Hardly any fish

Fishing in Lake Constance is at its lowest point

Climate change and invasive species are taking their toll on fish in Lake Constance, and catches have fallen again as a result.

Oh, what times there were when you simply had to hold a fishing line with a maggot in the water and a perch was already wriggling on the hook! Not to mention the huge shoals of whitefish that almost burst the nets of professional fishermen. Such an abundance of fish has been unheard of for a long time, with 2023 representing an absolute low point: The 61 professional fishermen and women on Lake Constance managed a yield of just 133 tons, which was miles below the average of the already meagre previous years (318 tons). Perch, i.e. perch, made up the largest share with 38 tons, followed by pike with 16 tons. White fish such as roach, carp and tench accounted for 46 tons. Roach in particular, which are also known to eat the now infamous quagga mussels, are becoming increasingly important economically despite their many bones.

And what about whitefish, the former "bread and butter" fish of professional fishermen? These are visibly disappearing, with just 10 tons being landed in 2023. And since 1 January 2024, whitefish may no longer be caught anyway; the moratorium is in place for three years.

Too clean, too warm, too many invaders

There are many reasons for the disappearance of the whitefish: the water is virtually "too clean" for this plankton-eating fish species, as well as an ecosystem that has been altered by climate change and invasive species. The latter include the aforementioned quagga mussel, which additionally cleans the water like a filter when it feeds, and the rapidly reproducing stickleback. Because sticklebacks eat young whitefish, the stocking strategy was adjusted at the end of 2023 and now only larger juvenile fish are released. Two pilot projects launched by the International Conference of Plenipotentiaries for Lake Constance Fisheries (IBKF) will now be used to test the extent to which sticklebacks can be caught and utilized.