Goldfish and raccoons: a threat to our native wildlife!

Goldfish and raccoons: a threat to our native wildlife!

Serious problems are emerging in the waters around Lake Constance and the regional nature reserves. Goldfish, originally kept as pets, threaten local biodiversity. These fish species, which are often intentionally released into waterways, eat the eggs and larvae of amphibians, endangering their survival. There is a particularly worrying example in the Schaichtal nature reserve near Dettenhausen. According to Sabrina Lorenz from the Tübingen regional council, the release of goldfish there even led to a decline in the amphibian population to almost zero.

Fighting these invasive fish species is expensive: around 30,000 euros will be required for measures to remove the goldfish in Schaichtal. Goldfish are not the only problematic neobiota in the region. Other invasive species such as raccoons and giant hogweed are also pushing into our ecosystem.

The quagga mussel and its threat

Another major problem is the invasive quagga mussel, which has been wreaking havoc in Lake Constance since 2016. Estimates speak of around 4,000 mussels per square meter. These little beasts make the lake less nutrient-rich and clog water pipes, which also endangers the drinking water supply. These mussels were introduced by boats from the Black Sea region around ten years ago and now pose a serious threat to the entire ecosystem.

The focus of the International Lake Constance Conference (IBK) is now on studying natural predators of the quagga mussel, such as carp-like fish. Chemicals are not a solution as they would be too dangerous for the lake's delicate ecosystem. A study scheduled to run until 2028 aims to promote fish density and thereby potentially achieve natural regulation of this invasive species.

Invasive species under pressure

Around 900 neobiota species are established in Germany, which corresponds to around 1% of the total population of around 74,000 species. The largest group among them are plants (neophytes), followed by invertebrates and vertebrates (neozoa). This presence of neobiota species has increased significantly over the last 170 years, closely related to global trade and increased traffic. Of particular concern is climate change, which makes it easier for invasive species to spread into new areas.

It remains to be seen what measures will be taken to protect waterland biodiversity. A sustainable strategy to combat invasive species is urgently needed to preserve the Lake Constance ecosystem and the surrounding regions.

For more information about invasive species and their impact on local ecosystems, check out Schwäbische.de, n-tv.de and bfn.de.