Analyses of historical documents reveal past trends of exploitation of manatees (Trichechus inunguis) in the Amazon Basin (16th-19th centuries)

RESEARCH ARTICLE Analyses of historical documents reveal past trends of exploitation of manatees (Trichechus inunguis) in the Amazon Basin (16th-19th centuries) [version 1; peer review: 2 approved] Cristina Brito 1, Ana Catarina Garcia2, John Nicholls 3, Jaime Silva 2, Nina Vieira 1 1CHAM and Departamento de História, Faculdade de Ciências Sociais e Humanas, FCSH, Universidade NOVA de Lisboa, Lisboa, 1069061, Portugal 2CHAM, Faculdade de Ciências Sociais e Humanas, FCSH, Universidade NOVA de Lisboa, 1069-061 Lisboa, Universidade NOVA de Lisboa, Lisboa, 1069-061, Portugal 3Trinity Centre for Environmental Humanities, A6.003, Trinity College Dublin, 2 College Green, Dublin 2, D02 PN40, Ireland First published: 18 Aug 2025, 5:245 https://doi.org/10.12688/openreseurope.20811.1 Latest published: 18 Aug 2025, 5:245 https://doi.org/10.12688/openreseurope.20811.1 v1 Abstract The West Indian manatee (Trichechus manatus) and the Amazonian manatee (Trichechus inunguis) have been exploited by different societies from ancient times to the present. Deploying the matrix of Indigenous knowledge and uses, the hunting of manatees was at the core of European colonisation strategies of the Americas within a framework of appropriation, use, and consumption of aquatic mammals spanning the (post)colonial period. Today, both species are listed by the International Union for the Conservation of Nature and Natural Resources (IUCN) as Vulnerable, and population trends are expected to decrease in the future. While the exploitation of manatees (in particular, T. inungis) is well described in the 20th century, no overall quantitative assessments of such exploitation in the preceding centuries have been made. Here, we address this gap of knowledge through a systematic review of the literature, identification and review of documentary sources, selection and extraction of quantitative data, and contextual analysis through cross-analysis of historical documents of several types. Our quantitative estimates resulted in a total of 14.030 individuals captured, which are most probably largely underestimated. It corresponds to a biomass removal of 6.248,9 tonnes in a period of non-continuous 52 years between the 16th and the 19th centuries. Specifically, an average of c. 14.000 manatees were hunted between 1843 and 1898, comprising 91% of all captures prior Open Peer Review Approval Status 1 2 version 1 18 Aug 2025 view view Yann Hénaut , El Colegio de la Frontera Sur (ECOSUR), Quintana Roo, Mexico 1. Felipe Vander Velden, Federal University of São Carlos, São Carlos, Brazil 2. Any reports and responses or comments on the article can be found at the end of the article. Open Research Europe  Page 1 of 17 Open Research Europe 2025, 5:245 Last updated: 06 NOV 2025 to the twentieth century when another point of accelerated extraction occurred. We determined a trend of increasing captures from the 17th to the 20th centuries, for Brazil, but an important lacuna of data for the 16th century, and pre-European contact, persists. However, the results inform current and future conservation measures for the species, while also including historical, cultural, traditional, and indigenous perspectives about the use of aquatic resources. El manatí antillano (Trichechus manatus) y el manatí amazónico ( Trichechus inunguis) han sido explotados por distintas sociedadesThe West Indian manatee (Trichechus manatus) and the Amazonian manatee (Trichechus inunguis) have been exploited by different societies from ancient times to the present. Deploying the matrix of Indigenous knowledge and uses, the hunting of manatees was at the core of European colonisation strategies of the Americas within a framework of appropriation, use, and consumption of aquatic mammals spanning the (post)colonial period. Today, both species are listed by the International Union for the Conservation of Nature and Natural Resources (IUCN) as Vulnerable, and population trends are expected to decrease in the future. While the exploitation of manatees (in particular, T. inungis) is well described in the 20th century, no overall quantitative assessments of such exploitation in the preceding centuries have been made. Here, we address this gap of knowledge through a systematic review of the literature, identification and review of documentary sources, selection and extraction of quantitative data, and contextual analysis through cross-analysis of