长江天鹅洲故道似鳊年龄、生长和死亡率

Age,growth and mortality ofPseudobrama simoni(Bleeker) in Tian-e-zhou Oxbow of the Yangtze River

基于2011年3月至2012年1月采集的596尾似鳊(Pseudobrama simoni)样本,以鳞片为年龄鉴定材料,对长江天鹅洲故道似鳊年龄与生长进行了分析,并依此估算了种群死亡率。鳞片的年轮特征表现为疏密或者切割型;年轮一年形成一个,在3到5月之间形成。鳞片的可判别能力为97.3%,同一鉴定者两次年龄读数间的吻合率为85.5%。渔获物中雌、雄鱼均由1-5个年龄组组成,优势龄组为1-3龄,占88.38%。雌、雄鱼表观生长指数分别为1.83和1.76。种群自然死亡率为0.47 a-1;捕捞死亡率为0.63 a-1;渔业开发率为0.57。天鹅洲故道似鳊种群处于过度开发状态,需合理管理。

The age, growth and mortality of Pseudobrama simoni were studied using scales of 596 specimens collected in Tian-e-zhou Oxbow from March 2011 to January 2012. It showed that two kinds of annuli were observed in the scales including loose-close and cutting-over pattern. Monthly change in the marginal increment ratio indicated that an annulus formed once in a year, from March to May. The interpretation rate of annual rings reached 97.3% and the agreement between two times of aging by the same reader reached 85.5%. Observed age ranged from 1 to 5 year for both seres, and the 1-3 age classes comprised the majority of the sample, accounting for 88.38% of the total. The growth performances index （￠）for female and male of P. simonii was 1.83 and 1.76. The natural mortality and fishing mortality rate was 0. 47a^-1 and 0.63a^-1, respectively. Exploitation rate was 0. 57. Our study indicated that the population was suffering from over-exploitation, which need to be well managed.