Ontogenesis Evolution of Body Size Indices in Rainbow Trout (Oncorhynchus Mykiss) Reared in Different Growth Systems

Experiments were conducted throughout 2009 and 2010. At the beginning of experiments, both in 2009 and in 2010, were formed two groups (M-control group; E-experimental group), each group far 600 rainbow trout (Oncorhynchus mykiss). Control group M has been exploited in the Fiad trout farm, Bistriţa-Năsăud County, and the experimental group E was operated in a recirculating system arranged in Cluj-Napoca. Experiments were conducted over 210 days, both in 2009 and in 2010. Initial body weight of the specimens was 22.70±0.40 g – group M, and 22.68±0.39 – group E, in 2009. In the second experimental series (2010), the initial body weight of the rainbow trout specimens was 22.69±0.28 g – group M, respectively 22.56±0.31 g – group E. To determine the body size indices, we made measurements and weighings in all age groups exploited. Based on measurements, we calculated: K – Fulton condition factor; Ig – thickness factor; Ip – profile indices; Ica – quality indices; Ic1-meat index expressed as percentage of head lenght from standard lenght of fish; Ic2- meat index expressed as percentage of caudal peduncle lenght from standard lenght of fish. Analysing the value of body size indices in rainbow trout in the two test series (2009 and 2010) we found that they are directly proportional to fish weight, but are significantly influenced by the environmeltal conditions and the feeding rate. The mean values of body size indices (K, Ip, Ig, Ica, Ic1 and Ic2) in rainbow trout from the two experimental series, fall within the range cited in the special literature.