historical documents of several types. Our quantitative estimates resulted in a total of 14.030 individuals captured, which are most probably largely underestimated. It corresponds to a biomass removal of 6.248,9 tonnes in a period of non-continuous 52 years between the 16th and the 19th centuries. Specifically, an average of c. 14.000 manatees were hunted between 1843 and 1898, comprising 91% of all captures prior to the twentieth century when another point of accelerated extraction occurred. We determined a trend of increasing captures from the 17th to the 20th centuries, for Brazil, but an important lacuna of data for the 16th century, and pre-European contact, persists. However, the results inform current and future conservation measures for the species, while also including historical, cultural, traditional, and indigenous perspectives about the use of aquatic resources. Keywords Accelerated extractions; Aquatic megafauna; Brazil; Colonisation and extirpations; Marine environmental history; Marine exploitation and use of resources. Open Research Europe  Page 2 of 17 Open Research Europe 2025, 5:245 Last updated: 06 NOV 2025 Corresponding author: Cristina Brito ([email protected]) Author roles: Brito C: Conceptualization, Formal Analysis, Funding Acquisition, Investigation, Methodology, Writing – Original Draft Preparation, Writing – Review & Editing; Garcia AC: Data Curation, Investigation, Methodology, Writing – Original Draft Preparation, Writing – Review & Editing; Nicholls J: Data Curation, Formal Analysis, Investigation, Methodology, Writing – Review & Editing; Silva J: Data Curation, Formal Analysis, Methodology, Writing – Original Draft Preparation; Vieira N: Data Curation, Formal Analysis, Investigation, Methodology, Writing – Original Draft Preparation, Writing – Review & Editing Competing interests: No competing interests were disclosed. Grant information: This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 951649). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Copyright: © 2025 Brito C 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 work is properly cited. How to cite this article: Brito C, Garcia AC, Nicholls J et al. Analyses of historical documents reveal past trends of exploitation of manatees ( Trichechus inunguis) in the Amazon Basin (16th-19th centuries) [version 1; peer review: 2 approved] Open Research Europe 2025, 5:245 https://doi.org/10.12688/openreseurope.20811.1 First published: 18 Aug 2025, 5:245 https://doi.org/10.12688/openreseurope.20811.1 This article is included in the Horizon 2020 gateway. Open Research Europe  Page 3 of 17 Open Research Europe 2025, 5:245 Last updated: 06 NOV 2025 Introduction There is a certain fish, which we call marine ox, the Indians call it iguaraguá, frequent in the Captaincy of Espírito Santo [Brazil] (…); it feeds on herbs as indicated by the chewed grasses caught in the rocks bathed by mangroves. Exceeds the ox in corpulence; it is covered with hard skin, resembling the color of an elephant; it has two arms close to the breasts with which nothing; and under them teats with which their own children suck; it has a mouth entirely similar to that of an ox. It is excellent for eating, you would not know how to discern whether it should be considered as meat or rather as fish; from its fat, which is inherent in the skin and especially around the tail taken to the fire, a sauce is made, which can be compared to butter and I do not know if it will exceed it; its oil is used to spice up all foods: your whole body is full of solid and very hard bones, such that they can act as ivory1.1 There is an established history of the hunting of manatees (Trichechus spp.), or sea cows, which are known as ‘peixe-boi’ or ‘peixe-mulher’ in Portuguese, as ‘manati’ in Spanish, or as ‘goaragoa’ in old Tupi2,3. It has occurred in geographic ranges of different species’ historical presence and in different human societies that live with and exploit them. Manatee historical capture and use are reported in several regions of South America and the Caribbean basin where exploitation occurred long before the post-Columbian era4,5. In the Amazon basin, with its tributaries and adjacent marine region, manatees have been important resources for the subsistence of indigenous peoples and colonial settlements. At first, they were used for food, raw material for objects, and cultural elements in an interconnected way of living in the world2,6. Historically, they have been local food, staples, and medicinal products. Long-term capture, consumption, and use