Frequently asked questions about quagga mussels

The two mussels are similar, but there are some differences. Whereas the zebra mussel is rather flat and concave on the underside with a keel on the side, the quagga mussel is convex and has a rounded keel on the side. The most pronounced difference is that the quagga mussel tips over when placed on its underside, while the zebra mussel is more stable. Another distinguishing feature is the pattern: the zebra mussel often displays the typical zigzag pattern, which is less common in the quagga mussel. The line on the underside of the quagga mussel is also curved, whereas it is straight in the zebra mussel. For more detailed information, please consult the identification guide (German, PDF) of the Swiss Water, Gas and Heat Association.

Yes, it does not stop at national borders and is now widespread in large parts of Europe. However, it is a particular problem in the deep lakes of the Alpine foothills because, unlike in the shallow water zones of its original habitat in the Black Sea region, only a small number of birds and fish eat it here. Generally, the following is applicable: The denser the network of boat transport, the greater the risk of further spreading if no precautions are taken.

The growth of quagga mussels can cause major economic problems, especially on and in infrastructure, namely, water pipes that carry lake water. The mussels clog intake pipes or attach themselves to installations. Many water works on the affected lakes therefore have high annually recurring cleaning costs. Conversions and new constructions are sometimes necessary, cooling systems have to be replaced or a completely new waterworks must be built.

However, it is currently almost impossible to estimate the actual economic costs for Switzerland because there is no overview of the affected installations. Many businesses and municipalities have not gone public with their quagga mussel problems or have not yet recognised them. The number of unreported cases is certainly high. What can be said, however, is that we are talking about hundreds of millions of francs.

Eawag does not have the resources to identify all mussel specimens found in Switzerland. However, please feel free to contact us. Please note the rules for shipping quagga mussels. Alternatively, you can contact the cantonal authorities or a local environmental agency.

There is currently no standardised regulation in place throughout Switzerland. We generally recommend that you always check, clean and dry the equipment well before transitioning between water bodies during use for boating, fishing, diving, surfing, stand-up paddling, etc. The measures are not only effective against the quagga mussel, but also help to prevent the introduction and spread of other invasive species.

Certain cantons have introduced a mandatory ship reporting and cleaning for ship with a registration plate when changing waters, or they prohibit the launching of boats from other cantons. Many cantons use information boards and posters to provide information about the measures taken along bodies of water.

If in doubt, we recommend asking the canton in which you wish to launch. You can find information here, for example:

Central Switzerland (website in German)

Canton of Bern (website in German, French)

Canton of Zurich (website in German)

We do not recommend eating quagga mussels. From a culinary point of view, quagga mussels are small, have little flesh and a chewy texture, making them less appealing than scallops. They may also be contaminated with pollutants. This is because, as filter feeders, they can absorb pollutants from the water, such as antibiotics, endocrine disruptors and heavy metals such as mercury, lead and cadmium. These substances can pose serious health risks. Furthermore, there is a possibility that quagga mussels harbour harmful bacteria and pathogens.