青草沙水库刀鲚生物学特性初步研究

青草沙水库在合龙和进水过程中引入长江口洄游的刀鲚，目前刀鲚是水库内的优势鱼类，其在水库生态系统中具有重要的地位。根据对2011年5月、7月、10月和12月青草沙水库随机采集的刀鲚样本进行的生物学特性研究，对全长分布、体重分布、全长与鱼体原重和净重的关系、性比、性腺成熟度、性腺指数和摄食等级等进行了分析。研究结果表明：雌雄平均全长分别为25.0 cm、23.4 cm，优势全长组均为20~25 cm；雌雄平均体重为52.0 g和41.0 g，优势体重组均为20~40 g；不分性别刀鲚全长TL与鱼体体重BW及净重DW的关系分别为：WB = 0.0008LT3.3983，WD= 0.0006LT3.4286；不分性别刀鲚的体重BW与净重DW的线性关系为WD = 1.0598WB-0.3425；雌、雄刀鲚的性腺重量与全长、体重之间呈显著正相关性（P＜0.01），雌雄刀鲚的性腺重量随全长、体重的增加而增加；雌雄性比为2.6∶1，经χ2检验不符合1∶1比例；雌雄性腺的发育期多为Ⅱ期，分别占各自总数的69.6%和72.2%，性成熟个体相对较少，4月份和7月份性成熟个体较多，而10月份和12月份成熟个体较少；雌、雄性腺指数具有差异性，雌性性腺指数大于雄性，成熟个体的性腺指数大于未成熟个体，性未成熟的个体性腺指数随着鱼体增大而增大，而性成熟个体的性腺指数却随着鱼体增大而减小；刀鲚胃含物中以虾为最多，摄食等级以0~1级为主，占61.11%。

Biological characteristics of Coilia ectenes in Qingcaosha reservoir

Coilia ectenes is an abundant species in Qingcaosha reservoir and plays an important ecosystem role. Seasonal surveys were conducted in 2011 to sample the specimens of Coilia ectenes for studying their biological property. Statistical approaches were used in data analysis to describe the biological characteristics of Coilia ectenesin Qingcaosha reservoir. The dominant total length （TL） of the samples of both females and males was 20-25 cm with the means of 25 cm and 23.4 cm, respectively. And also, the dominant round weight of different sex samples was same with the range of 20-40 g. The relationships between TL and BW （body weight）, TL and DW （dressed weight） of all samples could be described as WB = 0.0008LT3.3983 andWD= 0.0006LT3.4286. Pearson correlation analysis showed a positive correlation existing in both gonad weight versus total length and gonad weight versus round weight for different sex samples. Moreover, it showed a trend that the gonad weight of Coilia ectenes increased with both their total length and round weight. The sex ratio of the samples of C.ectenes was 2.6∶1 which was not in accord with 1∶1. The gonad analysis indicated that more mature individuals were found in May and July, and the dominant maturity samples were mainly at stageⅡwhich accounted for 69.6% for femals and 72.2% for males; Furthermore, the mature individuals ’gonad somatic index （GSI） was obviously higher than immature individuals’ and the immature individuals’ GSI tended to increase with total length and conversely for the mature individuals’. The main prey of Coilia ectenes was shrimp and the feeding intensity was mostly in the class 0 and 1 which accounted for 61.11% of the total in the samples.