of manatees is evident from animal bones found in shell mounds, an ongoing research project on Amazonian sambaquis that has revealed the presence of manatee bones, and artefacts, since at least the middle and late Holocene7–10. Before European colonisation, manatee habitats were densely populated by many different indigenous societies, and the two sides of the Amazon were occupied, transformed by agriculture and the waters exploited both locally and regionally. The population density described by European chroniclers, such as the Jesuit father Alonso de Rojas, Diogo Nunes or Cristóbal de Acuña, about the first contacts indicates an advanced ability of the indigenous peoples to catch, produce and store food11,12. Among the storage techniques were small maize granaries, manioc flour and salt, the latter for salting fish, which indicated a certain degree of preservation capacity. The presence of turtle nurseries, many hunting and fishing methods, and well-known fishing grounds was abundantly described upon the arrival of Europeans in the American territories11–14. In particular, the entire area between the Orinoco and Amazon Rivers, which the Spaniards called Isla Guayana, was a vast landscape dominated by the Amazon tributaries, a vast dense forest, and various fauna. In the case of manatees, they were captured and used by preEuropean contact Indigenous societies and continued to be exploited throughout the centuries to come (Figure 1). For the conquest and colonisation process, access to natural resources was essential for European survival15. The European conquest of the Amazon from the 15th century, first along the shores of the river mouth by the Portuguese, rapidly moved into the hinterland following the complex watercourses of the Amazon and its multitude of tributaries14,16. This process was marked by the construction of control posts and forts during the colonial period. At the beginning of the 17th century, several European powers fought for control of the Amazon. Some of the first fortifications along the Amazon were built by the Dutch and the English, who, like the Portuguese, tried to control the region. Due to the difficulty of transporting and maintaining European domestic animals in the Amazon hinterland, the first settlers had to look for local alternatives and negotiate with local communities to obtain access to resources17,18. The consumption of certain aquatic species by Europeans, such as manatees, turtles, and several river fish, eaten dry or salted, solved the problem of animal protein needs, which in the European context was supplied by cattle. That meant, along with other supplies, access to the river’s resources such as fish, turtles, and marine mammals. In this context, contact with and observation of the practices of indigenous peoples, their daily uses of resources, and consumption were crucial to the survival of the first European settlements in the region. To gain access to the amounts needed to support newly established colonial societies, local fishing communities were subjugated through a process of appropriation of traditional knowledge and techniques and labour for hunting and fishing19,20. As the centuries passed, manatees became symbolic elements for the establishment of human interactions with the natural world from a positive perspective; manatees are established in local myths and legends and are part of Amazonian and Brazilian folklore. But there was also a negative context; manatees are now designated Vulnerable to extinction in the near future due to both the intensive exploitation in the recent past, as well as habitat degradation and human intrusion from continuing industrial development in the present.2 Manatees, among countless other aquatic megafauna species, typify the recurrent historical narrative of exploitation and unsettling of the local nature2. It is increasingly recognised that imperialism and colonization have transformed natural environments, on differing scales and intensities at a global level, and there are still significant gaps in knowledge about the patterns, causes, and consequences of these processes of appropriation, transformation, and exploitation21. This is particularly evident in the case of the 1 This is a 16th-century description of coastal manatees in Brazil by the Jesuit priest Joseph de Anchieta (1560)1. 