北京地区宽鳍鱲的生长及食性

Growth and diets of Zacco platypus distributed in Beijing

2004-2006年,作者对分布于北京市怀柔水库上游入库河流怀沙河和怀九河宽鳍鱲的生物学进行了研究。结果显示:北京地区宽鳍鱲年龄组成较小,雄鱼最大3龄,雌鱼最大2龄。体长和体重相关关系式为:W=9×10-6L3.1947(r=0.9784),其种群呈异速增长。1龄组雌雄鱼体长和体重无显著差异,2龄组雄鱼体长和体重显著大于雌鱼,可能与雌鱼性成熟后生长速度减慢有关。雄鱼VonBertalanffy生长方程为:Lt=121.56×(1-e-0.3718(t+0.6272)),最大体长121.56mm;Wt=41.16×(1-e-0.3718(t+0.6272))3,最大体重41.16g;生长拐点tr=2.41龄;雌鱼最大为2龄,未能拟合VonBertalanffy生长方程。丰满度和饱食指数均呈周年变化,这可能与水温变化和繁殖期的影响有关。北京地区的宽鳍鱲为植食性,主要摄食硅藻,取食具选择性,且获得的食物量与藻类的多度一定程度上正相关。雌雄性比接近1∶1,1冬龄性成熟;繁殖期5-7月,5月份成熟系数最高。与嘉陵江种群相比,北京种群体长、体重均小于嘉陵江种群;食性上,前人研究认为嘉陵江种群为肉食性,但经我们重新鉴定,嘉陵江种群也为植食性,个别肉食性食物成分可能是随摄食的藻类带入的;在年龄组成、种群增长方式、性比及繁殖特性上,未发现二者有明显差异。基于北京地区宽鳍鱲的生物学特性,结合该地区的环境特点,我们建议通过控制捕捞数量、选择最适捕捞时间、保护原有生境来维持北京地区宽鳍鱲资源的可持续利用。

Zacco platypus, a species widely distributed in the mountainous rivers of East China, is one of the local leading commercial fish in their most naturally distribution area. Total 508 specimens （21.79 mm- 112.82 mm in standard length, SL） collected from the Huaisha and Huaijiu Rivers of the Huairou District in Beijing were used in this study. The characteristics of the age, growth, food and reproduction were studied, and some results were compared to the population living in Jialing River System. Maximum ages were observed as 3 years for males and 2 years for females. The equation of the length-weight relationship is W =9× 10^-6L^3.1947 （ r = 0.9784）, which explains their growth is allometric. The Von Bertalanffy equation of male is Lt=121.56×（1-e^-0.3718（1＋0.6272）, maximum standard length is 121.56 mm, Wt=41.16×（1-e^-0.3718（1＋0.6272）^3, maximum body weight is 41.16 g, growing inflexion is 2.41 years. The Von Bertalanffy equation of females is not be fitted because of their maximum ages are 2 years old. Accordantly annual changes of the fullness and fillness index were observed, which may be mainly attributed to the changes of the temperature in water and idiophase. The food consists mainly of alga and the ingestion owns selection. The sex ratio of Zacco platypus is close to 1 ： 1, and the first maturation age is 1 year. The main spawning season was estimated to be from May to July, and the gonad maturing coefficient was largest in May. The standard length and body weight of the population in Beijing are both smaller than the population in the Jialing River System, which may be due to different living condition and climate between two sites. Previous study on the food of the population in the Jialing River System was carnivorous, but we identified the samples collected from the Jialing River System by ourselves and found a lot of alga existed in their food with some zooplankton. The differences on the age composition, growth mode, sex ratio and spawning characteristics between the two populations were not observed. Bases on the biology characteristics of Zacco platypus in Beijing, we suggests to control the fishing amount, choose comfortable fishing season and protect living condition in order to maintain sustainable use of local Zacco platypus [ Acta Zoologica Sinica 53 （6）： 982-993, 2007].