Impacts of non-native fishes on Iberian freshwater ichthyofauna: current knowledge and gaps

The Iberian Peninsula contains a highly endemic freshwater ichthyofauna that is being homogenized and threatened by an increasing number of non-native fishes. Here, in this paper, I reviewed the literature on the impacts of fish introductions and translocations on the native Iberian ichthyofauna. The aims of the present review were (1) to provide an overview of the already studied and proven impacts as well as of the suggested potential impacts that remain to be tested, (2) to synthesize the current knowledge in the Iberian Peninsula and (3) to suggest future research approaches. Despite some well-documented impacts, an increasing number of non-native fish species and a wide range of diverse ecological situations uncover knowledge gaps which hamper conservation and management efforts. Since the introduction of species is often pointed out as a major cause of extinctions, I encourage research groups and funding agencies to devote more resources to the study of interactions between nonnative and native fishes in order to develop evidence-based species-specific impact assessments.