EAA Germany raises alarm: “No healthy water without fish!”

20 years ago, local people sounded the alarm because of the dramatic deterioration in the ecological condition. Since then, the Nister working group (ARGE Nister) has brought stakeholders from administration, recreational fisheries, and science to one table. The causes of the algae growth were investigated under the scientific supervision of the University of Koblenz and strategies for saving the Nister River fish populations were put in place.

Indeed, the main issue concerns the massive development of algae that pollute waters. They invade the bottom of water, which deteriorates the living conditions of fish and shellfish according to Carola Winkelmann, an aquatic ecologist from the University of Koblenz. Hence, the reduction of the fish stocks in the Nister River influences the development of algae and water pollution. For example, certain species of fish, such as the common nase, feed exclusively on algae. They act like a cleaning crew that keeps down the amount of algae. The most important discovery of this project is that fish can improve their habitat for themselves and other groups of species by repelling algae in the water. Fish thus provide ecosystem services of extraordinary value contributing to healthier water bodies.

Water quality is also increasing rapidly due to cormorant hunting. Indeed, as cormorants reduce fish stocks, water quality decreases consequently. A study regarding the influence of cormorants on fish stocks reveals that water quality increases if the number of cormorants decreases. “After targeted protection measures, the condition of the fish population has improved significantly in recent years. The decisive factor was the intensive deterrence of cormorants, as these had significantly reduced the fish population in the Nister and have thus allowed the massive growth of algae. Today the algae are repelled. From the Stein-Wingert bridge, visitors can see large schools of fish swimming their courses on the gravelly ground” – says Manfred Fetthauer, the president of ARGE Nister.

This successful rescue project was awarded the DWA Water Development Award by the Water Industry in March 2023. “We are very happy that we can support this lighthouse project with its important research on the influence of cormorant predation on fish stocks. We very much hope that the display board will help to improve understanding of the problem," says Florian Stein from the German Anglers' Association DAFV.

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EAA Germany and all EAA members around the EU are deeply involved in such restoration projects. For more information, you can find the report of an event organized by the Recreational Fisheries Forum in the European Parliament on the upcoming Nature Restoration Law and the need to secure the continued presence of anglers in protected nature zones.