雅鲁藏布江拉萨裸裂尻鱼种群资源状况及其渔业管理对策

拉萨裸裂尻鱼为我国特有种,由于过度捕捞和生物入侵,其种群生存受到极大威胁.2008年8月至2009年8月在西藏雅鲁藏布江谢通门至尼木江段共采集拉萨裸裂尻鱼694尾,利用单位补充量模型对其种群资源利用状况及渔业管理对策进行了研究.结果表明:雌性和雄性拉萨裸裂尻鱼年总瞬时死亡率(Z)分别为0.81和0.78年^-1,雌雄种群自然死亡率(M)分别在0.17~0.27和0.21~0.33年^-1,雌雄鱼的当前捕捞死亡率(Fcur)分别在0.54~0.64和0.45~0.57年^-1.拉萨裸裂尻鱼雌鱼种群繁殖潜力比为10.1%~17.9%,全部显著低于下限参考点(F25%),雄鱼种群繁殖潜力比为28.3%~43.6%,仅有22.3%的比例高于目标参考点(F40%).表明在现有的渔业管理政策下,拉萨裸裂尻鱼资源已被过度开发.通过模拟14个不同的渔业管理政策,评估起捕年龄和禁渔期对拉萨裸裂尻鱼的保护效果,结果表明,将其起捕年龄设置为不小于10龄或禁渔期至少设置为2-6月,可实现对其资源的有效养护.

Population resources and fishery management policies of Schizopygopsis younghusbandi in the Yarlung Zangbo River,China.

Schizopygopsis younghusbandi, an endemic species in China, is threatened by overfi-shing and biological invasion. With 694 individuals collected during August 2008 to August 2009 from the Xietongmen to Nimu of Yarlung Zangbo River, Tibet, the population resources and fishery management policies of the fish were studied using per-recruit models. The total instantaneous annual mortality (Z) of S. younghusbandi was 0.81 year^-1 for females and 0.78 year^-1 for males. The range of natural mortality (M) of females and males were 0.17-0.27 year^-1 and 0.21-0.33 year^-1, respectively. The range of current fishing mortality (F_cur) was 0.54-0.64 year^-1 for females and 0.45-0.57 year^-1 for males. The range of spawning potential ratio of S. younghusbandi was 10.1%-17.9% for females, being significantly lower than the threshold reference point (F_25%). That for males was 28.3%-43.6%, with 22.3% of which was higher than the target reference point (F_40%). This result indicated that the stock of S. younghusbandi had been over-exploited under the current fishery management policy. To evaluate the protective effects of capture age and seasonal closure, 14 different fishery management policies were simulated. The results showed that the stock of S. younghusbandi would be effectively conserved by enhancing the capture age to not less than 10 years old or setting the seasonal closure from February to June.