Survival, growth and food conversion efficiency of <i>Panulirus ornatus</i> following eyestalk ablation

Abstract

The viability of eyestalk ablation as a means to enhance the growth of juvenile spiny lobsters in commercial growout cultures was investigated in a 4-month experiment. Three replicate groups of small-sized (86.3–94.4 g total weight; 44.1–46.6 mm carapace length (CL)) Panulirus ornatus were subjected to three experimental treatments: unablated/control, unilateral and bilateral eyestalk ablation. Only animals which were initially at the intermolt stage were used in the experiments. The average food conversion efficiency (12–17%) and monthly growth rates of bilaterally ablated lobsters, based on both total weight (42.0–64.0 g) and carapace length (6.7–7.0 mm CL) increments, were significantly higher than lobsters in the two other treatments during the first 2 months of the experiment but declined thereafter. At the end of the experiment, only 6% of the bilaterally ablated lobsters (n = 48) survived compared with 73% and 75% for unilaterally ablated and unablated lobsters, respectively. The extreme sensitivity of bilaterally ablated lobsters to water quality and diet renders bilateral ablation impractical for commercial growout culture. The high survivorship and generally higher growth rates of unilaterally ablated lobsters compared with unablated lobsters resulted in the highest gross yield among the three treatments. The results indicate that unilateral ablation may be a viable option to consider in accelerating the growth of small juvenile P. ornatus to a marketable size of 200–300 g.