International Conference on Multidisciplinary Research & Practice Page | 478 Volume I Issue VIII IJRSI ISSN 2321-2705 Effects of Stocking Density on Food Utilization in the Spiny Lobster Panulirus Homarus M Sakthivel, G Jawahar, M Palanikumar P.G.Department of Zoology, Kamaraj College, Tuticorin, Tamilnadu, India Abstract - To study the optimum stocking density, spiny lobster Panulirushomarus was reared at different stocking densities (5, 10, 15, 20 &25 lobster / Glass tanks of 120 lit. capacity). The individuals were fed with natural feed like clam alone. Better feeding rate was found in the lobsters reared with 15 numbers / glass tank than maximum feeding rate (840 J/g live lobster / day) and absorption rate (731J/g live lobster/day) observed in higher density groups having 20 and 25 numbers / glass tank. The absorption efficiency was higher (98%) in the tank reared with 25 lobsters / glass tank. An increase in the stocking density also reduced the conversion rate and net conversion efficiency. Maximum conversion rate and net conversion efficiency of 569 J/g live lobster / day and 46% was recorded in the group having 15 individuals / glass tank and 25 numbers / glass tank showed minimum of 256 J/g live lobster / day and 31% respectively. Hence 15 individuals /glass tank was considered as optimum density for P.homarus. Keywords-Panulirushomarus, Stocking density, Food utilization, Conversion efficiency. I. INTRODUCTION he Indian spiny lobster Panulirushomarus occurs on the coast of Gulf of Mannar from Rameshwaram to Kanyakumari. The spiny lobster, Panulirushomarus and Panulirusornatus are suitable for culture, as they grow to the marketable size reaching an average weight of about 100g in a period of 4 months. Of the two species, P.homarus is quite suitable for growth and availability in Gulf of Mannar regions. Commercially viable hatchery production of spiny lobsters is still thought to be a long way off. Despite more than 30 years of research to develop a suitable compounded feed, it is not at all found out for rearing juvenilespiny lobster (Conklin 1980; Brown et al 1995). The juvenile spiny lobsters fed with mussel diets or clam diets have yielded superior growth and survivalrates compared to formulated diets (Crearet al 2000; Wardet al2003).Severalinvestigations have been conducted to determine optimal stocking densities for Palinurid and homarid lobsters (James et al 2001; Jones et al 2001). The present study was undertaken to assess the effect of stocking density on food utilization parameters of spiny lobster Panulirushomarus. II. MATERIALS AND METHODS The Indian spiny lobsters Panulirushomarus were collected from local merchants at sea shore area of Tuticorin. The individuals were acclimated for fifteen days. After acclimation period the length and weight were noted down. The average weights of the P.homarus were between 70 and 80g. Experiments were conducted on lobsters using a set of glass tanks of 120 litre capacity connected in a flow through system. Aeration by means of two airlines promoted mixing of the water column. In the density trial, the juvenile lobsters were stocked at 5, 10, 15, 20 and 25 individuals in 3 different tanks of same size. All treatments were run in triplicate. For the juveniles, shelters were provided in each tank. Lobsters were fed with live clam only (with shell) twice daily of about 5-10% of their body weight. Excess feed was removed after 3 hours of feeding. Water quality was monitored daily. The water quality parameters like temperature, Salinity and pH were maintained at 28 – 32 o C, 30 – 40ppt and6.5 – 8.5 respectively. In addition to the left feed the moulted shells of lobster was also removed periodically. The weight and length of the lobsters were measured once in every week after introduction into the experimental tank. This was done by using mettler balance and scale. The total duration of the experiments was 60 days. All experimental lobsters were weighed and measured after the completion of the experiment.Calorific content of test lobster, food &faeces were determined by semi-micro bomb calorimeter. 1) Energetics : The scheme of energy balance followed in the present study is based on the IBP formula (PetruseWicz&Mac Fayden 1970) represented as C = P + R + U + F Where „C‟ represents the food energy consumed, „P‟ energy of growth, „R‟ energy expended as total metabolism, „U‟ energy of nitrogenous materials and „F‟ energy of faecal matter. Absorption (A) was estimated by subtracting F from C. Food energy converted into body structure (P = growth) was estimated by calculating the difference between the energy contents at the beginning and at the end of the experiment. The following formulae were used for calculation of the different parameters of energy budget. T