Ide Leuciscus idus (Linnaeus, 1758) belongs to Cyprinidae family and is used in commercial and recreational fishing. Ide is an intermediate host of Opisthorchis felineus . In the control catches (summer 2015, the Lower Irtysh, Uvatsky, Tobolsky and Vagaysky regions of Tyumenskaya Oblast’) there were observed species with lengths 11.9-38.1 cm, with a total weight 45-1085 g. Some species aged 9 years old and even older. The maximum rate of linear growth was registered in ide species younger than 3 years old, at this age annual growth made 5 cm. The annual growth of four-year-old females made 5.4 cm, males - 2.8 cm. Females aged 3+ exceeded males in body weight and length. Species at the age 1+…2+ years old added 204.6% in their mass; at the age 2+…3+ years old - 65.3%, at 3+…4+ years old - 29.4%. Gender and gonad maturity were determined in species older than 2+, but not in all species. Among females aged 2+…4+ there were found species with I and II stage of gonad maturity. Females aged 5+ were spawned-out species having VI-II stage of gonad maturity (48%); female species aged 6+ having IV stage of gonad maturity made 33.4%. Among males in the age groups of 2+ and 3+ there were registered species with I stage (38.5 and 20%, respectively) and II stage (61.5 and 80%, respectively) of maturation only. Fatness degree of studied species ranged from 0 to 5. Species aged 2+ had I stage (24% species); in the aged groups the proportion of such species decreased (5+ years old - 7.8%; 6+ years old - 12.1%; 8+ years old - 5.9%); species aged 2-7 had II stage of fatness; proportion of older species also decreased. Species with III and IV stage of fatness were found more often (III stage was observed in 100% of the fish species at the age of 1+). Proportion of species with V stage was minor, it increased with age. According to the analysis of the study results, nutritive base in the basin is found satisfactory for ide growth and development.
The value of recreational fishing in Sweden – Estimates based on a nationwide survey