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Abstract
The effect of stocking density on growth, survival and production of barramundi fingerlings nursed in inpond floating raceways was examined in two-phase experiments. Fish were nursed in model floating raceways (60 L/raceway) with a water exchange rate of circa 7 times/hour. In phase 1 which lasted for 28 days four stocking densities (5, 10, 15, 20 fish/L) were evaluated using small fingerlings of barramundi (18.07 ± 1.60 mm total body length). Results showed that stocking density did not affect growth and survival of these small fingerlings (P > 0.05). Cannibalism was the main cause of mortality in this phase and was highest between day 8 to day 15. However, size variation and feed conversion ratio were affected by stocking density. Size variation was highest at density of 20 fish/L (CVW: 49.8%) and similar between the 5, 10, 15 fish/L (33.6 – 42.5%) treatments. FCR of fish nursed at densities of 10, 15 fish/L (0.73 and 0.72, respectively) were lower than that of fish nursed at densities of 5 and 20 fish/L (1.04 and 0.96, respectively) (P < 0.05). In phase 2 fingerlings of barramundi with TL 61.2 ± 5.6 mm (3.2 ± 0.8 g) were nursed for 24 days at densities of 4, 6 and 8 inds/L. Specific growth rate (SGR) was not affected by stocking density (P > 0.05). However, final body weight (BW) and absolute growth rate (AGR) of fish nursed at density of 8 inds/L (9.5 g and 0.27 g/day) was lower than those nursed at densities of 4 and 6 inds/L (10.2 – 10.4 g and 0.30 g/day) (P < 0.05). Survival rate ranged from 94.8 – 97.7% and was not affected by stocking density. FCR of fish nursed at densities of 6 and 8 inds/L (0.99 and 0.98, respectively) was lower than those nursed at density of 4 inds/L (1.18). Production increased with higher stocking densities and was 40.2, 57.0 and 69.2 kg/m3 for the three treatments.
Keywords: floating raceway, stocking density, growth, survival, fingerling, barramundi, Lates calcarifer