2 Amazonian Manatee (IUCN Red List): https://www.iucnredlist.org/species/22102/43793736. Page 4 of 17 Open Research Europe 2025, 5:245 Last updated: 06 NOV 2025 Portuguese imperial context, which remains little studied and rarely included in specialised works. Compared to other imperial nations, such as the British Empire, which has been generously documented by academics22, this article seeks to populate the lacuna of Portuguese Imperial and Colonial knowledge. Our primary goals are to use historical and geographical information to establish a trajectory of past exploitation of manatees (Trichechus spp.) in South America for the 16th, 17th, 18th, and 19th centuries, and to address narratives of change in the exploitation and use of aquatic resources. This article also aims to identify and quantify manatee extractions, mainly for the Amazonian manatee (Trichechus inunguis), historically based on review of the scientific literature, reports, logbooks, treatises, and other documents. Methods We conducted a four-step approach that included a literature review, identification, and review of documentary sources, the mining of existing data (i.e. selection and extraction of quantitative data, and identification of geographic location cartographic sources). All historical sources and data collected and used in this study to estimate manatee extraction in the Amazon basin are available in online, open-access format that summarises the data sets and provides statistical information in the Supplementary Material23 (see also Table 1). Literature review A literature review of published studies about the Order Sirenia and the history of their captures was conducted, following the general approach described by Falcato and Carvalho24. We accessed and utilised major online databases (generic and multidisciplinary) such as JSTOR, SCOPUS, Web of Science, and in different search engines, such as Google Scholar, ProQuest, and B-On. The searches were based on specific keywords. The intention was to generate a global view of the state-of-the-art on the topic and to find and review studies with relevant data. The search was carried out through the Title and Keyword sections, and the parameters used were the same for many established databases and search engines; these are as follows: (manatee OR seacow OR dugong) AND (history OR “early modern”) AND (catch* OR Captur* OR harvest* OR fish*); (manatim OR “peixe-boi” OR “vaca-marinha” OR dugongo) AND (historia OR “época moderna”) AND (caça OR captur* OR pesc*); (manatí Or “vaca marina” Or dugongo) And (history Or “epoca moderna“) AND (caza OR captur* Or pesc*)ur*). A redundancy process was deployed when publications, screened titles, keywords, and abstracts were perused to ensure that each element was accessed at least twice to minimise oversights or introduced bias, thus maximising the accuracy of identified elements for inclusion and exclusion in the study. Publications written in English, Spanish, Portuguese, and French were included, both indexed peer-reviewed publications and grey literature. We focused on historical data and, consequently, publications of specific thematic criteria such as strictly ecological, behavioural, physiological, and genetic studies were excluded. Also, historical period-based exclusions were implemented to emphasize a focus on the era preceding the Industrial Revolution (c. pre-1860). A cross-check in bibliographic lists of some identified publications was also carried out. From the total of publications included in our reference program on the Order Sirenia worldwide, we identified a total of 292 studies that could be used for qualitative and quantitative analysis and historical contextualization. From these data referring to the Brazil context and for the period beginning with the colonial presence (16th century) were used. Raw data was obtained from three established studies – Antunes et al.25, Hulsman26, and Domning27. Documentary sources analysis We build on intensive research that has been carried out in recent years and on several historical sources already identified, namely those made available in the online Sea Citation Database28, which includes Portuguese and Spanish documentary sources for the early modern period, ranging from the 16th to the 19th century, and comprises reports, logbooks, descriptions, treaties, bestiaries, natural and general histories, letters, and tax Figure 1. Left: A scene of a colonial setting in a Central or South American region (18th century) showing the butchering of a manatee and possibly the boiling of its fat. Iconographic sources add information to documentary sources and indicate the relevance of an animal and aquatic resource for a given historical and cultural context. Open Access © The John Carter Brown