Characteristics of firstly spawning brood rainbow trout Oncorhynchus mykiss (Walbaum) reared in the conditions of the industrial fish farm Sloboda-Banyliv

Purpose. To analyze the results of rearing and to provide fish culture-biological characteristics of firstly spawning brood rainbow trout based on their offspring reared using industrial technology in the conditions of the trout farm “Sloboda-Banyliv”. Methodology. Rearing was performed in tanks of the trout farm “Sloboda-Banyliv”. The material for the study were age-2 rainbow trout produced from eggs of an autumn-spawning form of rainbow trout. Rearing was performed in a 216 m2 tank with a stocking density of 37 fish/m2 according to generally accepted trout culture methods. Evaluation of the brood stock was performed was performed using productive and reproductive features. Growing of larvae was done for 45 days in plastic trays with a stocking density of 10 thousand fish/m2. Statistical processing of the material was done in Microsoft Office Excel (2003). Analysis of values for performed in the system of absolute values. The criteria for analysis were their mean values and standard error (M±m), deviation (σ), coefficient of variation (Cv). Fish were fed with the artificial feed “Biomar”. Findings. The works on the creation of rainbow trout brood stock showed that brood fish reared in the conditions of the industrial fish farm “Sloboda-Banyliv”, despite instable rearing conditions, were characterized by a moderate growth rate and high values of productive and reproductive features. E.g., mean body weight of age-2 females was 720.9 g with a fecundity of 2.3 thousand. Mean weight of produced eggs was 101.3 g. Fertilization rate was almost the same in all studied females and varied within 84.9–92.7 %. Mean weight of 45 day larvae was 974.5 mg. Survival rate of fingerlings was on average 47.7% with a variation from 42.1% to 52.3%. Originality. A study on the creation of rainbow trout brood stocks in a tank fish farm with instable conditions of rearing with the use of an analysis of productive and reproductive features was performed in Ukraine for the first time. The studied feature such as egg diameter can be used as a parameter of the breeding value of females both broadly and for the creation of selective-breeding stocks, because it is a parameter of maturation rate, i.e. the main feature for early maturated form. Originality. The results of the performed work can allow selecting and creating a full brood stock at fish farms wit instable rearing conditions, which are characterized by high values of productive and reproductive features of firstly spawning age-2 fish