Effect of unilateral eyestalk ablation on ovarian maturation and occurrence of berried females in Macrobrachium rosenbergii (de Man)

Abstract

The efficacy of unilateral eyestalk ablation technique as a means for synchronising ovarian maturation in adult females of giant freshwater prawn Macrobrachium rosenbergii was evaluated in the present study. The experiment was conducted in six out-door cement tanks (7.5x1.75x1.2 m) for a period of six weeks. Experimental group of 18 females was subjected to unilateral eyestalk ablation and was equally distributed in to three tanks. Another group of 18 intact females stocked in three tanks (@ 6 nos. per tank) acted as control group. One adult blue clawed male was released to each of the six tanks for breeding purpose. Prawns were fed twice daily with pellet feed @5% of biomass. Prawns were sampled at weekly intervals to determine the growth, ovarian maturation and health. Results showed a positive effect of unilateral eyestalk ablation on growth and ovarian maturation in M. rosenbergii. Specific growth rate (%) of unilaterally eye-ablated prawns (0.965±0.525) was significantly higher (p<0.05) than that of control prawns (0.869±0.474). Survival rate (%) was higher in control non-ablated prawns (72.22±9.62) than that of ablated prawns (66.66±16.66). Increased number of maturing females in ablated group after six weeks indicated re-maturation after spawning. Unilateral eyestalk ablation has thus accelerated the pace of ovarian maturation however, this was not strong enough to synchronise ovarian maturation in M. rosenbergii.