Studies On The Biology And Genetic Diversity Of Salmo Trutta Fario L., From Yadong River, Tibet

Salmo trutta fario Linnaeus, an alien species, belongs to Salmo, Salmoninae, Salmonidae, only distributing in Yadong River, Tibet. In this paper, the biology and genetic diversity of Salmo trutta fario L. were studied and its adaptability to the plateau river was discussed. The results indicated as follows:(1)The population age range of wild Salmo trutta fario L. is between 1 and 4. The Von Bertalanffy growth model was fitted to mean lengths of estimated ages of individual fish and estimated growth parameters, female(♀) Lt = 709.44 [ 1 - e - 0.1656 ( t - 0.0845) ] and Wt = 6017.46 [ 1- e - 0.1656 ( t - 0.0845) ]2.9724; male(♂)Lt = 797.82 [ 1 - e - 0.1428 ( t - 0.0058) ] and Wt = 8566.72 [ 1 - e - 0.1428 ( t - 0.0058) ]2.9822. Growth index was 9.05 - 14.23 (♀) and 10.76 - 19.22 (♂); the mean standard length was 192.60±69.92mm (♀) and 188.91±53.18 mm (♂). The results showed growth rate was significantly different between sexes (P < 0.01); male fish appeared to grow at a faster rate and have a longer life-span than females.(2)According to the exterior appearance and the typical characteristics, process of embryo development was divided into 10 periods and described detailedly. The result indicated accumulative temperature ranged between 339.37 and 447.2 (℃·day) from fertilization to hatching, under the condition of average water temperature 4.3℃; a significative liner relation has been observed in number of days of embryos development and accumulative temperature; each stage of early development has different sensitivity to peripheral environment; the stage from somitogenesis to eyed pre-stage was more sensitive than other stages; no significative influences were observed in eggs of different size and hatching rate; the average size of larvae in hatching was 13.09±0.90(mm).(3)Calculating mean monthly changes of gonad-somatic index (GSI) and recording stages of gonad development confirmed that spawning began from the end of October and mainly spawned between November and December. Furthermore, the sexes of Salmo trutta fario L. differed in maturation patterns, i.e. the males matured earlier than the female conspecifics. Some 88% of the females attained the first sexual maturity in their third year and 26.4% of the males attained the first sexual maturity in...