A comparative analysis of two allochthonous populations of the Chinese mitten crab (Eriocheir sinensis H.!Milne-Edwards, 1853) from the Szczecin Lagoon (NW Poland) and San Francisco Bay (US west coast)

Selected biological and morphometric characters of two populations of the non-indigenous Chinese mitten crab, one front the Szczecin Lagoon (SL) and the other from San Francisco Bay (SFB), both sampled in autumn, were analysed. The SL crabs showed a significantly higher individual weight, length and carapace width. Males accounted for 55% (87 individuals) of the 179 SL crabs, and 62.9% (90 individuals) of the SFB crabs. Statistical analysis of metric characters, expressed as a percentage of carapace width (X-2), enabled four diagnostic characters to be identified: abdomen width (X-11), carapace height (X-3) left claw length (X-7) and carapace length (X-1). These jointly explain 71.75% of the differences between the SL and SFB crabs and are indicative of the distinctness of the populations.