Corina Bădălan

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Corina Bădălan, M.G. Băcanu, M. Bărbulescu, D. Oprea, E. Bocioc, L. Oprea, V. Cristea, N. Patriche

The paper is presenting aspects regarding the influence of stocking density on the breeding of siberian sturgeon, in a recirculating aquaculture system (RAS). The experiment took place over 30 days, in four pilot breeding units type aquaria of 300 liters in volume. Two kind of variants were compared, with repetition V1 (B1, B2) and V2 (B3, B4) respectively. The stocking density was of 11 fish/unit in V1 (1,58 kg/ m3) and 22 fish/unit in V2 (3,17 kg/m3). The same feeding quantity of 20 g/kg. metabolic weight (3,7% from total biomass) was used in every unit. The technological indicators that showed up at the end of the experiment revealed the following:
- The mean biomass gain in V1 was of 3,04 kg/m3 compared to 5,62 kg/m3 in V2. This was nearly perfectly correlated with the density variation. The growth rate (GR) variated in a similar way, from 27,33 to 33,03 g/day in V1 and 54,60-57,93 g/day in V2;
- The specific growth rate (SGR), calculated as a mean value on the two repetitions of each variant, was of 3,56 %/day in V1 and 3,39 %/day in V2. This showed a slightly better growth in V1, which is the variant with a lower stocking density;
- The food conversion ratio (FCR), calculated as the mean value of the two repetitions from the two variants, was of 0,91 in V1 and of 0,97 in V2. This indicated a better efficiency for the variant with a lower density.
The parameters of fish breeding showed that doubling the stocking density from 1,58 kg/m3 to 3,17 kg/m3 does not negatively affect the organic load capacity of the system. This experiment showed that it is possible to obtain an increase of fish biomass of over 5,5 kg/month. Acipenser baerii, which is a sturgeon recently introduced in the Romanian farming systems, has a rapid growth rate. This is situating it in the second place, after the beluga, giving it very good perspectives for the Romanian aquaculture sector.

Key words: sturgeon, aquaria, different stocking densities