SEASONAL CHANGES IN THE POPULATION STRUCTURE OF THE CHINESE MITTEN CRAB, ERIOCHEIR SINENSIS (H. MILNE EDWARDS) IN THE ODRA/ODER ESTUARY

摘要

A total of 1642 individuals of the Chinese mitten crab, Eriocheir sinensis caught in 2001-2002 in the Odra estuary, were measured. The carapace width was found to range from 46.68 to 92.31 mm (mean width 66.61 ± 7.33 mm); the mean carapace widths offemales and males were 65.40 ± 6.82 mm (46.68-88.85 mm) and 67.96 ± 7.66 mm (47.04-92.31 mm), respectively. There were distinct differences in the numbers of individuals caught in different months. The highest number of crabs (85.44% of all individuals) was caught in autumn, as a consequence of reproductive migration. In the total number of 1642 specimens examined, males were slightly dominant (51.4%), in particular in October (55.31%) and November (52.01%). Females dominated in spring and summer andcontributed 57.2-64.7%.