| Tor sinensis belongs to Cypriniformes, Cyprinidae, and Barbinae. From April2009to May2012,254specimens were collected from Nanna River and Little black river to the lower reaches of the Lancang River through taking the initiative to fishing and passive collection. This paper deals with the biological characteristics and the population dynamics of T. sinensis. The main results are as follows.1. It is fragile to the otolith of T. sinensis during the procedure of polishing. Compared to opercular and vertebra, it is complicated to deal with the otolith. There are annulus on operculum bone, otolith and vertebra, but annuluses on otolith are more obvious, clear and precise than operculum bone. Furthermore, although vertebra has distinct annulus, it is unable to estimate the onset age. So, otolith was the best ageing material for T. sinensis.2. The age composition of T. sinensis was from1to7and9, and the individuals of the preponderant age groups were2years old, accounting for30.12%and age groups from2to6accounting87.95%. The body length average of T. sinensis was171.58mm, preponderant groups was100mm-200mm, accounting35.00%of the individuals and the body weight average was257.0g, preponderant group was individuals less than100.0g, accounting25.94%.3. The relationship of body length and body weight for T. sinensis was W=0.0000179529L3.0228609956(R2=0.98368, n=254), while it was L=L=-0.0001R2+0.4013R-21.261(r2=0.9898, n=254) for the body length and radius of otolith. The Von Bertalanffy growth equation of body length were Lt=521.8652(1-e-0.1658(t+0.3753)), and body weight growth equation were Wt=2943.9855((1-e-0.1658(t+0.3753))30229. the incremental length, weight and instantaneous rate of growth were L∞=521.8652mm, W∞=2943.9855g, and k=0.1658/year, respectively. The inflection point for the growth were7.05years, corresponding body length and weight was Lt=369.43mm and Wt=1036.14g.4. T. sinensis was hypognathous. the length of intestines was2.4～3.6times to the body and the relationship was IL=3.5288×BL-88.018,(R2=0.9431, n=20). T. sinensis was an omnivorous fish species which feed on the algae, aquatic plants, protozoa, rotifers, annelid, mollusks, and arthropods and so on.5. The development of both ovary and spermary of T. sinensis was divided into six stages. There are five phases’ cells in the ovary and five kinds of germ cells in spermary. At the last second phase and the early third phase oocyte, some yolk mucleus can be found at the cytoplasm and exocytosis of plasmosome appears. It may be relevant to the forming the yolk granules arounding the nucleus. The spermary of T. sinensis was lobular type.6. The life history pattern of T. sinensis tended to be r selection. The natural mortality coefficient M was0.3094, total mortality coefficient Z was0.5787, fishing mortality coefficient F was0.2693, and exploitation rate E was0.4654. Using Length based Cohort Analysis (LCA) and B-H model to estimate the population size of T. sinensis, it can be concluded that the exploitation rate was overdeveloped at present. To protect T. sinensis resource, we recommend decreasing the fishing intensity, and regulating specification for fishing. What’s more, the first capture age should be put off to4years old. |
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