At the end of the experiment, specific growth rate (SGR) calculated in V1 variant was 1.58% g day-1, in V2-1.56% g day-1, V3-1.40% g day-1 and V4-1.55% g day-1. The fish were fed with commercial STECO PRE GROWER-14–extruded pellets for sturgeons with a protein content of 50% and a fat content of 14%, the feeding intensity being 1.6% from body weight (BW) per day. Researches were conducted between October 20th, 2015 and November 18th, 2015, in the recirculating system of the Aquaculture, Environmental Science and Cadastre Department, University of Galati. A number of 300 hybrid bester with an average weight of 76.6±5.36 g were randomly divided into four rearing units in order to create different stocking densities: V1-14.95 kg m-3 V2-10.74 kg m-3 V3-4.56 kg m-3 and V4-3.19 kg m-3.

The aim of this paper was to evaluate the influence of different stocking densities on growth performance of the hybrid bester sturgeons (Huso huso ♂ x Acipenser ruthenus ♀), reared in a recirculating aquaculture system.

mento and clupeids/small-sized fish species in the lower Cross River and tropical environments. This finding serves as baseline for management of O. The fish was yet to complete 50-55% of growth as at the time of capture at Lc, L25 and L75 compared to L, hence, Lopt = 10.1 cm TL, provides least impact on the stock. The length-at-first capture Lc = 5.64 cm TL at age 1.7 yr. Results indicate the fishery is lightly exploited with current exploitation ratio, Ecur = 0.38 < Eopt = 0.5 rate of exploitation, μ = 0.3481 year-1 < Ecur, 35% of the available stock being fished annually corroborated by Z/K ratio (< 2) and M/K = 2.08, indicating environmental stability. The computed total mortality, Z = 2.54 year-1, natural mortality, M = 1.58 year-1 and fishing mortality, F was 0.96 year-1. The estimated growth performance index, φ′ = 2.444 based on length and φ = 0.6833, using weight. The von Bertalanffy exponential growth parameters were estimated as: asymptotic length (L∞) = 13.7 cm TL, growth curvature (K) = 1.48 year-1 and length-at-age zero years, t0 =-0.13 Lo = 2.40 cm TL. Three year classes with mean lengths of 7.4 cm, 11.55 cm and 13.3 cm TL, respectively, were identified. The length-weight relationship of the species indicated isometric growth (b = 3.005 r = 0.9623). The population dynamics of Odaxothrissa mento in the lower Cross River, southeast Nigeria, were obtained from a six month length composition data (4.25-14.75 cm TL mean = 5.91 cm ± 1.02 and 0.71-7.36 g 1.62 g ± 1.24 n = 1012).

Isometric drawing pipe line