivacea to increase.