Species Identification And Biological Characteristics Of Coilia Brachynathus In The Poyang Lake

There are four species of anchovy in China,such as Coilia grayi,Coilia mystus, Coilia ectens and Coilia brachynathus.The anchovy is small-sized fish.In the northern part of the Poyang Lake,anchovy is the most important fishing objects and its daily catch of each boat is up to 2.5 tons in the peak period.However,the study on species identification and biolodical characteristics of anchovy in Poyang Lake is scanty.So it is necessary to research the anchovy in Poyang Lake.In this paper,the species of anchovy in Poyang Lake is identified through the characteristics of the external morphology and internal structure.Meanwhile,the age,growth,reproductive biology,population composition,and relationship between its resource and environmental factors are indicated.The main results are summarized as follows:1.The anchovy in Poyang Lake is determined as Coilia brachynathus through the clustering analysis of the life habit and main characters with four species of anchovy in China.2.The annual rings on the squama can be divided into widely and narrows spaces type and shatter type.There is a linear correlation between the standard length and scale radius of Coilia brachynathus.And the relationship between its standard length and body weight can be expressed with power function.3.The population structure of Coilia brachynathus is simple.The results show that the population includes the age groups of 0 and 1 year,and they account for 94.97%and 5.03%of the total number,respectively.There are many of small-sized individuals in its catch composition.4.The condition factors of Coilia brachynathus changed with season.The influence of the condition factors is identical with feeding and spawning.Among spawning period,the condition factors are declining.But after spawning period,they are rising because of feeding.5.Coilia brachynathus is the onetime spawning fish.Its spawning period is from April to July.And the breeding events are May to July.6.The mean absolute fecundity of Coilia brachynathus is 14049.00±7745.00 egg,and the mean relative fecundity is 848.00±205.00 egg·g^-1 and 768.00±249.00 egg·cm^-1.The absolute fecundity increases with the increase of body length,body weight and somatic body weight,while there is no significant relationship between relative fecundity and body length,body weight or somatic weight.7.The annual change of the mean catch of Coilia brachynathus by fixed net is significant.There is a positive correlation between the mean catch of Coilia brachynathus by fixed net and the water level,water temperature.The fishing season of Coilia brachynathus is September to Octember in the Hukou waters of Poyang Lake.