At the mussel breeding station at the Kalborn mill, the endangered species of freshwater pearl mussel (Margaritifera margaritifera) and river mussel (Unio crassus) are bred. The aim of this work is to release the mussels back into the river as soon as they have reached a size where they no longer live submerged in the gravel, but are visible in the riverbed.
This significantly increases their likelihood of survival. In addition to the propagation of freshwater mussels, it is very important to improve the quality of the Our as a habitat through various measures. These measures not only benefit the mussels, but also all other aquatic organisms.
Mussel farming is very time-consuming: Firstly, the mussel larvae are collected after they have been expelled by the adult mussels in order to infect the host fish.
The small mussels of less than half a millimetre that develop on the host fish are caught in nets in special facilities and then initially reared in plastic boxes in a temperature-controlled cabinet, where they are fed with single-cell algae.
The mussels grow very slowly, reaching a maximum of two to three centimetres after around four years.
The thick shelled river mussel stays in the rearing station for 2 years, the freshwater pearls mussel for 3-4 years before they are introduced to their original river systems.