నైరూప్య

EYE STALK ABLATION OF FRESHWATER CRAB, BARYTELPHUSA LUGUBRIS: AN ALTERNATIVE APPROACH OF HORMONAL INDUCED BREEDING

Rana S

Eyestalk ablation now a days is considered as the most effective method to facilitate molting and maturation, but its physiological responses is still not clearly studied in Barytelphusa lugubris. This study was aimed to know the success of eye stalk ablation to ripen ovary in spent female. Berried freshwater female crabs (Barytelphusa lugubris) were collected from Sangla Kunchi Pwakal Village Development Committee, Kathmandu Nepal in June, 2008 and were reared in the aquarium till all the eggs hatched into juveniles and left mother's brood pouch. Nine spent females of 50.43- 58.66 mm carapace width were chosen for induced breeding. Three experimental sets were made-each containing three crabs, as A, B and C groups. Group A was kept as controlled without extirpation. Remaining females were first narcotized in 20°C ice-cold water for 15-20 min. and single eyestalk was extirpated with fine scissors in-group B, and both eyestalks in group C. Then ablated eyes stumps were cauterized by hot scalpel and kept in 20c, ice-cold water for two minute. Each group was kept in separate glass aquarium of 85 cm length, 40 cm width and 50 cm height, containing little water with sand, pebbles and 4" PVC pipe as hide out for crabs. The experiments were terminated after two months. This study revealed that all crabs except controlled, moulted within 20 and 40 days, with large dark yellow colored ovaries average 0.16g, dark creamy ovaries average 0.08 g and average 0.04 g in bilaterally, unilaterally ablated and controlled sets respectively. This alteration in induced breeding for rapid ripening of ovaries of spent females resulted as a suitable technique to enhance meat yield in aquaculture of this crab.