千岛湖蒙古鲌种群生物学特征及资源量评估

POPULATION BIOLOGICAL CHARACTERISTICS AND STOCK ASSESSMENT OF CULTER MONGOLICUS (BASILEWSKY 1855) IN QIANDAOHU LAKE

  • 摘要: 研究以千岛湖优势鱼食性鱼类蒙古鲌(Culter mongolicus Basilewsky 1855)为研究对象, 于2021年3月至2022年9月逐月收集蒙古鲌样本431尾, 对其年龄、生长、繁殖和死亡等种群生物学特征及种群资源现状进行研究。结果表明, 千岛湖蒙古鲌种群年龄结构完整, 其中2—3龄为优势年龄组, 呈现低龄化现象。种群体长与体重呈幂函数关系, 表现出正异速生长特征。Von Bertalanffy生长方程拟合发现其生长系数(k=0.33)高于其他研究水域, 属于快速生长类型。其生长拐点为3.23龄, 拐点前后对应不同的生长阶段。千岛湖的蒙古鲌种群繁殖时间较长, 种群繁殖力较高, 卵径呈单峰分布, 符合单批次产卵的特征, 整体表现出周期主义繁殖策略。经估算, 千岛湖蒙古鲌种群的初始资源尾数为34.79万尾, 初始资源总量为259.4 吨, 开发率(E)为0.86, 已超过最适利用率, 表明其种群资源处于过度捕捞状态。基于以上研究结果, 研究为千岛湖蒙古鲌资源的保护、恢复和科学利用提供了管理建议。

     

    Abstract: Piscivorous fish species play a crucial role as top predators in the aquatic food webs, contributing significantly to the structure and functioning of ecosystem. Qiandaohu Lake (QDH) has mainly focused on stocking-based aquaculture, particularly with filter-feeding fish such as silver carp and bighead carp, which have become a model for large-scale ecological aquaculture in China. However, little attention has been given to piscivorous fish species in this important ecosystem. Therefore, this study aimed to investigate Culter mongolicus, which is one of the dominant piscivorous fish in QDH. Samples were collected monthly from March 2021 to September 2022, and the population’s biological characteristics such as age, growth, reproduction, mortality, and stock resources were evaluated. The results indicated that the age structure of the C. mongolicus population in QDH was complete, with the 2—3 years age group being the most prevalent and exhibiting slow ageing phenomena. The relationship between standard length and body weight followed a power function indicating positive allometric growth. By fitting the Von Bertalanffy growth equation, this population belonged to the fast-growing type and had a growth coefficient (k=0.33) that was higher than that of other populations in previous research. Different growth stages correlated before and after the inflection point, which occurred at 3.23 years old. The population of C. mongolicus has a long breeding time, high population fecundity, and a unimodal distribution of oocyte diameter, which conforms to the characteristics of a single batch of spawning, and shows a periodic reproductive strategy as a whole. The exploitation of C. mongolicus population rate was evaluated to be 0.86 which showed an over-exploited phenomenon. Finally, we provided suggestions for the fisheries management of piscivores fishes in QDH based on the findings.

     

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