Empirical evidence on the effects of climate on the viability of common carp (Cyprinus carpio) populations in European lakes

Climate is a major driver of species distribution and biological invasions worldwide. In this study, we combined the catches of a widespread and invasive species, the common carp (Cyprinus carpio), with climate data to assess the importance of climate variables on the ability of the species to maintain self-sustaining populations in European lakes. Data were collected on common carp populations in 378 lakes in six European countries over a 16-year period (551 sampling campaigns). All catches followed the same standardized sampling procedure (European CEN gillnets). Climate data consisted of daily averages of air temperature and precipitation. Population self-sustainability was determined by the relative catches of different size classes and the presence of juveniles. The climate data were used to train a classification tree model to characterize the effects of climate on common carp population viability. Results indicated that climate is an important predictor of common carp population viability, which is particularly enhanced under dry conditions and elevated temperatures during spring and summer months. Areas of high population viability strongly overlapped with the invasive range of the species. According to Intergovernmental Panel on Climate Change (IPCC) climate projections, some areas where common carp currently have a low probability of maintaining viable populations will shift toward climatic conditions that enhance their viability and invasion potential.