Library at Brown University (Permalink: https://jcb.lunaimaging.com/luna/servlet/s/4io7aw). Right: Photography of manatee hunting in Lake Ayapua, the Purus River (Amazonia) of unknown date. Images and photographs are visual sources that indicate the relevance of aquatic and animal resources for a given historical and cultural context. Permission obtained from Samuel Iglesias from https://www.delcampe.net/fr/collections/. Page 5 of 17 Open Research Europe 2025, 5:245 Last updated: 06 NOV 2025 Table 1. Number of extracted individual manatees and biomass. See, for detailed data and sources: Vieira, N., Brito, C., & Nicholls, J. (2024). Extraction Amazonian Manatee (Trichechus inunguis), 1533–1898 [Data set]. Zenodo. https://doi.org/10.5281/zenodo.15739198. Year Ave_individualCount MAX Number of manatees MIN Number of manatees organismQuantity [biomass in ton] 1533 2 2,0 2,0 1,1 1606 3 3,9 1,7 1,5 1608 3 3,9 1,7 1,5 1614 250 250,0 250,0 137,5 1670 21 28,6 12,3 10,5 1724 4 5,3 2,3 1,8 1780 1 1,2 0,5 0,45 1785 927 1295,0 559,2 417,15 1793 1 1,3 0,6 0,45 1843 51 70,7 30,5 22,95 1846 74 103,9 44,9 33,3 1853 2250 3141,6 1356,6 1012,462455 1855 308 429,3 185,4 138,6 1856 411 573,6 247,7 184,95 1857 239 332,1 143,4 107,55 1858 230 321,5 138,8 103,6029456 1859 169 236,4 102,1 76,07106011 1860 1564 2183,9 943,1 703,6793586 1861 151 210,9 91,1 67,92893989 1862 227 316,4 136,6 101,9463965 1863 188 262,8 113,5 84,67273475 1864 46 63,8 27,6 20,55883672 1865 133 185,2 80,0 59,85 1867 178,7 249,0 107,5 80,40883672 1869 110 153,6 66,3 49,5 1870 170 237,3 102,5 76,5 1871 455 635,9 274,6 204,7944752 1872 359 495,1 213,8 161,6889447 1873 76 106,3 45,9 34,2 1876 14,0 14,0 13,4 4,35 1877 208 291,2 125,8 93,6 1878 133 185,6 80,1 59,85 1879 148 204,7 88,4 66,6 1880 205 286,3 123,6 92,25 Page 6 of 17 Open Research Europe 2025, 5:245 Last updated: 06 NOV 2025 3 Digital library for the project and related data accessible through https:// resgate.bn.br. Year Ave_individualCount MAX Number of manatees MIN Number of manatees organismQuantity [biomass in ton] 1881 1271 1770,9 764,7 571,884532 1882 607 760,7 328,5 193,6628 1883 78 107,4 46,4 23,96546053 1884 461 644,4 278,3 207,5891447 1885 225 313,8 135,5 101,25 1886 323 451,9 195,1 145,35 1887 234 326,4 141,0 105,3 1888 411 573,9 247,8 184,95 1889 180 250,7 108,3 81 1890 76 106,2 45,9 34,2 1891 136 189,2 81,7 61,2 1892 185 258,9 111,8 83,25 1893 184 256,5 110,8 82,8 1894 133 186,0 80,3 59,85 1895 146 203,5 87,9 65,7 1896 90 126,1 54,4 40,5 1897 111 155,4 67,1 49,95 1898 33 46,6 20,1 14,85 documents. A brief review of Dutch sources was also carried out, since the Dutch occupied territories in north-eastern Brazil between 1630 and 165429 and traded manatee products in the South Atlantic30. In total, around 100 historical documentary sources of different typologies were consulted, from which sixteen historical sources were analysed which included letters and descriptions of nature and economic and scientific reports1,26,31–43. Several additional documents from the digital library Projeto RESGATE3 were also analysed and included, namely from the collections ‘Rio Negro’, ‘Pará’ and ‘Geral Brasil’. Sources refer to extractions in the Amazon basin, from its mouth and adjacent waters to the hinterland, leading to our information that refers to the Amazonian manatee (T. inunguis) even though extractions of West Indian manatees (T. manatus) (n = 4) were also recorded in coastal areas of Brazil and Suriname. Historical documentation can provide information on the harvesting of living marine resources, even for periods when there was no systematic recording of extractions or statistical reports. In many cases, the information is of a qualitative character, which allows us to infer cultural contexts in which the extractions took place, the techniques used, and the people involved, as well as to understand the importance of the animals and the use of their products. In other cases, it is possible to extract quantitative data on the number of animals hunted, even if this information is sometimes scattered. Data are varied in terms of their levels of description and of units used to quantify amounts and products. Meat (dry, salted, or fresh) was generally given in kilograms or equivalent; fat and butter (the so-called ‘mixira’) were packaged in barrels, jars, and cans (all equivalent to each other in terms of content). On occasion, hides were also included, since they were a product to be exported. When available, data with information on the geographic location of captures was considered. Mining