黄山九龙峰保护区尖头的年龄、生长和繁殖
Age, growth and reproduction of the Chinese minnow, Phoxinus oxycephalus in the Jiulongfeng Nature Reserve of the Huangshan Mountain
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摘要: 于2011年5月至2012年4月逐月采集标本, 对黄山九龙峰保护区尖头 (Phoxinus oxycephalus)的年龄、生长和繁殖等生活史特征进行了研究. 尖头 雌、雄鱼性比为0.77:1, 与1:1差异显著. 根据体长频率分布来确定年龄组成,结果显示雌鱼和雄鱼的最大寿命分别为3龄和2龄, 均以1龄和2龄为优势年龄组. 1龄时的体长生长速度最大, 至2龄或3龄逐渐变缓. 雌、雄鱼的初次性成熟年龄均为2龄, 对应体长分别为93.0 mm和76.9 mm. 尖头 繁殖时间为4-7月; 绝对繁殖力较低(174-2151卵粒), 且在2、3年龄组间显著差异, 但相对繁殖力无显著的年龄组间差异. 尖头 的上述生活史特征, 可能体现了对局域环境条件(如营养贫乏、环境动荡及水文周期等)的生态适应性. 尖头 在我国东南部的高海拔地区呈零星分布, 种群数量小, 加之繁殖投入低下, 因此该物种在面临人类干扰和环境变化时极易濒危和灭绝.Abstract: The age, growth and reproduction of Chinese minnow Phoxinus oxycephalus in the Jiulongfeng Nature Reserve of the Huangshan Mountain were examined. A total of 437 specimens were collected monthly from May 2011 to April 2012. The sex ratio was 0.77: 1, significantly differing from the excepted 1: 1 ratio. The population of P. oxycephalus was composed of three age groups for female and two age groups for male, and age 1 and age 2 were the dominant age groups in both sexes. Length growth was fastest in the first year while slowing in the second and third years. Fifty percent of individuals reached sexual maturity at age 1. Results from the monthly changes in gonadosomatic index (GSI) and the oocyte development process showed that the fish spawned from April through July. Absolute fecundity was relatively low, and increased with body size and varied between age classes, whereas no significant difference was observed in relative fecundity in relation to age class. Besides restricted distribution and small population, the relatively low fecundity of P. oxycephalus may suggest that this species is vulnerable to anthropogenic disturbance and environmental changes.