A study was carried out from November 2010 to October 2011 in Tudakul reservoir, Uzbekistan. A total of 142 silver carps, Hypophthalmichthys molitrix Val., were sampled including 65 females and 77 males. The scale of silver carp is cycloid with straight edges. Annulus on scale of immature silver carp appears in March and of matured fish during the spawning period in the second half of May. The ages, total lengths and weights of the samples ranged between 1 to 5 years, 15 to 105 cm and 35 to 17,500 g, respectively.The relation between the total length (TL) and weight (W) was described by equation W = 0.0065xTL 3.1572 (r=0.99). The relationship between the total length (TL) and the standard length (l) was described by a linear equation: l = 0.8973xTL -1.571 (r = 0.99). The mean estimated total length of 1-yearold silver carp was 25.25 cm; 2-year-old, 49.81 cm; 3-year-old, 68.91 cm; 4-year-old, 89.94 cm; 5-year-old, 94.47 cm. The mean back calculated total length was 28.2 cm at age I; 56.2 cm, II; 71.18 cm, III; 89.56 cm, IV; 98.9 cm, V. R. Lee's phenomenon was not manifested as the fishing company is oriented to the catches of large fish.
Reproductive biology of cultured common carp in Uzbekistan was studied. The ages, total lengths of the samples studied ranged 1-5 years, 5.0 - 87.0 cm in standard length. In spring, 1-year-old fish (8.0-25.0) cm had gonads at stage I; 2-years-old females (18.0 – 33.0 cm) had gonads at stage I (23 %) and II (77 %); 3-years-old females (25.6–47.1 cm) had ovaries at stage II (43 %) and III-IV (57 %); all 4-year-old and 5-year-old females were mature. Females mature when they reached 32 cm in standard length. Absolute fecundity varied 131–1830 thousand eggs, relative fecundity was 190.5–344.0 eggs/g of gutted fish body, real fecundity was 200.0–1300.0 thousand eggs. Average individual ripe egg size varied 1.32–1.52 mm. Positive correlation between maturation, absolute fecundity and growth was determined. For broodstock forming optimization, additional (to body size) fish characteristic should be entered to selection; fish growth could be recommended as such measure. Annual artificial selection of fishes with standard length at different ages (at least SL1 – 13 cm; SL2 - 25 cm; SL3 – 32 cm) would form broodstock which mature at 3-years-old age with real fecundity 800 – 1300 thousand eggs.
The study was carried out in 2014-2018 at the Tudakul reservoir, Uzbekistan. Samples included 278 European bream (Abramis brama), and 83 Amur white bream (Parabramis pekinensis). The age, total length and weight of the fish varied from 1 to 5 years, from 14 to 50 cm, from 30 to 1,405 g for the European bream and from 1 to 6 years, from 24 to 53.5 cm and 105 – 2,138 g for the white Amur bream and European bream, respectively. The relationship between total length (TL) and weight (W) is described by the equation W = 0.005 * TL3.2555 (r = 0.98) for European bream and W = 0.005 * TL3.201 (r = 0.96) for white Amur bream. Recovered average growth rate of European bream: TL1 - 13.5 cm; TL2 - 28.1 cm, TL3 - 37.95 cm, TL4 - 42.6 cm, TL5 - 48.6 cm.The average height of the Amur white bream: TL1 - 12.6 cm, TL2 - 23.3 cm, TL3 - 31.5 cm, TL4 - 37.9 cm, TL5 - 41.7 cm, TL6 - 44.2 cm. Lee’s phenomenon did not appear. All yearling fish were juvenile. In 2-year-old fish of both sexes of both species, the gonads were at stage II. Males and females of both species reached their first maturity at 3-4 years of age, when the total body length of the European bream was 30–32 cm, and the Amur white bream was 34–35 cm.
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