data and quantification of extractions To convert the given amounts of manatee products into the numbers of hunted individuals, we followed the methodology used by Domning27 and cross-checked it with other studies, e.g. Whitehead44 and the historical sources available, particularly with Ferreira34. An ‘arroba’ (an old Portuguese measure of weight) of meat is equivalent to 15 kg; based on the references mentioned above, one jar (‘pote’) corresponds to c. 20–30 kg, and we use the medium value of 25 kg; one can (‘lata’) is equivalent to 22 kg. We used a conversion rate of 76 kg–176 kg of transformed product corresponding to one hunted manatee. Page 7 of 17 Open Research Europe 2025, 5:245 Last updated: 06 NOV 2025 Ferreira34 states that for the years 1785–1786 a total of 1500 manatees were hunted and provides the number of products obtained from them. Domning27 states minimum and maximum values for the mass (in kg) corresponding to one animal, which we also use to indicate a confidence interval (or error). We use a conversion factor of 20,34 kg as the average hide weight of commercially hunted manatees, according to Antunes et al.25. Based on these conversion rates, we obtained minimum and maximum values for extracted manatees for the region and for the period in question. We obtained a total of 131 data entries in our database4 that were classified under a traffic light code system for the level of certainty of the data obtained. The red entries corresponding to unreliable or unverifiable quantitative information were excluded and only the orange and green data were included, resulting in 52 separate annual records during the period between 1533 and 1898. Identification of geographic locations From the studies and historical sources reviewed, it was possible to determine approximate geographical locations either of the places of capture or the places of trading. When names of villages or broad areas are given, mapping these places offers a spatial visualisation of the extraction practice that can also be combined with other fishing practices or geopolitical settlement information for colonial Brazil. In the 16th century Portuguese and Castilians invested in the settlement of the Amazon, first building mission villages, working as indoctrination centers for the natives, under Capuchin, Mercedarian Missionary Sisters, Franciscan, Carmelite, and Jesuit religious orders. In many cases, these mission villages, located precisely in the same places as indigenous societies, settled at the mouths of the Amazon tributaries, where indigenous fishing grounds were located45. Subsequently, these locations were considered strategic for settlement under the Portuguese crown, leading to the construction of forts and villages under the Portuguese colonial administration15,46,47. For strategic reasons, the most important Portuguese settlements were located at the confluences of the watercourses, which was also where many of the royal fishing grounds were established47. In fact, identifying possible locations of the first Portuguese settlements and fortifications could indicate possible capture areas, as well as indicate how colonists migrated inland, gaining ground in the Amazon territory46,48. The need to provide protein, fat and fuel for people who were part of these newly formed colonial communities - crown officials, army, officers engaged in public and civil works, religious missions, members of the expeditions and those determining territorial boundaries - justified the establishment of royal fishing grounds, most on prior indigenous fishing grounds17,19. With settlements, people, and resources under Portuguese control, former indigenous fishermen worked for the Portuguese crown and under the auspices of royal officials15,49. Although the distribution of the fishing grounds managed by the Portuguese crown, the so-called royal fishing grounds of the Amazon, are not accurately located, understanding of the capture areas enables insights into the distribution of the capture zones. To reconstitute this geographical distribution, information related to the location of forts and settlements was compiled, considering the chronology of edification. These location data for the royal fishing grounds of the colonial period were gathered by recognising that many had been appropriate indigenous fishing grounds prior to the arrival of the Portuguese, and some of them are still in use today17,19,50,51. Location-extraction datasets were considered and included in the georeferencing elements of the database. Extraction