First evidence of Eriocheir sinensis reproduction from Schleswig—Holstein, Northern Germany, western Baltic Sea

Eriocheir sinensis invaded the Baltic Sea over 80 years ago, but there is still little known about mitten crab reproduction in this region. According to present knowledge, reproduction does not occur in the central, eastern and northern parts of the Baltic Sea due to the low salinity present. Sufficient salinity levels for reproduction of the Chinese mitten crab may exist in the western part and in the Kattegat, but published evidence of reproduction is still lacking from the region. Recently however a total of 62 ovigerous females were collected in the eastern part of the Kiel Canal (connecting the North Sea with the Baltic Sea) close to the Kiel Fjord as well as in the Kiel Fjord itself (Schleswig-Holstein, German Baltic Sea coast). The eggs from some of these females were hatched in the laboratory under ‘Kiel Fjord salinity conditions’ and reared to third zoeal stage. Furthermore, larvae were found in plankton samples from the Kiel Fjord and juvenile crabs were present in a lake close to this watershed.