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

Dirk Dirk Brandis,Thurid Otto

doi:10.3391/ai.2011.6.s1.015

Abstract

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.

Highlights

The native range of Chinese mitten crab Eriocheir sinensis
The purpose of this study is to present the first evidence of Eriocheir sinensis successfully reproducing off the German Baltic Sea coast
Seven zoea of Eriocheir sinensis were found in the plankton samples caught at two sample places in the Kiel Fjord where it merges into the Kiel Bight: 4 zoea were collected on 25 May 2009 at Strande and 3 zoea were found in a sample from Schilksee taken on 11 June 2009 (Figure 1, Table 1)

Summary

Introduction

The native range of Chinese mitten crab Eriocheir sinensis (H. Milne-Edwards, 1853) (Crustacea, Decapoda, Varunidae) reaches from the eastern pacific coast of China to the Korean Peninsula. From there the species spread out across a large part of northern Europe including almost the entire coastal Baltic Sea and its adjacent rivers (Bacevičius and Gasiūnaitė 2008; Herborg et al 2003; Normant et al 2000; Ojaveer et al 2007; Panning 1938; Panov et al 2003; Peters 1938), where it is a common by-catch, albeit in much lower numbers than in adjacent rivers of countries bordering the North Sea. The Chinese mitten crab has a catadromous life cycle and presently it is generally agreed, that the German population of Eriocheir sinensis can only reproduce successfully in the North Sea due to the appropriate salinities - between 15 close to the river mouths and 32 offshore (Cohen and Weinstein 2001 and references therein).

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Conclusion