Both cetaceans in the Brazilian Amazon show sustained, profound population declines over two decades

Silva, Vera Maria Ferreira da; Carvalho, Carlos Edwar Freitas de; Dias, Rodrigo L.; Martin, Anthony Richard

Artigo

Both cetaceans in the Brazilian Amazon show sustained, profound population declines over two decades

Obligate river dolphins occur only in the rivers of Asia and South America, where they are increasingly subject to damaging pressures such as habitat degradation, food competition and entanglement in fishing gear as human populations expand. The Amazon basin hosts two, very different, dolphins—the b...

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Autor principal:	Silva, Vera Maria Ferreira da
Outros Autores:	Carvalho, Carlos Edwar Freitas de, Dias, Rodrigo L., Martin, Anthony Richard
Grau:	Artigo
Idioma:	English
Publicado em:	PLoS ONE 2020
Assuntos:	Brasil Ecology Environment Geography Nonhuman Population Density Population Growth Pressure Survival Rate Toothed Whale Animals Cetacea Population Dynamics Statistical Model Animalss Brasil Cetacea Models, Statistical Population Dynamics
Acesso em linha:	https://repositorio.inpa.gov.br/handle/1/14660

id	oai:repositorio:1-14660
recordtype	dspace
spelling	oai:repositorio:1-14660 Both cetaceans in the Brazilian Amazon show sustained, profound population declines over two decades Silva, Vera Maria Ferreira da Carvalho, Carlos Edwar Freitas de Dias, Rodrigo L. Martin, Anthony Richard Brasil Ecology Environment Geography Nonhuman Population Density Population Growth Pressure Survival Rate Toothed Whale Animals Cetacea Population Dynamics Statistical Model Animalss Brasil Cetacea Models, Statistical Population Dynamics Obligate river dolphins occur only in the rivers of Asia and South America, where they are increasingly subject to damaging pressures such as habitat degradation, food competition and entanglement in fishing gear as human populations expand. The Amazon basin hosts two, very different, dolphins—the boto or Amazon river dolphin (Inia geoffrensis) and the smaller tucuxi (Sotalia fluviatilis). Both species have wide geographical ranges and were once considered to be relatively abundant. Their IUCN Red List conservation status of Data Deficient (DD), due to limited information on threats, ecology, population numbers and trends, did not initially cause alarm. However, the development of dolphin hunting to provide fish bait at around the beginning of this millennium broadly coincided with the onset of a widespread perception that numbers of both species were in decline. Consequently, the need for population trend data to inform conservation advice and measures became urgent. This paper presents a 22-year time series of standardised surveys for both dolphins within the Mamirauá Reserve, Amazonas State, Brazil. Analysis of these data show that both species are in steep decline, with their populations halving every 10 years (botos) and 9 years (tucuxis) at current rates. These results are consistent with published, independent information on survival rates of botos in this area, which demonstrated a substantial drop in annual survival, commencing at around the year 2000. Mamirauá is a protected area, and is subject to fewer environmental pressures than elsewhere in the region, so there is no reason to suspect that the decline in dolphins within the Reserve is more pronounced than outside it. If South America’s freshwater cetaceans are to avoid following their Asian counterparts on the path to a perilous conservation status, effective conservation measures are required immediately. Enforcement of existing fishery laws would greatly assist in achieving this. © 2018 F. da Silva et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 2020-04-24T17:00:00Z 2020-04-24T17:00:00Z 2018 Artigo https://repositorio.inpa.gov.br/handle/1/14660 10.1371/journal.pone.0191304 en Volume 13, Número 5 Attribution-NonCommercial-NoDerivs 3.0 Brazil http://creativecommons.org/licenses/by-nc-nd/3.0/br/ application/pdf PLoS ONE
institution	Instituto Nacional de Pesquisas da Amazônia - Repositório Institucional
collection	INPA-RI
language	English
topic	Brasil Ecology Environment Geography Nonhuman Population Density Population Growth Pressure Survival Rate Toothed Whale Animals Cetacea Population Dynamics Statistical Model Animalss Brasil Cetacea Models, Statistical Population Dynamics
spellingShingle	Brasil Ecology Environment Geography Nonhuman Population Density Population Growth Pressure Survival Rate Toothed Whale Animals Cetacea Population Dynamics Statistical Model Animalss Brasil Cetacea Models, Statistical Population Dynamics Silva, Vera Maria Ferreira da Both cetaceans in the Brazilian Amazon show sustained, profound population declines over two decades
topic_facet	Brasil Ecology Environment Geography Nonhuman Population Density Population Growth Pressure Survival Rate Toothed Whale Animals Cetacea Population Dynamics Statistical Model Animalss Brasil Cetacea Models, Statistical Population Dynamics
description	Obligate river dolphins occur only in the rivers of Asia and South America, where they are increasingly subject to damaging pressures such as habitat degradation, food competition and entanglement in fishing gear as human populations expand. The Amazon basin hosts two, very different, dolphins—the boto or Amazon river dolphin (Inia geoffrensis) and the smaller tucuxi (Sotalia fluviatilis). Both species have wide geographical ranges and were once considered to be relatively abundant. Their IUCN Red List conservation status of Data Deficient (DD), due to limited information on threats, ecology, population numbers and trends, did not initially cause alarm. However, the development of dolphin hunting to provide fish bait at around the beginning of this millennium broadly coincided with the onset of a widespread perception that numbers of both species were in decline. Consequently, the need for population trend data to inform conservation advice and measures became urgent. This paper presents a 22-year time series of standardised surveys for both dolphins within the Mamirauá Reserve, Amazonas State, Brazil. Analysis of these data show that both species are in steep decline, with their populations halving every 10 years (botos) and 9 years (tucuxis) at current rates. These results are consistent with published, independent information on survival rates of botos in this area, which demonstrated a substantial drop in annual survival, commencing at around the year 2000. Mamirauá is a protected area, and is subject to fewer environmental pressures than elsewhere in the region, so there is no reason to suspect that the decline in dolphins within the Reserve is more pronounced than outside it. If South America’s freshwater cetaceans are to avoid following their Asian counterparts on the path to a perilous conservation status, effective conservation measures are required immediately. Enforcement of existing fishery laws would greatly assist in achieving this. © 2018 F. da Silva et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
format	Artigo
author	Silva, Vera Maria Ferreira da
author2	Carvalho, Carlos Edwar Freitas de Dias, Rodrigo L. Martin, Anthony Richard
author2Str	Carvalho, Carlos Edwar Freitas de Dias, Rodrigo L. Martin, Anthony Richard
title	Both cetaceans in the Brazilian Amazon show sustained, profound population declines over two decades
title_short	Both cetaceans in the Brazilian Amazon show sustained, profound population declines over two decades
title_full	Both cetaceans in the Brazilian Amazon show sustained, profound population declines over two decades
title_fullStr	Both cetaceans in the Brazilian Amazon show sustained, profound population declines over two decades
title_full_unstemmed	Both cetaceans in the Brazilian Amazon show sustained, profound population declines over two decades
title_sort	both cetaceans in the brazilian amazon show sustained, profound population declines over two decades
publisher	PLoS ONE
publishDate	2020
url	https://repositorio.inpa.gov.br/handle/1/14660
_version_	1787144532756791296
score	11.653393

Both cetaceans in the Brazilian Amazon show sustained, profound population declines over two decades

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