the Name is a Testament to the hazard. The Bach shell is actually called the common river mussel. At the beginning of the last century it was widely used in Switzerland is still far. All of this changed over the years. Fertilizers and pesticides from agriculture, constructions, siltation and other factors have wiped out the shell, which can be up to 10 centimetres tall, almost. Today it is almost only in the upper reaches of the larger rivers and in streams, which is why they are second only to the Bach shell.
Before the turn of the Millennium, the Bach shell in the Canton of Zurich has demonstrated in some two dozen Places. In the meantime, there are only three references: in the Rhine, in the Ford of a brook, and in most Bach in Wetzikon. In the Latter, Anna Carlevaro was recently on the search. The biologist accompanied on behalf of the Canton of a breeding program. For the Start you found in three days just four Bach shells. "Working with shells can be frustrating," says the Tessinerin. "You can hardly find any."
minnows spread the mussels
These four shells are now in Langnau am Albis. In the old water reservoir between the Langenberg wildlife Park, and the Albis pass, the fishing-club Thalwil built by Carlevaro, a system for the shells. The Location is ideal because of the club's trout there, is breeding in addition to stone crabs and Creek also minnows, such as the Association's President and shellfish lobbyist Rolf honey explained. Small minnows or other fish clams is a Partner of the Bach and do not help in the dissemination of the art. In the case of trout, it works – no one knows why.
reproduction in bivalve molluscs: The males give their cum into the water. The females absorb it through their gills, in their pockets, the eggs are fertilized. The female brook mussel shoots after about five weeks, a jet of water with kitzekleinen mussel larvae from their Opening. These so-called Glochidia on the gills of minnows. After a few weeks, the Glochidia drop. You are then less than 1 mm in size. In the Sand they grow up to be young mussels. In the nature, you can stay there for up to three years and dig out by yourself.
work with the magnifying glass
In Langnau, the ten – year-old mother are shells- they can be up to 30 years old – currently in a "Verrichtungsbox" how Carlevaro says half-seriously. Visit to you have from four to eight-year-old mussels from the river Rhine. The minnows swim in a different pool. After the merging and Discarding of the fish, a lot of work is waiting for the biologist. With the magnifying glass, you will separate the many open, dead young shells of the Living. The latter come in four pools, with a centimeter-thick layer of sand.
The water in these pools must be changed every week. This Original is carted-most stream-water. The fishermen's Association has set up three tanks of 1000 liters. Treasury expects the breeding cycle, with a requirement of 6000 litres.
"The shells have no Lobby,"
the goal, in the summer of 2020, a few hundred young clams in the Creek in the Zurich Oberland to suspend. Why this big effort? "Clams belong in our water world, like fish or crabs," says treasure. Seven of the eight native mussel species are endangered to threatened. Worst of all is the Bach shell. Only the Large pond mussel in the lakes is not at risk. "The mussels don't have a Lobby like the edible fish," says Carlevaro. "It is sad that it had to come this far."
The Federal government has recognized the Situation and the brown mussel as a "national priority species" classified. This obliges the cantons to launch action plans and to take measures for the protection and promotion. The cantons of Zurich, St. Gallen, Aargau and Schaffhausen with a draw, in Lucerne, with its clam-rich shores of lake Lucerne pinches. That's where the money is missing, allegedly. For the time being, the larger program includes a genetics analysis. It collects data. Because, we know surprisingly little about these animals , this is the place with your "feet" – so the strong muscle between the two Valves, means to loose a Meter of the day behind.
In the Canton of Aargau is a tank with a breeding, the reintroduction of the Bach shell. The Zurich-based breeding program is the rescue of the most Bach-Population from extinction. Carlevaro's predecessors had tried, with Glochidia "vaccinated" fish suspend. However, this so-called Soft method didn't work. And now, time is of the essence. (Tages-Anzeiger)
Created: 18.05.2019, 08:36 PM