tities of nutrients hinder the already meagre growth of algae, and reduce food sources for plankton, leading to less food for the whitefish,” the report states. The drop in catch sizes in Lake Brienz led to discussions in fishing circles, but also in politics. A proposal was made to artificially raise the levels of phosphorous entering the water by making treatment facilities purify the water less thoroughly. The canton, however, refused. Deliberately adding dirty water to the lake was environmentally undesirable. Rising temperatures favour food production Because the drop in fish catches was so massive, Beat Abegglen was forced to abandon his job as a fisherman. Today, he runs his fishery as a hobby and works in another industry as his main job. He sells his fish to customers in the region, who can react flexibly to his catches. However, for the past four years, Abegglen’s catches have been increasing again. Fish no longer weigh around 40 grammes – they now weigh 170-180 grammes again. “At the same time, the whitefish and perch are back,” says Beat Abegglen. Theoretically, Abegglen could now make a living from fishing again. He no longer wants to, though: “I am not giving up the security of a fixed income.” As for why the fish are now doing better, Beat Abegglen has an explanation: the water that flows into Lake Brienz from its tributaries is warmer than it was a few years ago. In Abegglen’s view, this is due to global warming. “Glaciers melting used to result in very cold water flowing into Lake Brienz all year round.” Now, the volume of glaciers has shrunk considerably, and less glacier water is flowing into the Aare and the Lütschine, Lake Brienz’s two main tributaries. The rivers are also transporting less debris into the lake. This means that the lake is less cloudy and sunlight can penetrate deeper into the water. The warmth of the water and the fact that sunlight can now reach great depths has an impact on plankton production in the lake. “So, much more food is being produced for the fish,” says Beat Abegglen. An unstable lake for years Whether Lake Brienz’s ecosystem will remain in such good health is hard to predict. “Lake Brienz has always been in an unstable state,” says Beat Abegglen. This is also recorded in Canton Berne’s research report. In addition, even the new treatment facility cannot eliminate all substances from wastewater. As for how this micro-contamination will affect the lake’s ecosystem in the future, no-one knows. However: “In a couple of years, we will definitely be able to filter these substances out in water treatment facilities,” says treatment facility manager Michael Baumann. This situation has done nothing to dispel the fascination with the largest mountain lake in Switzerland. It continues to be a beloved getaway destination – not least due to its unique colour. This year, commercial shipping on Lake Brienz recorded its highest number of visitors in ten years: 496,000 passengers travelled on the lake by boat. This is around 179,000 more guests than in 2013. In contrast to neighbouring Lake Thun, Lake Brienz is primarily a getaway destination for foreign guests. Nonetheless, the hype is never as great as for other lakes, says Beat Abegglen, who even after more than 30 years’ fishing is still fascinated by Lake Brienz: “In late August, you can always see plenty of shooting stars over the lake. There are so many that it makes you feel awestruck and small.” Iseltwald is a picturesque peninsula rising up out of Lake Brienz. During the summer, historic paddle steamers churn through the often emerald-green water of the mountain lake. Photos: Keystone © Swisstopo Swiss Review / January 2023 / No.1 12 Report
RkJQdWJsaXNoZXIy MjYwNzMx