Development of ovarian maturations in orange mud crab, Scylla olivacea (Herbst, 1796) through induction of eyestalk ablation and methyl farnesoate

Abstract

Many crustacean species including mud crab, genus Scylla are incapable of natural maturation under captivity, thus putting high pressure on the wild catch. Therefore, to increase the availability of mature broodstocks in captivity, this study determined the effect of Eyestalk Ablation (EA) and Methyl Farnesoate (MF) administration on ovarian maturation stages of the orange mud crab, Scylla olivacea. The study was conducted using a control group (T1) consisting of 95% alcohol (widely used as a chemical solvent), and three treatment groups consisting of: 5 µl/g oral administrated MF in the diet (T2), EA (T3) and a combination of both treatments of MF and EA (T4). The highest percentage of ovarian maturation Stage 4 was found in the T4 treatment (20.8%) compared to the other treatments which were T1 (0%), T2 (8.33%) and T3 (12.5%). Ovarian development of the treated groups (T2, T3, and T4) was significantly different compared to the control group (T1) (p < 0.05). However, there was no significant difference observed in the mean Gonadosomatic Index (GSI) in orally administrated MF (T2) compared to the EA group (T3) (p > 0.05), but it was significantly different when compared to the combination group of MF and EA (T4) (p < 0.05). It can be concluded that the combination method of oral administration of MF through diet and EA (T4) is the best technique for producing mature ovaries.