摘要
人类引起的环境变化,特别是富营养化和由于气候变化和太阳活动而导致的自然环境条件的波动影响着波罗的海各鱼类和群体的繁殖和生长。在过去几十年间,人类影响的重要性明显增加,在很多情况下掩盖了自然因素。高速的开发降低了一些有价值的鱼的种类,影响了一些种类的支配层次。海洋深层的氧消耗使得某些海洋种类的生存条件日益恶化。随着船舶压舱水而引入的大量非本地种类严重地影响着生态系统和鱼类类群。对于海洋的这些变化的总体影响、残留的和淡水种类可能会产生预想不到的结果。鱼类资源应该根据其自然单元(种群)进行适当的评价和管理。根据全球气候过程的周期性波动,应该着手进行鱼类区系结构和丰度变化的长期预报工作。
Human-induced environmental changes, especially eutrophication, and fluctuations of natural environmental conditions under the changes in climate and solar activity affect the reproduction and growth of various fish species and communities in the Baltic Sea. The importance of human impacts has increased considerably during the last decades, overshadowing in many cases natural factors. High exploitation rates have depressed some valuable fish species and affected the species dominance hierarchy. Oxygen depletion in deeper layers progressively deterio-rates the living conditions of certain marine species. Mass immigration of nonindigenous species with ballast waters can seriously affect ecosystems and fish stocks. The summary effect of these variables upon marine, relict and freshwater species can yield unexpected results. Fish resources should be properly assessed and managed by their natural units (populations). Based on cyclic fluctuations of global climatic processes, composition of long-term forecasts on changes in the structure and abundance of fish fauna should be started.
