Reproductive biology and life cycle of the invasive crayfi sh Procambarus clarkii (Crustacea: Decapoda) in diverse aquatic habitats of South-Western Spain: Implications for population control

Since its introduction to southern Spain 30 years ago, the red swamp crayfi sh Procambarus clarkii has established stable populations in both natural and man-made water bodies of the Lower Guadalquivir river basin, including the Donana National Park. In order to provide background data for potential management measures, we assessed the fertility, timing of and size at reproduction for this species at 11 sites differing in hydroperiod and habitat characteristics. Fecundity (in terms of the number of eggs per female) was size dependent, with reproduc- tive output per unit of weight being highest in large females from permanent water bodies, especially those from river branches. Size at reproduction was related to water temperature, population density, and the length of the hydroperiod. The smallest mature individuals were found in rice fi eld habitats, which had the highest densities ob- served, were fi lled with water throughout the summer, and had the longest dry period of all the habitats studied (6 months). In rice fi elds, recruitment peaks were observed in early summer and autumn. In permanent water bodies, most recruitment took place in late autumn and spring, whereas in water bodies that dry out in the summer, recruit- ment was mainly in the autumn or early winter. In order to reconcile confl icting interests between economy and ecology in the study area, we propose the transformation of unused rice fi elds, where crayfi sh densities are high, into crayfi sh culture grounds. Creating a hydrological cycle similar to that found in river branches would guarantee their large size at maturity.