records for undefined areas, such as the Amazon province, were mapped within an extended area corresponding to the region. Results Here we focus on preindustrial captures and the long-term effect of continued extractions of manatees by colonial Europeans in tropical regions, up to end of the 19th century. (…) at eight o’clock we arrived at the harbour of the said town [village and fortress of Obidos, Brazil], which is thirty-two leagues away from the upper mouth of the Surubiú River, from where we set sail on the 21st: soon afterwards, H.E. disembarked, having the pleasure of seeing on the beach three manatees, which had been caught that morning (...) from there he went to examine the pottery and warehouses of the same village [of Santarém], then to see its beaches, and at the house of the administrator of the royal fishing grounds to observe a live manatee that was kept there, as well as two dead ones that the fishermen from the town had brought that night (...)52.5 Extractions and biomass removal Our quantitative estimate resulted in a total of 14.030 (min. 8.301 – max. 19.220) manatees extracted in a total of 52 years during the 16th (n=1), 17th (n = 4), 18th (n = 4), and 19th (n=43) centuries; ‘n’ is the number of years for which quantitative data is available. These values represent the period between 1533 and 1793, and almost continuously from 1843 to 1898 (Figure 2 and Table 1). A total of 12.818 hunted manatees are indicated for the period between 1843 and 1898, comprising 91% of the captures. The oscillations observed over the centuries can be assumed as a global trend that is consistent with Domning27 and Antunes et al.25, justified by the inconsistency of historical data, and that is also the case for other species of marine mammals, such as cetaceans53. In addition, we estimated the removal of manatee biomass (Trichechus spp.) for the study period (1533–1898) as a first attempt to develop repeatable and 4 Vieira N, Brito C, Nicholls J. Extraction Amazonian Manatee (Trichechus inunguis), 1533-1898 [Data set]. 2024. Zenodo. https://doi.org/10.5281/ zenodo.15739198. In this open access Supporting Documentation and Database, we included all historical sources and data collected and used in this study to estimate manatee extraction in the Amazon basin. It summarises the data sets, provides statistical information and the supporting documentation; available following the Darwin Core schema, ensuring the inclusion of relevant data fields. Data may be openly shared, distributed, or used under Creative Commons licensing provisions CCBY 4.0. 5 A description of the observation of manatees, alive and dead in 18th-century Brazil (1784)52. Page 8 of 17 Open Research Europe 2025, 5:245 Last updated: 06 NOV 2025 reliable methods to estimate live weight biomass from historical data. Based on our estimates of individuals captured and derived weight for the species at 550 kg for T. manatus54 and at 450 kg for T. inunguis54–57, we obtained a total of 6.248,9 tons (Figure 3). Historical trends in abundance and geographic distribution Our comparison of multi centuries extractions shows a trend of increasing captures from the 17th to the 20th centuries; for the 16th century one single source was found. To better understand the intensity and geographical areas where manatees were taken, information was provided on the European colonisation of the Amazon region. The geographical extent of the exploited manatees ranged from the Brazilian coast (from Fort São Joaquim do Rio Branco in the north and the Royal Fort of Príncipe da Beira in the south), but mainly around the Amazon basin and delta and the various tributaries of the Amazon upstream to Tabatinga near the Peruvian border, a conflict zone with Castilian settlements. The two species occur in this geographical area, with a possible overlap in the nearshore waters of the Amazon estuary. In mapping extractions of manatee locations for the total analysis period, the middle Amazon was found to be the primary region where manatee products were traded (Figure 4). This region is where the bulk of captures occurred, and this is a good indicator that the dominant species of manatee that was hunted is T. inunguis. The conquest movement also shows locations where natural resources, including manatees, were needed the most. Through our mapping of the settlements, we recognise that military control posts penetrated further inland, and the occupation of the territory became more intense throughout the 18th century. As previously identified, the so-called royal fishing