Biological features of roach (Rutilus rutilus (L)) growing around trout cage fisheries of the lake Vokhtozero

The research results on the biology of roach (Rutilus rutilus (L)) growing around trout cage fisheries (TCF) located in the waters of the Lake Vokhtozero are presented in the article. It was revealed that the area around trout cage fisheries is inhabited by the roach aged 3+.7+ years. Its length reaches 21,1-25,7 cm, and its weight amounts to 82,9-185,8 g. respectively. In areas located at a certain distance from trout cage fisheries (up to 500 m), the roach was 4+.10+ years old, 22,5-28,8 cm long and 122,8-280,5 g in weight. The weight and the length of the roach feeding in close proximity to trout cages were almost 2 times higher than that of the fish growing at a certain distance from TCF. The gender composition of the roach growing in close proximity to TCF is characterized by the predominance of male species over female species: the sex ratio was 1 : 2. In remote areas, females predominated over males in the ratio 2 : 1. The differences in the size and weight of the roach growing in the areas close to trout cage fisheries and in remote areas are conditioned by the amount of forage reserve found around trout cage fisheries. The sex ratio indicates that females after spawning remain in the coastal (littoral) zone near spawning grounds, and males proceed to areas rich of forage.