Amazon river dolphins Inia geoffrensis are on the path to extinction in the heart of their range

TY - JOUR

T1 - Amazon river dolphins Inia geoffrensis are on the path to extinction in the heart of their range

AU - Martin, A. R.

AU - Da Silva, V. M.F.

N1 - Funding Information: This study was part of Projeto Boto, a cooperative agreement between the National Amazon Research Institute (Instituto Nacional de Pesquisas da Amazônia; INPA/MCTIC) and the Mamirauá Sustainable Development Institute (MSDI-OS/MCTIC). We thank the many interns of Projeto Boto who contributed to data collection, and Admisson M. Carvalho, who participated in 90% of the surveys. Funding was provided by INPA/Ministério da Ciência, Tecnologia, Inovações e Comunicações (MCTIC), and Associação dos Amigos do Peixe-boi (AMPA)/Petrobras Socioambiental Program. Publisher Copyright: Copyright © The Author(s), 2021. Published by Cambridge University Press on behalf of Fauna & Flora International.

PY - 2022/7

Y1 - 2022/7

N2 - Riverine cetaceans are threatened globally by increasing anthropogenic impacts, and the Yangtze river dolphin Lipotes vexillifer is already extinct. The Amazon river dolphin Inia geoffrensis is widely distributed, but is categorized as Endangered on the IUCN Red List. Drowning in gillnets and being hunted for fish bait are probably the main causes of its decline. A long-term (25-year) study of the biology and ecology of I. geoffrensis in and near the Mamirauá Reserve in Amazonas state, Brazil, has produced estimates of survival and reproductive rates based on the individual recognition of > 650 animals. Concurrently, monthly standardized counts of dolphins along a fixed transect in the Reserve over 22 years demonstrated a sustained, profound decline. In this study we tested whether the measured rate of population decline is consistent with population parameters estimated from independent data, using population viability analysis. With the known parameters as input, programme Vortex predicted population extinction in all scenarios and a 95% loss of dolphins within 50 years. With default parameters, the model predicted a 5.5% annual decline, which is consistent with that observed. We conclude that the Amazon river dolphin population is in severe decline because of human pressures, even in one of the better protected parts of its range. Unless the accidental and deliberate killing of this species is rapidly reduced, it is highly likely that the Amazon river dolphin will follow its Yangtze counterpart to extinction.

AB - Riverine cetaceans are threatened globally by increasing anthropogenic impacts, and the Yangtze river dolphin Lipotes vexillifer is already extinct. The Amazon river dolphin Inia geoffrensis is widely distributed, but is categorized as Endangered on the IUCN Red List. Drowning in gillnets and being hunted for fish bait are probably the main causes of its decline. A long-term (25-year) study of the biology and ecology of I. geoffrensis in and near the Mamirauá Reserve in Amazonas state, Brazil, has produced estimates of survival and reproductive rates based on the individual recognition of > 650 animals. Concurrently, monthly standardized counts of dolphins along a fixed transect in the Reserve over 22 years demonstrated a sustained, profound decline. In this study we tested whether the measured rate of population decline is consistent with population parameters estimated from independent data, using population viability analysis. With the known parameters as input, programme Vortex predicted population extinction in all scenarios and a 95% loss of dolphins within 50 years. With default parameters, the model predicted a 5.5% annual decline, which is consistent with that observed. We conclude that the Amazon river dolphin population is in severe decline because of human pressures, even in one of the better protected parts of its range. Unless the accidental and deliberate killing of this species is rapidly reduced, it is highly likely that the Amazon river dolphin will follow its Yangtze counterpart to extinction.

KW - Amazon river dolphin

KW - Brazil

KW - Endangered species

KW - extinction

KW - fishery interactions

KW - Inia geoffrensis

KW - population viability analysis

UR - https://www.scopus.com/pages/publications/85118855171

U2 - 10.1017/S0030605320001350

DO - 10.1017/S0030605320001350

M3 - Article

AN - SCOPUS:85118855171

SN - 0030-6053

VL - 56

SP - 587

EP - 591

JO - Oryx: The International Journal of Conservation

JF - Oryx: The International Journal of Conservation

IS - 4

ER -