Age and growth of Salmo trutta fario L. from Yadong River, Tibet

A total of 462 specimens of Salmo trutta fario L. were collected front Yadong River, Tibet, during the period front 1999 to 2002. The population structure and growth characteristics of Salmo trutta fario L. were studied in [lie present paper. Age of 302 individuals was determined with scales. The Von Bertalanffy growth model was fitted to mean lengths of estimated ages of individual fish and estimated growth parameters, female (female) L-t = 709. 44 [1 e(-0.1656(t.-0.0845))] (R-2 = 0.9993, n = 132) and W-t 6017.46[1e (-0.1656(t-0.0845))](2.9724) (R-2 = 0.9845, n = 132); male(male), 797.82[1 - e(-0.14280(t. - 0.0058))] (R-2 = 0.9994, n = 170) and W-t 8566.72 [1 - e(-0.14280 (t - 0.0058))](2.9822) (R-2 = 0.9724, n = 170). Sex ratio of female and male was 1 : 1.29. Growth index was 9.05-14.23 (female) and 10.76-19.22 (male); the mean standard length was 192.60 +/- 69.92 mm (female) and 188.91 +/- 53.18 mm (male). The results showed that the growth rate was significantly different between sexes (p < 0.01 male fish appeared to grow at a faster rate and had longer life-spans than females