雅鲁藏布江中游双须叶须鱼群体繁殖力与繁殖策略研究

摘要

The Ptychobarbus dipogon of the Schizothoracinae subfamily,is an endemic economic fish species in Tibet Autonomous Region,China.Due to environment deterioration and invasion of alien species the population size of this species is decreasing;a study is urgently required to determine fecundity and reproductive strategy in order to conserve this natural resource.In this study,to investigate the fecundity and its relationship of body length,weight and age,we captured 1030 individuals in the middle Yarlung Zangbo River during two separate periods,one from February to March in 2013 and the other from February to June in 2014.The results showed that the standard length (SL) of males is concentrated in the 325-400 mm range,and the SL of females is above 375 mm.Sixty five females were at stages ⅣV and V of sexual maturity,with SL 320-500 mm,weight 411.6-1328.0 g.Using the SL 50％ method,the first female sexual maturity age was estimated to be 13.0 years and about 360.90 mm,while the first male maturity age was estimated to be 13.5 years and length 354.53 mm.The distributions of egg sizes,gonadal developmental stages and gonadosomatic indexes show that this species follows a synchronous spawning pattern concentrated in the period February to March,with an absolute fecundity at 3487 eggs,with a fecundity to SL ratio of 7.2 eggs/mm and fecundity to weight of 4.3 eggs/g.The absolute fecundity is positively correlated to the SL and the weight,but not significantly correlated to age.The overall male-female ratio was 1.23 ∶ 1.Suggestions for its conservation have been made based on its low fecundity,late maturity and short breeding period.%双须叶须鱼Ptychobarbus dipogon隶属裂腹鱼亚科,叶须鱼属,是西藏特有经济鱼类,研究通过对其繁殖力和繁殖策略的研究,旨在为双须叶须鱼的科学保护和合理开发提供理论依据.于2013年2月至3月以及2014年2月中旬至6月中旬,在雅鲁藏布江中游区段采集到1030尾双须叶须鱼,雄鱼体长主要集中在325-400 mm,雌鱼体长主要集中在375 mm以上,其中Ⅳ期、V期的雌鱼65尾,体长为320-500 mm,体重为411.6-1328.0 g.采用SL50％的方法,雌鱼初次性成熟体长为360.90 mm,初次性成熟年龄为13.0龄;雄鱼初次性成熟体长为354.53 mm,初次性成熟年龄为13.5龄.从不同月份不同性腺发育期所占比例,不同月份的性体指数变化以及不同月份卵径分布图,可以看出双须叶须鱼属于同步产卵类型,集中在2-4月份.双须叶须鱼平均绝对繁殖力为3487粒,平均相对体长繁殖力为7.2粒/mm,平均相对体重繁殖力为4.3粒/g,绝对繁殖力与体长、体重呈正相关,与年龄无显著相关性.群体性比为1.23∶1.综上所述,双须叶须鱼是繁殖力较低、性成熟较晚和繁殖期较短的鱼类,我们针对其繁殖特性提出了一些保护性建议.