INDUCTION OF GONADAL MATURATION OF POND-REARED MALE TIGER SHRIMP, Penaeus monodon THROUGH INJECTION OF GONADOTROPIN HORMONE

Very low naturally mating rate of pond-reared tiger shrimp broodstock is probably due to the slow maturation of the male stock. Eye-stalked ablation is a hormone manipulation which has been widely practised by commercial hatcheries in order to induce gonadal maturation female stock. However, this technique has several negative effects on the female stock herself. The aim of this study was to evaluate the salmon gonadotrophine releasing hormone analoque (SGRH-a) in stimulating the gonadal maturation of male stock of pond-reared tiger shrimp.  

The treatments were three dosages of SGRH-a at 0.01 (OV1); 0.02 (OV2) and 0.03 (OV3) mL/kg and control was eyed ablation (AB). The SGRH-a was administered via injection three times with one week  interval. Male stocks with average initial body weight of 82.1 g were randomly distributed into four of 10 tonnages concrete tanks, 26 male for each tank. A week after the last injection, males were electrically shocked to release their spermatophores from ampula terminalis. Variables observed were performances of spermatophores and profiles of amino acid and fatty acid of  muscle of the male stocks.

After induction, number of male maturing indicated by spermatophores releasing from ampulas terminal was higher in shrimp induced with OV1 (80.8%) compared to control ablation which was only 46.1%. Similarly, number of male releasing spermatopghore at rematuration was higher at OV1 group  (23.1%) than other treatments. Furthermore, shrimp treated OV2 had higher spermatophore weight around 0.16 g compared to control (0.11 g) and other two groups.

Total fatty acids content in muscle of male stocks after induction were increased with the increase of the SGRH-a dose of injection from 3.18% for OV1, 6.293% for OV2 and  7.234% for OV3 generally higher than control (eyed ablation) around  3.834%.