长江中游宜昌-荆州江段鲢种群年龄结构和生长特征

鲢(Hypophthalmichthys molitrix)是长江重要经济鱼类之一,长江中游是其重要栖息地。为研究其种群现状,2016—2017年对长江宜昌—荆州江段鲢开展了周年调查,共采集鲢样品470尾。结果显示,鲢的年龄范围为1～7龄,体长范围为18.2～93.8 cm,优势年龄组为3～5龄(72.7%),优势体长组为40～70 cm (77.2%);体长和体重关系式为W=4.0413×10~(-5)L~(2.7546)(R~2=0.9297,n=470),为非匀速生长类型;von Bertalanffy生长方程为:L_t=104.71-e~(-0.1603(t+0.89))], W_t=14.811-e~(-0.1603(t+0.89))]~(2.7546);生长参数为φ=3.2448, L_∞=104.7 cm, W_∞=14.81 kg;鲢生长拐点为5.43龄,拐点体长和体重为L_(tp)=66.6827cm,W_(tp)=4.2753kg。本研究表明长江中游鲢种群年龄结构得到了一定恢复,但生长性能出现衰退,建议加强鲢的种群及其栖息地的保护。

Studies on population structure and growth characteristics of Hypophthalmichthys molitrix in the Yichang to Jingzhou section of the middle branch of the Yangtze River

Hypophthalmichthys molitrix is one of the important commercial fish in the Yangtze River, and the section between Yichang and Jingzhou is an important spawning ground and habitat of H. molitrix. In order to study its population status in this area, 470 samples were collected from the annual survey of H. molitrix carried out from 2016 to 2017. The population of H. molitrix has a relatively complex age structure, which contains 7 age classes ranging from 1 to 7. The preponderant age class was comprised of 3-5 year-old individuals, making up 72.7% of the total. Body-length range of the population was 18.2-93.8 cm, mainly between 40.0-70.0 cm (77.2%). The relation between body length and body weight was estimated as W=4.0413×10^-5L^2.7546 (R²=0.9297, n=470), for non-uniform motion pattern; Von Bertalanffy equations and the corresponding growth curves were calculated as L_t=104.71-e^{-0.1603(t+0.89)}], W_t=14.811-e^{-0.1603(t+0.89)}]^2.7546; growth parameters were estimated as L_tp=66.6827 cm, W_TP=4.2753 kg growth inflection was 5.43 years, and inflection point length and inflection point weight were L_tp=66.6827 cm and W_TP=4.2753 kg, respectively. The results showed that the population structure of H. molitrix was complex, but the growth performance had declined. Conservation of the population and habitat of this species should be prioritized.