GROWTH DYNAMIC OF THE MAIN MORPHOLOGICAL TRAITS IN A STERLET (ACIPENSER RUTHENUS) POPULATION REARED INTO RECIRCULATING AQUACULTURE SYSTEM, FROM 2 TO 6-MONTHS-OLD PUBLISHEDSorin FURDEAN, Dacian LALESCU, Sandra Antonia MIHAILOV, Adrian GROZEA* None firstname.lastname@example.org
The Danube sturgeons are fishes with high economic value, and their intensive aquaculture shown a wide interest from the Romanian investors. The sterlet (Acipenser ruthenus) is the smallest sturgeon which could be found in the Danube basin, being a fresh water species with many useful characteristics which recommend it as a very good candidate for intensive aquaculture, in recirculating aquaculture systems (RAS). This species can be found at this time in many Romanian farms, which are rearing sturgeons in RAS. The aim of this study is to emphasize the growth dynamic of the main morphological traits and the body indices in a population of sterlet fingerlings, during 4 months, between 2 to 6-month-old, reared into a RAS. The juveniles of sterlet (Acipenser ruthenus) used in this study were obtained using artificial reproduction of the broodfish reared exclusively in RAS in the spring of the year 2016. The juveniles were reared in RAS until the age of 2 months, when the biometrical study started. The RAS used for trials had 3 tanks, with one cubic meter of water each, and the water exchange rate was about once per hour. One hundred and fifty sterlet, 2 months old, were introduced into the 3 tanks of the RAS, 50 fish per tank, in triplication. The main body traits were measured twice per month, from the age of 60 days to the end of 6th month of fish life. The following measurements were carried out: total length (TL), standard length (SL), head length (HL), head width (HW), snout length (SnL), maximum body depth (MBD), mouth width (MW) and body weight (BW). During the experimental period, the fish were fed with sturgeon feed produced by Coppens International (Nederland), with different sizes, from 1.2-1.5 mm to 3 mm according to fish sizes. The amount of feed per day was calculated as a percent of the total fish biomass established at each measurement made at every two weeks. The growth dynamic of the sterlet in the 4 months of study was very fast, with significant differences (p ≥ 0.05) between measurements at every 2 weeks, in almost all cases. The TL of the fish increased from 134.37±11.92 mm to 359.53 mm and the BW greatly increased, from 10.2±2.27 g to 180.53±45.28 g. The other traits registered also good dynamics with certain patens emphasized in the paper. All of these allowed the drafting of growth curves for different traits, very useful for sturgeon farmers but not only.
sturgeons, sterlet, growth dynamic, RAS