| The silver carp(Hypophthalmichthys molitrix)belongs to Cypriniformes(Cypriniformes),Cyprinidae(Cyprinidae),silver carp(Hypophthalmichthys),is also known as the silver carp.Mainly distributed in China's large and medium-sized south of Yuanjiang River,to the north of Heilongjiang in China.Silver carp is Chinese traditional table fish and is among the world's highest production species.To investigate the daily age,age and growth of silver carp,a total of 234 individuals were collected from Poyang Lake,the Ganjiang River and the Yangtze River during June 2013 to September 2014.The main results are as follows:1,Scales,pectoral fin rays,cleithra and opercular bones of the silver carp showed the typical annulus pattern,which was characterized by alternated wide zones and narrow zones.The marginal increment ratio analysis showed that annuli of pectoral fin rays formed during Februay to May.The IAPE values between two readings by the same interpreter were 5.9%for opercular bones,4.8%for cleithra,2.4%for scales and 1.8%for pectoral fin rays,respectively.The CV values were 9.6%for pectoral fin rays vs.opercular bones,5.9%for pectoral fin rays vs.cleithrum and 3.7%for pectoral fin rays vs.scales,respectively.Pectoral fin rays were the most accurate calcified structure for age estimation of silver carps,followed by scales,cleithra and opercular bones.2,The standard length of silver carp ranged from 120.0 mm to 780.0 mm,with a mean of 368.1 ±154.6 mm.The body weight of silver carps ranged from 31.1 g to 9278.5 g,with a mean of 1561.7 ±1819.9 g.The estimated age range varied from 1 year to 7 years,with a dominant age class of 1 years.The standard length-body weight relationships were described as W = 2.172 × 10-2SL2.974.The von Bertalanffy growth equations were Lt = 96.6(1-e-0.173(t+0.701))and Wt = 17385.3(1-e-0.173(t+0.701)2.97.The growth inflection point is located in the population ti =In b/k + t0 = 5.6,Body length of inflection point Lr= 64.1cm,Inflection point weight Wr= 5139.7g.The age structure and growth performance showed a certain decline trend.The Yangtze River is an important spawning habitat and silver carp,Should be to protect the waters from the fishery management rules and regulations etc.3,The lapilli of the young silver carps showed the typical pattern of alternated translucent and opaque zones,which were respectively equivalent to the accretion and the discontinuous zone,composing a daily growth increment.The estimated daily age range varied from 77 d to 167 d,with a mean of 112.44±14.73 d.The silver carp might lay eggs from March to June according to the estimated daily age.The daily growth equations were BL =-0.809 + 0.155D and W=-167.236 +0.445D for Pengze,BL =-0.067 + 0.154D and W=-141.166 + 0.486D for Hukou and BL = 3.827 +0.122D and W =-334.832 + 0.576D for Xingan,respectively.The growth rates of standard length were 0.155 cm/d for Pengze,0.154 cm/d for Hukou and 0.122 cm/d for Xingan,respectively,while that of body weight were 0.445 g/d for Pengze,0.486 g/d for Hukou and 0.576 g/d for Xingan,respectively.The results show that the silver carp spawning period is using otolith daily age to projections,which can be the basis to calculate the juvenile of silver carp at certain stages of growth model,in order to provide the scientific basis for better protection of silver carp(Hypophthalmichthys molitrix)resources. |
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