grounds, under Portuguese domain, were in many cases former indigenous fishing grounds. Many of the actual fishing grounds continued to be used, and even today names such as Pesqueiro dos Manatins (manatee fishing grounds) and Pesqueiros das Tartarugas (turtle fishing grounds) are still used. After the Portuguese administration took over, the fishing grounds began to provide these communities with protein and enabled them to generate surpluses for export through increasingly intensive fishing. The approximate geographical allocation of manatee catching or export areas along the Amazon corresponds in many cases to important military zones such as Belém do Pará and Manaus (Figure 5). Observation of the geographical location of the fishing grounds in their vicinity indicates that there is a correlation between the three elements of fortifications, fishing grounds, and manatee catches. From the geographical distribution, we can see that captures follow the process of occupying the hinterland alongside the establishment of Portuguese military positions. Discussion Pre-industrialization extractions of Amazonian manatees Continued exploitation of aquatic animals led to continued use and demand for key species of interest, structured around the mindset and ideology of European property and rights of exploitation, even if the system was built upon local practices and knowledge about the aquatic resource and their ecosystems. Manatees were historically used locally as food, medicine, and mythical-religious objects by the native peoples of the Amazon region. Colonisation across the South Atlantic led to the development of regional and transoceanic networks built to feed European settlers and their multiple demands within colonial systems and dynamics. With the opening of overseas territories to European societies because of early modern Figure 2. Documented years (n=52) of manatee extractions (Trichechus spp.): 1533 to 1898. Data are for the Amazon basin and adjacent waters, except for 1533 (southern coast of Brazil), 1608 and 1670 (Suriname) (see supplementary material online). The average number of manatees extracted are indicated by the blue bars, showing the variation of maximum and minimum estimates. Page 9 of 17 Open Research Europe 2025, 5:245 Last updated: 06 NOV 2025 Yes Is the work clearly and cogently presented? Yes Is the argument persuasive and supported by evidence? Yes If any, are all the source data and materials underlying the results available? Yes Does the research article contribute to the cultural, historical, social understanding of the field? Yes Competing Interests: No competing interests were disclosed. Reviewer Expertise: Amazonian Ethnology; Anthropology of Human-Animal Relations I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard. Reviewer Report16 September 2025 https://doi.org/10.21956/openreseurope.22516.r58693 © 2025 Hénaut Y. This is an open access peer review report distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Yann Hénaut El Colegio de la Frontera Sur (ECOSUR), Quintana Roo, Mexico This work presents highly original data on the history of Amazonian manatee exploitation. It provides new and very interesting information on this subject, particularly with regard to periods prior to the present day (before the nineteenth century) and how this historical exploitation has impacted on the current conservation status of the species. Overall, the article seems well written, but as I am not a native English speaker, I cannot judge the details of the language. The methodology also seems comprehensive to me, although I am not a specialist in this type of study. I believe this work deserves to be indexed and will shed new light on our history in relation to the conservation of manatees. Is the work original in terms of material and argument? Open Research Europe  Page 16 of 17 Open Research Europe 2025, 5:245 Last updated: 06 NOV 2025 Yes Does it sufficiently engage with relevant methodologies and secondary literature on the topic? Yes Is the work clearly and cogently presented? Yes Is the argument persuasive and supported by evidence? Yes If any, are all the source data and materials underlying the results available? Yes Does the research article contribute to the cultural, historical, social understanding of the field? Yes Competing Interests: No competing interests were disclosed. Reviewer Expertise: Animal behavior I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard. Open Research Europe  Page 17 of 17 Open Research Europe 2025, 5:245 Last updated: 06 NOV 2025