Study On the Population Dynamics Characteristics and Effective Conservation Action of Coilia Nasus in Changjiang River

Coilia nasus is a kind of migrating fish species, which swims back from the sea to the river for reproduction at the beginning of spring (February to May in China). In this study, its dynamic populations and effective conservation actions from 2003 to 2012 were analyzed. The main results were listed below: (1) The Age-structure analysis showed that the population age-structure is mainly between 2 and 3 years old. (2) Body-weight analysis showed that the body-weight was significant miniaturized from 2003 to 2012 and fluctuated over time. (3) The Body-length analysis showed that the body-length range mainly fluctuated from 24 to 38 cm. There was no difference among the populations between years. (4) The dynamic population of C. nansus was closely related with the migration time and the river’s water temperature. (5) Comparing with historical data, the C. nasus resource had decreased significantly along the years. (6) Genetic analysis showed that a high level of genetic variation and genetic diversity between populations. Further, the effective conservation action including fishing ban, ecological restoration and awaking of people participation have been put forward and carried out. The relevant conservation biology in C. nasus should be more emphasized in the future study.