Optimization of Stocking Density and Transport Duration for Transportation of Asian Seabass (Lates calcarifer) Fry and Fingerlings using Oxygenated Bags

Background: Asian seabass, Lates calcarifer is a potential finfish for brackishwater aquaculture diversification. Transport of fry and fingerlings size seed without much stress is crucial for ensuring high survival and better economic returns. However, standardized protocols defining the optimum density against seed size and duration is lacking for mass scale seed transportation from the hatcheries to culture sites. This study evaluated optimum densities and transit durations for live transport of seabass fry (1.0-2.0 inch) and fingerlings (3.0 inch) in 30 L polyethylene bags (5 L water, 15.0 ppt salinity, oxygen-filled). Methods: Three trials were conducted: Trial 1 with seabass 1-inch fry (2.6±0.01 cm; 0.30±0.01 g) at 20-100 fry L-1; Trial 2 with seabass 2-inch fry (5.2±0.02 cm; 1.97±0.03 g) at 20-60 fry L-1 and Trial 3 with seabass 3-inch fingerlings (7.5±0.02 cm; 5.03±0.07 g) at 10-30 fish L-1. Survival and water quality were recorded after 6, 12, 18 and 24 h of transportation. Result: Study revealed that seabass 1-inch fry (2.6 cm) survived ( greater than 99.0%) significantly best at densities of 80, 60, 40 and 20 fry L-1 for 6-12, 18 and 24 h transport duration, respectively. Seabass 2-inch fry (5.2 cm) loaded at densities of survived ( greater than 94.3%) at 20 fry/L for 18-24 h, while higher densities (40-60 fry/L) were viable only for shorter durations (≤12 h). Seabass 3-inch fingerlings (7.5 cm) survived the best (97.3±2.3%) at 10 fish L-1 for up to 6 h but survival declined drastically beyond this density and duration, indicating the need for lower densities and shorter transit times. Density, size and duration were interdependent factors affecting survival through changes in dissolved oxygen, pH and ammonia.