Fishers' Knowledge Indicates Extensive Socioecological Impacts Downstream of Proposed Dams in a Tropical River

Runde, Anne; Hallwass, Gustavo; Silvano, Renato Azevedo Matias

doi:10.1016/j.oneear.2020.02.012

Cited by 33 publications

(34 citation statements)

References 86 publications

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“…Previous studies have shown that local riverine people in the Brazilian Amazon tend to avoid consumption of large catfish, which are considered as food taboos (Begossi, Hanazaki & Ramos, ). However, both the results presented here and from a recent study (Runde, ) indicate that large catfish are now considered as important commercial fish in the Tapajós River.…”

Section: Discussionmentioning

confidence: 49%

Fishers’ knowledge indicates temporal changes in composition and abundance of fishing resources in Amazon protected areas

Hallwass

Schiavetti

Silvano

2019

Animal Conservation

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The local ecological knowledge (LEK) of fishermen has been applied to reconstruct temporal patterns of resource abundance and to assess resource exploitation, especially in tropical ecosystems. Protected areas (PAs) are the main conservation measure in the Amazon, but their efficacy to improve fisheries is poorly known. The main goal of this study was to apply fishermen' LEK to evaluate temporal changes in composition and abundance of exploited fish species among three different categories of PAs in the Tapaj os River, Brazilian Amazon. We interviewed 203 fishers about their highest fish catches, and the main fish caught at two time periods: the beginning of their fishing careers and currently. Fishers' LEK indicated decreases in citations of larger-bodied fishes and in reported catches over time, evidencing a gradient of conservation according to PA's time of establishment and management rules. We noticed higher changes (reduced catches and smaller fish exploited) in the Environmental PA, established 10 years ago and lacking management plan and buffer zone. In National Forest, which was created 40 years ago with more restrictive management rules, fish composition and catches included larger commercial fish. The Extractive Reserve, which was created 15 years ago and lacks specific fishing rules, may be in an intermediate stage, as large fish and highest catches decreased over time, but medium and large fish are still exploited. Fishers' LEK can be an invaluable but neglected source of data on temporal patterns of fishing pressure and conservation needs, especially in tropical megadiverse, poorly known and threatened rivers.

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Section: Discussionmentioning

confidence: 49%

Fishers’ knowledge indicates temporal changes in composition and abundance of fishing resources in Amazon protected areas

Hallwass

Schiavetti

Silvano

2019

Animal Conservation

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“…These people are descendants of indigenous Brazilians and Portuguese colonizers, but more recently there has been an immigration of people from the northeast of Brazil (Begossi, 1998). The small-scale fisheries are predominant in these tropical rivers in the Brazilian Amazon (Bayley and Petrere, 1989;Hallwass et al, 2011Hallwass et al, , 2020a, where fishing is considered to be amongst the most important economic activities, both for subsistence and for commercialization, in addition to smallscale agriculture and livestock (McGrath et al, 2008;Runde et al, 2020). The level of formal education of fishers limits their reallocation to other economic activities not directly related to the use of natural resources (Lima et al, 2012).…”

Section: Study Populationmentioning

confidence: 99%

“…Fishers were interviewed individually, usually in their homes and before each interview the research was explained and consent was requested from the fisher to participate in the interview. After the interview, the interviewed fisher was solicited to indicate another fisher in the community who would fits the same criteria, through the snowball method, which has been successfully applied in previous studies on fisher's LEK in the Brazilian Amazon (Hallwass et al, 2013(Hallwass et al, , 2020bRunde et al, 2020). The interviews were based on a semi-structured questionnaire (Supplementary Material 3), in which photos of the fish were shown, always in the same order, following previous methods of ethnoecological studies Begossi, 2002, Begossi, 2012).…”

Section: Interviewsmentioning

confidence: 99%

“…Such information from fishers' LEK, which can be mixed or incorporated into conventional research data, can be an important source for creating new ecological hypotheses (Silvano and Valbo-Jørgensen, 2008;Turvey et al, 2010). Among its many applications, fishers' LEK can contribute to identify environmental changes and assess impacts from development projects on fisheries resources (Hallwass et al, 2013;Baird et al, 2020;Runde et al, 2020;Santos et al, 2020), to calculate fish trophic level and to indicate patterns of mercury bioaccumulation in fish (Silvano and Begossi, 2016), besides providing needed data on the abundance patterns, occurrence and distribution of threatened species (Bender et al, 2014;Zapelini et al, 2017;Lopes et al, 2018;Freitas et al, 2020;Hallwass et al, 2020b;Ribeiro et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…In the Brazilian Amazon, there are two large protected areas, besides indigenous lands, in the region of the Lower Tapajós, which is a clear water river (Keppeler et al, 2017). However, dams and other projects are planned in the upstream region of the Tapajós River and its tributaries, including some projects already approved and built, which represent a challenge for the conservation of aquatic biodiversity (Fearnside, 2015;Winemiller et al, 2016;Athayde et al, 2019;Runde et al, 2020). The Tocantins River, which is another clear water river, can be considered one of the most impacted sub-basins in the Brazilian Amazon (Barthem et al, 2005), mainly due to the high rates of deforestation and the construction of highways and dams, which have caused several environmental and social impacts affecting both fish and riverine people (Fearnside, 1999(Fearnside, , 2001Hallwass et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

