Spread of the Chinese mitten crab (Eriocheir sinensis H. Milne!Edwards) in Continental Europe:: analysis of a historical data set

The Chinese mitten crab, Eriocheir sinensis (H. Milne Edwards), is an invasive species that lives as an adult predominantly in freshwater but migrates seawards to breed. It has spread via ballast water and/or intentional introduction to Continental Europe, Southern France, U.S.A. (San Francisco Bay) and the United Kingdom. Analysis of detailed historic data from the outbreak in Europe was digitised and analysed using Geographical Information Software. This revealed that there were two separate invasions in Northern Europe and Southern France, with an average range expansion during the peak period of 562 km/year from 1928-1938 (Northern Europe) and 380 km/year from 1954-1960 in Southern France. Size class distribution data from the lower estuary of the River Elbe (Germany) (1932-1936) illustrate migration patterns to and from the estuary over the year. Marking experiments determined that the mean rate of downstream migration for adults was 11.5 km/day (SD 3.54; n=7), up to a maximum of 18.1 km/day. The carapace width of upstream-migrating animals increased by 3 mm/100 km. The peak period for upstream migration was March to July, followed by the downstream season from July to September. This data set, extracted from historic references, represents one of the most complete pictures of the life cycle and spreading behaviour of this alien invader.