Diversity, distribution, and conservation of the Caatinga fishes: Advances and challenges

Abstract

The Caatinga, located in the semiarid region of northeastern Brazil, is dominated by a seasonally dry tropical forest and encompasses a relatively modest hydrographic network, characterized by intermittent water courses. Even the major rivers which are perennial, such as the São Francisco and Parnaíba, have mostly intermittent tributaries within the Caatinga. Despite some early explorations dating back to sixteenth century and the systematic compilation of fish species which started in the beginning of the nineteenth century, until recently the fish fauna of the Caatinga biome has been considered poorly known due to the lack of adequate sampling. The present study assessed the current state of knowledge on this fish fauna, in terms of species richness, endemism, and conservation status, based on a literature review, recent field work, and collection records. Our major result was finding a considerable increment in the species richness in the biome when compared with previous estimates, totaling 386 fish species, 371 of which are native freshwater species, 203 are considered endemic to the hydrographic ecoregions where the Caatinga occurs, 15 are introduced from other basins, and 15 listed species have doubtful taxonomic status. Additionally, 32 species are currently recognized as undescribed. We also highlight that the 33 endangered fish species in the Caatinga are possibly not included in protected areas, and that the conservation units in the biome are not enough to ensure protection for endemic and endangered fish species.