Biochemical studies and energetics of the spiny lobster Panulirus homarus (Linnaeus. 1758)(TH 105)

The spiny lobster landings at Chennai Fisheries Harbour was 5532 kg between February 1999 and January 2000, of which Panulirus homarus contributed 77.6%. The tail muscle of the landed spiny lobsters yielded 312.3 kg, 41.4 kg, 6.4 kg and 8.1 x 106 kj of protein, lipid, carbohydrate and energy respectively. In P. homarus, among the tissues studied (tail muscle, hepatopancreas and exoskeleton), the hepatopancreas had the highest energy (24.6 ± 0.7 kj/g) and lipid contents (31 .6 ± 1.8%). There was no significant difference in the proximate composition and energy contents between the juvenile (body weight: 50-100 g) and maturing (body weight: 150-200 g) P. homarus. No specific trend in the seasonal variation was observed in the proximate composition and energy content. In the experiment on the effect of starvation, the control and bilaterally eyestalk ablated P. homarus survived for 97.0 ± 5.3 and 48.3 ± 4.8 days respectively. The weight loss due to starvation was 37.1% of initial wet weight in the control and 51.6% in the ablated lobsters. The dry hepatosomatic index (HSld) decreased from 4.72% to 1.75% (control) and 1.64% (ablated) in p, homarus at the time of death. All the biochemical components decreased with starvation, with lipid as the major energy source. The protein energy ratio changed from 0.0903 to 0.1342 and 0.1471 in the hepatopancreas of the control and ablated groups respectively. For achieving the maximum growth rate of P. homarus, the effect of four natural food viz., shrimp, squid, clam and mussel on the food utilization parameters were studied. The highest feeding rate (263.5 ± 20.3 jig/d) was observed in the mussel-fed group, but the maximum conversion rate (23.9 ± 1.0 j/g/d excluding moult) was found in the clam-fed group. The intermoult duration ranged from 42.7 ± 1.5 days (clamfed) to 52.3 ± 2.5 days (squid-fed). The food conversion ratio (FCR) ranged between 2.74 ± 0.17 (clam-fed) to 4.08 ± 0.06 (squid-fed). A major share (84.1 to 87.4%) of the consumed energy was partitioned for metabolism and 6.9 to 10.2 % for growth