'It's now too late': How invasive species have altered Lake Constance

Fishermen in Lake Constance, Europe's third-largest lake which borders Germany, Switzerland, and Austria, are becoming increasingly concerned that the dwindling populations of edible fish are threatening their livelihoods.

Researchers report that local species of fish are being deprived of food because other invasive species, such as three-spined sticklebacks, quagga mussels, killer shrimps, and water fleas, have taken over the waters. 

The President of the Swiss Professional Fishermen's Association, Reto Leuch, has been fishing in Lake Constance for 30 years. He told Euronews that more and more of the lake's fisheries are having to close.

"The biggest problem with invasive species, new species, is that they compete directly with local species for food. It is frightening. You can't live on fishing anymore. You can't support a family with such a small catch," he explained.

Lake Constance is being studied by scientists from Germany, Austria and Switzerland. At the Eawag research institute near Zurich, they measure the populations of invasive species and cross-check data to understand their impact on the ecosystem.

The total budget of this project is €5.66 million with €2.24 million of support from the European Cohesion Policy. Seven research institutes from the three countries bordering the lake are participating in the project, according to SeeWandel research institute in Dübendorf, Switzerland.

Researchers have counted 37 species of invasive animals and plants. The quagga mussel is one such species and is native to Ukraine. 

"We believe that it arrived via cargo ships, via the Rhine-Danube Canal," explained Silvan Rossbacher, a researcher at Eawag research institute. 

"In the most infested regions of this lake, we have about