安徽无为长江段刀鲚生殖洄游群体年龄结构的变化分析

Analysis on the Change of Reproductive Population Composition of Coilia ectenes in Wuwei Section of Anhui in Yangtze River

为了分析我国名贵鱼类长江刀鲚(Coiliaectenes)数量不断减少的趋势及原因,从而提出资源保护与恢复对策,2006年3～7月在安徽无为长江段,对捕捞刀鲚的渔具、渔法和刀鲚渔获量、种群年龄结构、平均体长、体重进行了野外调查。结果表明,86个网次共捕获刀鲚536尾、34.57kg,最高网次捕获量仅0.85kg;经抽样,对100尾刀鲚进行测定,体长为21.7～42.1cm、体重为20～235g;体长、体重相关式为W=0.0011L3.3312(R2=0.969);种群年龄组成中以2+龄和3+龄个体为主,也能捕获1+和4+龄个体,5+和6+龄个体较少;与1972年相比,捕获量由41.56t降至2～3t。分析认为,刀鲚资源衰退的主要原因是长江水文条件的变化使刀鲚产卵场受到破坏,不断升高的市场价格引起对刀鲚的过度捕捞,而水质污染程度的日趋加重也不利刀鲚的生长繁殖。保护与恢复刀鲚资源的对策应该是建立刀鲚繁殖场保护制度,取缔网目5cm以下的网具或禁捕2～3年。

From March to July, 2006, a survey was conducted to investigate the gears and fishing methods, population structure and the total catch of Coilia ectenes in Wuwei Section of Yangtze River. The results were as follows. The total catch of 86 times fishing was 34.57 kg, 536 individuals, with the highest unitcateh of 0.85 kg. Based on sampling 100 individuals, the body-length ranged from 21.7 em to 42.1 cm, body weight ranged from 20 g to 235 g, the correlation equation between total body length and body weight is W =0. 0011L^3.3312 （R^2 =0. 969, n = 100）. The catch was dominated by individuals of 2^＋ and 3^＋ age-groups. The total catch of Coilia ectenes in Wuwei Section of Yangtze river was estimated to be 2.0 - 3.0 t in 2006. Compared with a total catch of 41.56 t in 1972, the resources of Coilia ectenes decreased sharply. Mainly 3 factors caused this decrease ： 1 ） destruction of the spawning grounds of Coilia ectenes due to the changes of hydrological conditions of Yangtze river ; 2） over-fishing of its reproductive stock due to the ever-increasing price of Coilia ectenes; 3） deteriorated situations unfitable for the growth due to pollution. In order to protect the resources of Coilia ectenes, some measurements were proposed.