Invasive dynamics of the crayfish Procambarus clarkii (Girard, 1852) in the international section of the River Minho (NW of the Iberian Peninsula)

Procambarus clarkii (Girard, 1852) is a well-established invasive species in many worldwide aquatic ecosystems and is responsible for several ecological and economic impacts. This study examines the major factors responsible for its invasive dynamics in the international section of the River Minho (north-west Iberian Peninsula). Data collected from June 2007 to May 2011 showed that abundance and biomass increased in the first 3years of sampling, but suffered a decrease in the fourth year. Higher abundance and biomass were always found from May to October. These higher values have a clear relationship with water temperature and probably reflect higher activity and mobility. The sex-ratio was 1.08:1 in favour of females; eggs start to appear in May/June and the majority of juveniles in August/September. Information collected in this study is extremely important for future management actions that could be applied to this invasive species. Accordingly, we propose that control actions to minimize P. clarkii impacts in this system, such as intensive trapping, should be applied during late spring/early summer, when the catches are higher, the females are dominant, and before juvenile recruitment.Special thanks to Eduardo Martins and Mário Araújo for laboratory and field assistance and to Tim van Nus and William McDowell for careful revision of the manuscript.publishe