了解不同种类和大小的鱼类对各种捕捞方式的脆弱性,对于制定最佳的捕捞策略和合理开发鱼类资源至关重要.研究从渔获物组成、捕捞效率和个体大小等方面,对长江中游典型湖泊牛山湖的四种渔具(网簖、刺网、电捕和鸬鹚)的捕捞选择性进行了比较分析.使用相对重要性指数(IRI)评价渔具捕捞对鱼类物种的选择性,同时通过计算渔获物的平均营养水平(MTL)和饵料鱼与凶猛性鱼类的重量比,分析捕捞对鱼类群落营养结构的潜在影响.结果表明,网簖和电捕捕获的鱼类种数多、体长范围广,对鱼类资源的破坏性最大,应当加以限制或废除;鸬鹚是捕获鳜(尤其是高龄鳜)的一种有效方式,但对幼鳜和其他幼鱼也有较大损害,应控制其捕捞强度;刺网主要捕获几种经济鱼类,并可平衡捕食者和饵料鱼之间数量关系,是利用鱼类资源的一种较好方式,关键在于对刺网网目大小和捕捞强度的限制.建议湖泊捕捞应从单一物种转向多物种综合管理,并考虑物种之间的营养生态关系,以更好地保护和可持续利用渔业资源.%Knowledge of the vulnerability of different species and size groups to various types of fishing methods is vital to the development of optimal harvesting strategies and rational exploitation of fish resources.In this study,the selectivity of four types of fishing methods (weir nets,gill nets,electrofishing,and cormorants) used simultaneously in a typical multi-species shallow lake (Lake Niushan,China) within the Yangtze River basin,was compared for catch composition,efficiency,and size selection.Species selectivity was evaluated with the index of relative importance (IRI).Potential fishing effects on the trophic structure of fish community were analyzed by calculating the mean trophic level (MTL) of the catches and the weight ratio between prey and predator fishes.Results indicated that the use of weir nets and electrofishing should be reduced or eliminated,because they were relatively unselective and caught many species,including juvenile individuals.Fishing efforts of cormorants should be restricted due to their high fishing efficiency,especially on piscivorous fishes.Gill nets with appropriate mesh size are likely to be a more sustainable fishing method since they were more selective in capturing larger individuals and could balance the prey-predator relationship.We suggest shifting from single-species approaches toward multi-species management,and taking trophic interactions into account to better manage fishery resources.
展开▼
