This video accompanies a peer-reviewed, scientific publication in the journal, Biological Conservation: http://www.sciencedirect.com/science/article/pii/S0006320715302160 It outlines work by biologists (at Fundacion Omacha in Colombia, Oceans Initiative in Canada and the US) and statisticians (at University of St Andrews in Scotland, and NOAA Fisheries in USA) to conduct surveys for two species of river dolphins in Colombian and Peruvian sections of the Amazon River. There are two species of dolphins that live in this river: a grey one (tucuxi, or Sotalia) and a pink one (boto, or Inia). The pink river dolphin is perceived by some fishing communities as competition for fish. There are also reports of deliberate killing of pink river dolphins for bait in a lucrative catfish fishery. Our team compared three sets of survey data since 1993, using advanced statistical methods to account for changing survey methods over time. The trend estimates are preliminary and tentative, but we are reasonably sure that the two species have opposing trends. Our best evidence suggests that the pink river dolphins are declining; and the grey river dolphins are stable or even increasing. Our future research aims to conduct one more survey at the "best" time of year, to improve our confidence that these trends are real. If they are, we will work to understand why the two species are undergoing different trends, so we can identify solutions to benefit pink river dolphins. As we discuss in the paper, there are plans to build many hydroelectric dams throughout Amazonia, which would fragment river dolphin habitat and populations. Omacha works with local communities to understand threats that river dolphins face, and to identify workable solutions. Oceans Initiative is a team of conservation scientists that builds collaborations between biology and statistics to inform evidence-based conservation actions.