“In the Netherlands, salmon was once seen as food for the poor,” says Herman Wanningen, founder of the World Fish Migration Foundation and the Dam Removal Europe movement. “There was a lot of salmon in the 1600s and 1700s, and people didn’t want to eat it every day. Millions of the fish travelled in from the sea and up rivers through the delta on their way to Germany and the Swiss Alps.”
Then came a dramatic change to the rich riverscape with the Delta Works in the mid- 1900s; a series of construction projects in the south-west Netherlands to protect the area of delta surrounding the rivers Rhine, Schelde and Maas. “The Dutch say ‘we’re proud of how we managed the delta. We built dams, sluices, dykes, locks and levees, to make it safe for humans and reduce the risk of flooding’, but the result was that it was not a good place for fish,” explains Wanningen. “That, in turn, had an impact on birds and fish-eating animals, such as eagles and otters. There was far more diversity and abundance of fish and wildlife here 100 years ago.”
What happened in the Netherlands happened on a global scale. Throughout history, humans have attempted to modify and control nature, including water sources for crops, livestock and drinking. But the construction of river barriers accelerated during the Industrial Revolution, to power mills and factories, create reservoirs and aid flood management. Today, an estimated 1.2 million dams, weirs, culverts and other barriers straddle Europe’s rivers – at least 100,000 of which are thought to be obsolete. The UK is thought to have between 50,000-60,000 of these structures, at least 10 per cent of which serve no purpose.
Fears for freshwater fish
この記事は BBC Wildlife の August 2021 版に掲載されています。
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この記事は BBC Wildlife の August 2021 版に掲載されています。
7 日間の Magzter GOLD 無料トライアルを開始して、何千もの厳選されたプレミアム ストーリー、9,000 以上の雑誌や新聞にアクセスしてください。
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