The Mairenke, which is mostly 15 to 25 centimeters and in exceptional cases up to 35 centimeters long, only occurs in some Upper Bavarian lakes and their large inflows and outflows. Contrary to what its name suggests, Alburnus chalcoides is not a whitefish. It’s a carp fish. And it has one thing in common with the herring: it lives in large schools. This is one of the reasons why the Landesfischereiverband (LFV) has chosen the Mairenke as Bavarian Fish of the Year 2021. Because the herring is the German fish of the year 2021. Since herring in Bavaria only occurs on the plate or in the bread roll, Bavarian fishermen wanted their own fish of the year. “The Mairenke is, as it were, the Bavarian equivalent of the herring,” says LFV President Albert Göttle. In addition, the Mairenke occurs in Germany only in Bavaria. From Göttle’s point of view she is therefore “the perfect representative for the diverse underwater world of our homeland”.
Mairenken have a slim, elongated body. Her scaly dress is silver on the flanks and greenish above. This is why the Mairenke is also called a green compact. Other names are Seelaube or Schiedling. The distribution area of the Mairenken ranges from the Alps to the Caspian Sea. In Bavaria there are Mairenken who can live up to ten years, especially in the Chiemsee, Simssee and Starnberger See lakes. Until the Second World War, they were also available in Schliersee, for example.
Mairenken prefer to stay in the pebbly shore regions of the lakes. When the water gets warmer there in summer, they withdraw to deeper zones. Spawning time is in May, from which the species takes its name. To spawn, the fish move to the very shallow bank areas of lakes or tributaries. A female lays between 15,000 and 30,000 eggs and sticks them to the gravel bottom of the water. The larvae hatch after two or three days. After just under two weeks, the young fish follow the adult animals into the deeper zones of the lakes or tributaries.
The Mairenke was once an appreciated food fish. But like all carp fish, it has many bones. That’s why it’s not so popular anymore. For perch, pike and other predatory fish, however, mayenkers, which feed on plankton and mosquito larvae, are an important prey. Cormorants, goosanders and other fish-eating birds also like to hunt them. For years, however, the stocks have been decreasing. The species was already classified as endangered in the Red List of 2003.
But the main reason is not their many enemies. But the innumerable human interventions in the waters. Weirs and bank structures – especially on the lakes – decimate the habitats of the Mairenken. In addition, they are troubled by the many inputs of nutrients and sediments into the lakes and rivers. This silts up their gravel soils, spawning grounds and habitats for the larvae are lost. The Mairenke is protected under European nature conservation law. “Bavaria has a special responsibility for the species,” says Fischer President Göttle.
To promote the Mairenke, Göttle and the fishermen are calling for the renaturation of lake shores. The most important thing is to restore spawning grounds with shallow water and gravel bottoms, they say. In addition, the traditional walking corridors between the deep zones of the lakes and their inflows and outflows would have to be made open again. The LFV cites the removal of weirs or the construction of hiking aids as examples. The entry of sediments and nutrients into the waters must also be reduced if the species is to have a chance. In order for them to have it, the fishermen tackle it themselves. In 2019, they started a resettlement attempt at Schliersee – with spawning Mairenken from Simssee.