Stocking density effects on growth, blood chemistry, stress indicators, muscle composition and the economics for production of grow-out Indian pompano (Trachinotus mookalee) in floating marine cages

Megarajan, Sekhar and Ranjan, Ritesh and Ghosh, Shubhadeep and Xavier, Biji and Shiva, Ponnaganti and Sadhu, Narasimhulu and Ignatius, Boby and Raju, S S and Gopalakrishnan, A (2025) Stocking density effects on growth, blood chemistry, stress indicators, muscle composition and the economics for production of grow-out Indian pompano (Trachinotus mookalee) in floating marine cages. Regional Studies in Marine Science, 92. pp. 1-13. ISSN 2352-4855

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Abstract

A 300-day grow-out experiment was performed in circular floating marine cages of 100 m3 volume to assess the effect of different stocking densities on the growth, stress physiology, muscle nutritional composition, and economic profitability of Indian pompano, Trachinotus mookalee. The hatchery-produced fingerlings (>20.0 g) were stocked in cages in triplicate at four different stocking densities, 15 (SD-1), 20 (SD-2), 25 (SD-3), and 30 (SD-4) numbers/m3. The fish were fed a commercial floating pellet feed (40 % crude protein and 10 % crude lipid) at a frequency of 4–3 times daily and a rate of 5.0–1.5 % of body weight. Growth monitoring was at 30-day intervals; serum biochemical assay was performed on the 30th, 150th, and 270th days of culture (DOC); and muscle biochemical composition was carried out at 270 DOC. Mean final weight and absolute growth rate were significantly higher in SD-1 (848.0 ± 25.57 g and 2.75 ± 0.08 g/day) and low in SD-4 (748.33 ± 19.72 g and 2.41 ± 0.07 g/day). Survival was significantly lower in SD-4 (87.87 ± 0.97 %), due to mortality caused by parasitic infestation. Total harvested biomass was significantly higher in SD-4 (1999 ± 72.77 kg/cage) and SD-3 (1861 ± 27.72 kg/cage), in comparison to SD-1 (1216 ± 49.05 kg/cage). The concentrations of stress indicators (serum glucose, cortisol, and heat shock protein-70) were significantly higher in SD-4 on 270 DOC; and for all stocking densities, values increased with progression of culture duration. Significantly lower lipid and low energy-providing fatty acid (palmitic) were observed in fish muscles at SD-4 (3.4 ± 0.26 % and 16.95 ± 1.17 %) than in SD-1 (4.41 ± 0.23 % and 29.42 ± 0.85 %), indicating that the fish utilized higher energy at higher stocking density. A higher net operating income ($2887.71) and annual rate of return to capital (50.36 %) in SD-3 indicated greater economic profitability. For other stocking densities, net operating income and annual rate of return to capital varied from $1795.72 to $2695.27 and 24.86–45.87 %. Considering all production traits, the present study recommends sea cage culture of Indian pompano at a density of 25 nos./m3, with a maximum carrying capacity of up to 18.61 kg/m3. This study forms the first comprehensive report on sea cage farming of Indian pompano for sustainable mariculture operations.

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