An evaluation of stocking density in the cage culture efficiency of Amur sturgeon Acipenser schrenckii

The effects of stocking density (15, 30, 45, and 60 fish m(-2)) on the production economics, growth, food utilization, and body composition of Amur sturgeon reared in cages were investigated. The weight of the fish at the start of trial was 48.7-51.6 g. After 75 days of rearing, the mean weights were 110.3 +/- 11.2, 90.3 +/- 10.2, 79.9 +/- 8.5, 78.7 +/- 7.2 g in the aforementioned densities, respectively. The results show that the growth performances in the various treatments differed significantly (P < 0.05) in terms of final weight and condition factor. The feed conversion rate of 15 fish m(-2) treatment was highest at 1.41, compared with 2.04, 2.08, and 3.13 in other densities. Body protein and fat decreased with the increasing density, while moisture increased (P < 0.05). Final biomasses were 32.3, 49.2, 67.3, and 76.9 kg per cage (cage size: 4 x 5 x 3 m), and benefit-cost ratios were 0.39, 0.22, 0.19, and 0.06, respectively. These results indicate that cage farming of Amur sturgeon stocked at a lower density (15 fish m(-2)) did not achieve higher production, but production economics revealed that it provided the highest benefit-cost ratio.