Nahrung aus dem Meer

Background and Scope

There is a multitude of uses in the seas worldwide: fishing, shipping, tourism, exploitation of oil and gas, sea-bed mining, waste disposal, etc. They all compete for space and resources. Each of them has its specific impact on marine ecosystems. Furthermore, they interact with each other and with the marine environment. Fisheries are the most deleterious interactions of man with marine ecosystems by withdrawing a major part of the annual production of large fish, molluscs and crustacea. Many marine habitats are destroyed by fishing, particularly by heavy bottom trawling.

Basics of Fisheries

The production of a fish stock can be increased by removing the old fish. Fishing is sustainable as long as it is restricted to the removal of the surplus production. Subventions and market forces are opposed the rational way of effort reduction aiming at the recovery of overexploited stocks. Fishing has collateral effects on target species. Heavy selective fishing of large, slow-growing predatory fish will favour small, fast-growing species of a lower level in the trophic pyramid. Fishing in marine ecosystems is a complex process in which biological and economic factors interact. At different scales of space and time they are superimposed by changes in the oceanic environment. Climatic variations and global warming of the Ocean differ in their effects from region to region, and they affect distribution, composition and fishing yield of the various exploited fish stocks. Politics has a major impact on the development of fisheries; historical examples are the collapse of the Eastern Bloc with its big distant water fishing fleets, or the introduction of the 200 nm Economic Zones, putting most fish stocks under national jurisdiction.

Discussion

Fishery science is still striving to understand the variability of year-class strength in fish stocks. In the foreground of modern research, however, are the interactions in multi-species communities in relation to changes in the abiotic and biotic environment and to different kinds of management. We have no possibility to study the complex interactions in marine fish communities by controlled experiments. The only information we have are records on landings and fishing efforts. They provide the basis for sophisticated mathematical models. Ecosystem modelling is a relatively young field in marine ecology. In Europe and North America fishery science is more than hundred years old. It is not possible, however, to apply the methods and models of, e.g., North Sea research to low latitude ecosystems and fisheries.

Conclusions

The sustainable use and protection of the marine living resources and biodiversity are global challenges. Each Large Marine Ecosystem calls for specific solutions in terms of research and management. Problems have to be tackled not only by computer models and remote sensing, but also by field research in all parts of the world. The further development of marine and fisheries research in developing countries is a matter of north-south-partnerships with high win-win spin-offs. Over the past decades some excellent groups of marine scientists from several tropical countries have been established who are very open for partnership projects in the true sense. They offer great opportunities to jointly study the richness of marine fauna, flora, and ecosystems in tropical and subtropical shelf seas and up-welling regions.     

Naturwissenschaften Aktuell

Naturwissenschaften Aktuell     

Naturwissenschaften aktuell

Naturwissenschaften aktuell     

Why a Global International Waters Assessment (GIWA)?

Why GIWA? Six years ago several people had their doubts as to whether a Global International Waters Assessment would be worth the money and effort. Nowadays, it is no longer necessary to justify the creation of GIWA. On the contrary, we will show how important it was that the Global Environmental Facility (GEF) and UNEP, constituted GIWA. Countless water-related assessments focus on specific regions and/or specific issues. But GIWA is unique in its global and holistic policy-oriented approach applying a common methodology to address the major problems in all parts of the global hydrosphere. One major achievement of GIWA will be the GIWA publications which provide advice to GEF and other decision-making organizations. Further assets include the network of regional focal points and teams. GIWA encompasses marine, surface freshwater, and groundwater systems, following the flow of water from the sources in the mountains through the rivers and estuaries into the coastal waters and the shelf seas. GIWA studies the physical, chemical and biological properties of those waterbodies and living resources in relation to the human activities, combining ecological and socioeconomic considerations.     

Biologische Probleme der Befischung mariner Ökosysteme

New political, economical, and technical developments have changed the character of world fisheries. The exploitation of relatively small marine organisms, mainly pelagic fish, as a source of protein and the large distant-water fishing fleets of some countries operating worldwide make it possible to change marine ecosystems and particularly the upper parts of the food chain rapidly and drastically. The paper discusses recent changes in North Sea fish stocks and the ecological effects of antarctic whaling.

     

为什么要开展全球国际水域评估(GIWA)

为什么要开展全球国际水域评估(GIWA)?就在6年前还有人怀疑是否值得花费财力和物力开展全球国际水域评估.现在已经没有必要证明创建这个项目的正确性.相反的是,我们可以证明全球环境基金(GEF)和联合国环境规划署(UNEP)开展这项工作很重要.无数与水相关的评估只是针对一些特定的区域或特殊的问题,而GWA是全球独一无二的项目,它采用了一种使用通用的方法的、全球的和统一的政策途径以识别全球水圈任何部分的主要问题.GIWA的一项主要成果是为全球环境基金和其他决策组织提供公开的全球水域评估报告.此外,它还创建了一个包括区域重点和工作团队的网络.GIWA覆盖海洋、地表水以及地下水系统,对山区的源头到河流、入海水流以至近海水域开展评估,综合考虑生态和社会经济状况,研究这些与人类活动相关的水体的物理、化学和生物特性及生物资源.