Abstract
This study aimed to characterize the distribution of botos, Inia geoffrensis, along a 530 km stretch in the middle reaches of the Araguaia River (central Brazil). Data collection was conducted in May (lowering water season) and September (dry season) of 2009. The location and group size of botos were recorded, and the relative density was calculated. The river was divided into nine areas according to geomorphological features; these areas were later grouped into two (low and high) levels of sediment input. The study area was categorized into six types of shoreline habitats: vegetated bank, non-vegetated bank, beach, confluence, bay, and island. A total of 195 sightings (239 botos) were recorded, with the highest density of sightings found in habitats in which tributaries entered the Araguaia River (confluence) followed by the bay habitat. The group size varied from one to three individuals, and single individuals were predominant. The segment with high sediment input also had a higher density of botos compared with the low-sediment segment. Botos-preferred habitats and human activities have a great overlap in Araguaia River. Restrictions of certain human activities, and tourism management would reduce both the intentional and accidental harm of botos in the Araguaia River.
Acknowledgments
This study was financed by the Fundação O Boticário de Proteção à Natureza and received financial support from Petrobrás Ambiental Program “Projeto Mamíferos Aquáticos da Amazônia: Conservação e Pesquisa.” The authors would like to thank the volunteers that took part in the data collection; the Batalhão de Polícia Militar Ambiental de Goiás and IBAMA (GO) for the logistical support; the CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) for the scholarship given to C. C. Araújo; Dr. E.M. Venticinque for the suggestions in the data analyses; Dr. E. Latrubesse for the information on geomorphological data used in this study; and Suzanne Beck for the English revision. The authors also greatly appreciate the comments by John Y. Wang who helped to improve this manuscript.
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