Study On The Age,growth And Population Dynamics Of Paramisgurnus Dabryanus,an Alien Species In Chabalang Wetland

Paramisgurnus dabryanus belongs to Cypriniformes,Cobitidae.Based on previous data and the results of this survey,we can draw the conclusion that the alien P.dabryanus could survive in the Qinghai-Tibet Plateau water environment,its biology and population dynamics have not been reported before.In this study,we studied the invasion pathway,age structure,growth characteristics and population dynamics of the P.dabryanus in Chabalang wetland,and compared the age structure of the species with the original region to reveal its growth characteristics in the plateau wetland,provided basic information to control the alien Fish.The main results are as follows:The survey of fishery resources conducted in the Chabalang Wetland and the Lhasa River Quay from early April to mid-May 2017 showed that the composition of exotic fish in the Lhasa River is consistent with that in the wetland,and there are 7 exotic fishes that are respectively,Pseudorasbora parva,Hypseleotris swinhonis,Abbottina rivularis,Carassiusauratus,P.dabryanus,Misgurnus anguillicaudatus,Silurus asotus.According to the results of this survey and previous related data analysis,we could infer that the P.dabryanus in the wetland came from the Lhasa River.Then we accomplished the research about the scales and otoliths of the major scales as the P.dabryanus,the study of 298 large scales of the P.dabryanus showed that the scales and otoliths could be used as the age-identifying materials,while the otolith was more suitable.The results showed that The P.dabryanus has established a natural population in Chabalang wetland,and the body length ranged from 5.13 to 16.92 cm,the body weight ranged from 1.22 to 49.89 g.There were 7 groups of age ranging from 2 to8 years old,while the dominant age group ranged from 4 to 6 years old.Correlation analysis showed that there was no significant difference between male and female body lengths and body weights.The relational expression between body weight and body length was W=0.010L^2.917,displaying uniform growth model.The logistic growth equation of length and weight were L_t=12.740/(1+e^0.803-0.530t),W_t=16.740/(1+e^0.803-0.530t)^2.917,respectively.The inflection point age of P.dabryanus used in this study was 3.5 years old,while the corresponding body length and body mass were 9.44cm and 6.99 g respectively.Compared with low-altitude areas,the age-structure of P.dabryanus on the Chabalang Wetland shows an increase in old age.It may be due to local fishing efforts that are small or absent,which allows them to naturally grow to older ages.And to express their growth characteristics,for individuals to reduce,growth indicators decline,these changes may be caused by the alien species in order to better adapt to the plateau low-temperature water environment.The natural mortality?M?is 0.768 per year,the ecological type of P.dabryanus is the r selection.And the population dynamics of the species are analyzed through its natural death coefficient?M?,ecological type,and life table,the results indicate that the abundance of the alien P.dabryanus is continuously increasing in population abundance in Chabalang wetland.