Location: Bahia Samborambon, Argentina
Research: Ecology, Behavior and Conservation of the Franciscana Dolphin in Argentina
|The Franciscana dolphin, one of the world's smallest and most endangered dolphins, is endemic to the costal waters of Brazil, Uruguay and Argentina. The IUCN Cetacean Specialist Group has designated the Franciscana one of four "species of concern". The primary issues facing these dolphins are death from entanglement in fishing nets, probably the biggest threat, and habitat degradation and fragmentation by pollution and over fishing. Their natural range includes some of South America's most densely populated coastal areas. AquaMarina- CECIM began its overall, and now long-term, study of the ecology, behavior and conservation of the Franciscana dolphins in 1992. The team has contributed a great deal of the current knowledge of the behavior and ecology of the species. However, little is known about population structure or movement patterns- information that is critical for evaluating impacts and protection measures for these animals. Funds for this project will be used to radio tag Franciscana dolphins to begin compiling the needed data.
Three female Franciscana dolphins were radio tagged with small VHF transmitters and released in Bahia Samborombon in March 2005. The tags were attached to the dorsal fins by a single delrin plastic pin with corrosible nuts. The dolphins were tracked for 6 weeks from a lighthouse, the roof of a hotel, a boat, and from the shore. The maximum range from the highest receiving stations was about 20km. Signals were received from at least one of the tagged dolphins daily, from two individuals on 71% of days, and from all three individuals on 40% of the tracking days. Preliminary analyses by unit effort revealed fairly localized movements by the dolphins, which were mainly recorded in the same area where they were caught. Preliminary analyses suggest a movement pattern associated with the tidal flow, with dolphins coming into the bay during high tide. Though the pilot data set is small, the consistency of findings across the animals suggests that the current designation of a single management stock in Argentina should be re-evaluated. The suggestion of small ranges in areas of heavy artisanal fishing pressure increases the urgency with which protective measures need to be implemented for this species. This study represents the first time that radio tracking has been accomplished with Franciscana dolphins and provides the first data on ranging patterns ever collected for this species.
Co-principal investigators for this study are Pablo Bordino of Wildlife Trust and AquaMarina and Randall Wells of Mote Marine Laboratory and the Chicago Zoological Society. The field research team included members of their staffs, six local fishermen, more than 25 volunteers and graduate/undergraduate students, three park rangers, and four Argentine Coast Guard officers; about 45 people in total. The Argentina Federal Government, through the Secretariat of Natural Resources, declared this project of interest for the country and provided institutional support.