Abstract
The endangered Bolivian river dolphin (Inia boliviensis) is increasingly threatened by agricultural river modifications, which can cause stranding in shallow water or isolation into lagoons separated from the river.1-3 Intensive soybean field management using unknown levels of pesticides and contaminants is transforming the natural riparian forest. Approximately 18 dolphins have been isolated from the Rio Grande in a lake since 2012, which has decreased in size from 26 km2 in 1986 to 3 km2 in 2016.2 Using nets, manual capture, and truck transportation, we translocated six dolphins (five male, one female) from the lake back to the Rio Grande. Each dolphin underwent physical examination, diagnostic sampling, and satellite tag placement (n=3). Diagnostic testing included capture and release blood gas analysis; complete blood count; serum biochemistry; blowhole, urogenital, oral and fecal cytology ± culture; and fecal parasite examination. Capture to release took on average 4.8 h and all dolphins tolerated the process without complications. Significant findings included minor skin lesions, healed fractures, dental morphology variations, and fecal trichurids and strongyles. Clinical pathology results were unremarkable. Escherichia coli, Staphylococcus aureus, and Klebsiella oxytoca were cultured from oral, fecal and/or blowhole samples. Future work includes monitoring movements via satellite, Brucella and Leptospira serology, serum pollutant concentration, translocating remaining dolphins, and public education. Living at the intersection of natural rivers, agricultural expansion, and human settlement, Bolivian river dolphins are sentinels of ecosystem health. This and this project’s team diversity, from villagers to veterinarians, emphasize the importance of a One Health approach to conservation.
Acknowledgments
The authors thank the American Association of Zoo Veterinarians Wild Animal Health Fund for awarding this project financial support, and the John G. Shedd Aquarium Animal Response Team for financial support for the primary author’s travel. Authors also thank Jamie Palmer of the Saint Louis Zoo Institute for Conservation Medicine for assistance with project coordination, Dr. Nicole Stacy for cytological expertise, and Mary Ann Kingsley and Kaitlin Green, RVT of The Maryland Zoo for their support in planning this project. We extend an especially warm thanks to the biologists and staff of the Museo de Historia Natural Noel Kempff Mercado for field assistance, and the forest firefighters and air and water rescuers of the Gobierno Autonomo Departamental Santa Cruz for their logistical expertise in making the field station, capture, and transports successful and safe.
Literature Cited
1. da Silva V, Trujillo F, Martin A, Zerbini AN, Crespo E, Aliaga-Rossel E, Reeves R. Inia geoffrensis. The IUCN Red List of Threatened Species 2018: e.T10831A50358152. Available from http://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T10831A50358152.en.
2. Escobar-WW M, Lineo I, Catari JC, Ledezma JP, Villaroel D, Bejarano E, Paniagua L, Ortega L, Blanco R, Avila G, Martinez A. Diagnóstico del estado de conservación del delfín de rio Inia boliviensis en la cuenca del rio Grande. [Conservation status diagnostic of the river dolphin Inia boliviensis in the Rio Grande basin] Museo de Historia Natural Noel Kempff Mercado. [Noel Kempff Mercado Natural History Museum]. 2013. p.183
3. Gomez-Salazar C. River dolphins as indicators of ecosystem degradation in large tropical rivers. PhD dissertation, Dalhousie University. 2012.