An introduction to river dolphin species

This chapter introduces nine dolphin species (Neophocaena phocaenoides asiaeorientalis, Sotalia guianensis, Sotalia fluviatilis, Pontoporia blainvillei, Inia geoffrensis, Inia boliviensis, Platanista gangetica, Lipotes vexilliter and Orcaella brevirostris) that are discussed in the succeeding chapters of this book and provides brief summaries on each species' population status, habitat condition and looming threats. There are commonalities among the threats for these dolphins and they are linked to human activities. Fishing, dams, and pollution generally affect all of the species with those species near the highest human densities being the most threatened and having the bleakest future. There are of course bright spots in the conservation efforts for these species and some dolphins, such as Inia geoffrensis, seem to be faring well and have a large population size and great distribution. Also, we discuss recent and new contributions of molecular, morphological, and paleontological data that tremendously help our understanding of phylogenetic relationships and evolutionary history of these graceful creatures.