An evaluation of the intertidal oligochaete Pontodrilus bermudensis beddard as dietary supplement for stimulation of reproduction in Penaeus semisulcatus de Haan (TH 102)

Abstract

The major impediment to the culture of penaeid shrimp in captivity is the inability to obtain ovarian maturation and spawning. The present thesis evaluates the reproductive performance of unablated Penaeus semisu/catus (green tiger shrimp), fed the intertidal oligochaete Pontodrilus bermudensis as a dietary supplement. The reproductive performance of the test group of P. semisulcatus fed P. bermudensis as dietary supplement was compared to that of the control group, fed squid and clam alone. Significant improvement was observed in the reproductive performance of test group compared to that of the control group. Maximum maturation response was observed when the worm component formed about 9% of total feed . The biochemical composition and fatty acid profile of P. bermudensis was analysed. Among the three growth stages comprising the population of P. bermudensis, the nonclitellates were found to have the most suitable biochemical composition for feeding the broodstock. The fatty acid profile of P. bermudensis revealed a preponderance of n6 fatty acids especially C20:4 n6, suggesting a possible role of prostaglandins in shrimp maturation and spawning. Experiments were conducted to develop a viable long-term method to culture the oligochaete in land based culture units. Of the three culture systems tried, P. bermudensis was found to grow well in wooden boxes with seashore sand as media with cowdung and seaweed or cow dung and leaf litter as organic amendments. A multi unit vermiculture system with periodic harvesting and loading of organic matter is proposed as part of shrimp maturation systems with minimal investment to facilitate continuous supply of worms.