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‘Taking Fishers’ Knowledge to the Lab’: An Interdisciplinary Approach to Understand Fish Trophic Relationships in the Brazilian Amazon

et al. 2021

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Trophic levels can be applied to describe the ecological role of organisms in food webs and assess changes in ecosystems. Stable isotopes analysis can assist in the understanding of trophic interactions and use of food resources by aquatic organisms. The local ecological knowledge (LEK) of fishers can be an alternative to advance understanding about fish trophic interactions and to construct aquatic food webs, especially in regions lacking research capacity. The objectives of this study are: to calculate the trophic levels of six fish species important to fishing by combining data from stable isotopes analysis and fishers’ LEK in two clear water rivers (Tapajós and Tocantins) in the Brazilian Amazon; to compare the trophic levels of these fish between the two methods (stable isotopes analysis and LEK) and the two rivers; and to develop diagrams representing the trophic webs of the main fish prey and predators based on fisher’s LEK. The fish species studied were Pescada (Plagioscion squamosissimus), Tucunaré (Cichla pinima), Piranha (Serrasalmus rhombeus), Aracu (Leporinus fasciatus), Charuto (Hemiodus unimaculatus), and Jaraqui (Semaprochilodus spp.). A total of 98 interviews and 63 samples for stable isotopes analysis were carried out in both rivers. The average fish trophic levels did not differ between the stable isotopes analysis and the LEK in the Tapajós, nor in the Tocantins Rivers. The overall trophic level of the studied fish species obtained through the LEK did not differ from data obtained through the stable isotopes analysis in both rivers, except for the Aracu in the Tapajós River. The main food items consumed by the fish according to fishers’ LEK did agree with fish diets as described in the biological literature. Fishers provided useful information on fish predators and feeding habits of endangered species, such as river dolphin and river otter. Collaboration with fishers through LEK studies can be a viable approach to produce reliable data on fish trophic ecology to improve fisheries management and species conservation in tropical freshwater environments and other regions with data limitations.

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Protected areas and frugivorous fish in tropical rivers: Small‐scale fisheries, conservation and ecosystem services

Nagl

Hallwass

Tomazoni-Silva

et al. 2021

Aquatic Conservation

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Frugivorous fish provide often conflicting ecosystem services of seed dispersal and food provisioning in tropical rivers. Fishing may reduce the size and abundance of frugivorous fish, thus affecting their potential as seed dispersers, which could affect the conservation of these fish and of floodplain forests. The goal of this study was to assess the influence of co‐managed protected areas in the form of extractive reserves (RESEX) and small‐scale fisheries on frugivorous fish in the Tapajós and Negro rivers, in the Brazilian Amazon. The study examined whether: (i) frugivorous fish are important for fisheries and selectively caught; and (ii) frugivorous fish abundance, size and fisheries catch per unit of effort are higher inside the RESEX than outside. The analyses included fisheries‐dependent data (3,753 fish landings) and independent data (12,730 sampled fish) collected in 16 fishing communities (eight for each river). In both rivers, frugivorous fish are among the 10 species caught the most and frugivorous biomass was proportionately higher in landings than in samplings, indicating fisheries selectivity towards these fishes. In both rivers, catches of frugivorous fish were higher outside the RESEX than inside. Catch per unit effort and the proportion of frugivores in the catch were higher outside the RESEX in the Tapajós River but did not vary between sites inside and outside the RESEX in the Negro River. Frugivorous fish were larger inside the RESEX in the Negro, but smaller inside the RESEX in the Tapajós. The results indicated that the ecosystem services of seed dispersal and food source provided by frugivorous fish are not in conflict in the tropical rivers studied. Therefore, these clearwater and blackwater rivers in the Brazilian Amazon show a balance between fisheries and conservation of frugivorous fish, which play an essential role in the functioning of tropical floodplain forest ecosystems.

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Fishers' Knowledge Indicates Extensive Socioecological Impacts Downstream of Proposed Dams in a Tropical River

Cited by 33 publications

References 86 publications

Fishers’ knowledge indicates temporal changes in composition and abundance of fishing resources in Amazon protected areas

Fishers’ knowledge indicates temporal changes in composition and abundance of fishing resources in Amazon protected areas

‘Taking Fishers’ Knowledge to the Lab’: An Interdisciplinary Approach to Understand Fish Trophic Relationships in the Brazilian Amazon

Protected areas and frugivorous fish in tropical rivers: Small‐scale fisheries, conservation and ecosystem services

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