Ecology of River Dolphins and Fish at Confluence Aggregations in the Peruvian Amazon
Bodmer, Richard E. (University of Kent)
Henderson, Peter (PISCES Conservation Ltd)
Spence, Claire (University of Kent)
Garraty, Tara A. O. (University, Bangor)
Chota, Kimberlyn (Fundación Latinoamericana para el Trópico Amazónico)
Uraco, Paola (Fundación Latinoamericana para el Trópico Amazónico)
Antunez, M. (Fundación Latinoamericana para el Trópico Amazónico)
Fang, Tula (Fundación Latinoamericana para el Trópico Amazónico)
Butcher, Jack (University of Kent)
Bicknel, Jake E. (University of Kent)
Pizuri, Osnar (Fundación Latinoamericana para el Trópico Amazónico)
Mayor Aparicio, Pedro Ginés (Universitat Autònoma de Barcelona. Departament de Sanitat i d'Anatomia Animals)

Date:	2025
Abstract:	Amazon River dolphins often form multi-species aggregations at water confluences. This study used a multi-year data set to examine dolphins, fish, and geomorphology at dolphin aggregations. Methods included dolphin transect surveys, dolphin point counts, net and line fish captures, side-scan sonar, and eDNA analyses at five dolphin aggregations and two control sites. Amazon River dolphins (Inia geoffrensis and Sotalia fluviatlis) are typically found at aggregation sites that occur at water confluences that have greater dolphin numbers than control sites. The confluences had riverbed depressions averaging six metres in depth where fish were concentrated. Pink river dolphins preferred to form aggregations in flooded forest tributaries and large rivers, while grey river dolphins preferred the larger rivers. There were eighty-nine fish species at the confluences within the size of fish consumed by dolphins, and a higher abundance of fish occurred in and around the aggregation sites compared to control sites. The number of dolphins present at the aggregation sites correlated with fish abundance. Dolphin life history, such as fishing, resting, raising calves, and social interactions, occur at the aggregation sites. The aggregation sites are important conservation areas of the endangered pink and grey river dolphins, and through their folklore, Indigenous people living at confluence sites assist in the conservation of the aggregations and have lived with dolphins at confluences for thousands of years, contributing to their survival.
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Pink river dolphin ; Grey river dolphin ; Amazon fish ; Dolphin aggregations ; River confluences
Published in:	Fishes, Vol. 10, Num. 10 (October 2025) , p. 495, ISSN 2410-3888

DOI: 10.3390/fishes10100495

19 p, 2.0 MB

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