Management of Pirarucu (Arapaima gigas, Teleostei, Osteoglossidae) in Sustainable Use Units as a proposal for the restoration of aquatic ecosystems

Abstract: Sustainable Use Units have been carrying out sustainable management since the 1990s in the State of Amazonas, leading to research on the influence of management plans on restoring ecosystems. We developed an integrative review and analyzed official documents, data from the Brazilian government and information obtained from fishermen on the Unini River Extractive Reserve. The review articles were analyzed qualitatively, and a X2 test was used to verify differences in the distribution of proportions of pirarucu between the years after implementing the management. The management plan was the most cited as a solution to the environmental, social, and economic problems identified in the ecosystems. The data showed an increase in the numbers of pirarucu both in State of Amazonas and in the Unini River Reserve, reinforcing the perception of the community and fishermen. This suggests that when management plans are developed with the involvement of the local community, they present potential to restore ecosystems.


Introduction
In Brazil, the management of Conservation Units is developed in dialogue with the conservation and management of the ichthyofauna, as it includes social participation in the administration of protected areas, in the knowledge management and in the relationship between conservation and socioeconomic development (Polaz & Ribeiro, 2017). With the implementation of extractive reserves, one of the types of Conservation Unit Categories in Brazil, defined as the area used by traditional extractive populations, whose subsistence is based on extractivism, it is possible to increase the control of natural resources by local communities (Isaac-Nahum, 2006). A similar situation occurs in Sustainable Use Units (SUU), Indigenous Lands, or protected areas that have management permission through fishing agreements.
SUU, such as extractive reserves, originated as a form of criticism of the increasing deforestation occurring in Amazonia, with the purpose of covering different ecosystems or microenvironments in its territory and allowing the interaction between ecosystems in their multiple dimensions (Cunha, 2001).
An example of this is the case of the Amazon lowlands. Although more than half of the flooded habitats can provide feeding and breeding conditions for pirarucu (Arapaima gigas), they were intensely deforested (Castello et al., 2011;Renó et al., 2011), further intensifying the decline of fisheries in most of the Amazon (Castello & Stewart, 2010;Castello et al., 2013a). Deforestation with an impact on fishing is more typical in areas outside biological or extractive reserves (Castello et al., 2013b), justifying the creation of SUU.
The fishing resources are renewable, although also finite. A fishing extraction above a certain point may affect fish stocks and populations commercially and even biologically. This impact may increase even more with the occurrence of extreme phenomena such as large droughts (Oviedo & Crossa, 2013), climate change, alteration of river flows, sedimentation of rivers, which often result from human activities. This can affect not only the O plano de manejo foi o mais citado como solução aos problemas ambientais, sociais e econômicos identificados nos ecossistemas. Os dados mostraram aumento nos quantitativos de pirarucu tanto para o Estado do Amazonas como na Reserva Extrativista do rio Unini, em concordância com a percepção da comunidade e pescadores, sugerindo que planos de manejo, quando elaborados com o envolvimento da comunidade local, apresentam potencial na restauração de ecossistemas.
Palavras-chave: populações de campos; florestas e águas; ambientes de pesca; planejamento ambiental. and what are the existing gaps. We use the information available in the literature about the pirarucu management plan implemented since 2011 in the Unini River Extractive Reserve, as a case study.

Material and Methods
In order to search for articles, we used the following descriptors and their combinations in Portuguese and English: management plan; extractive reserve; aquatic organisms; ecosystem restoration; ecosystem evaluation; Unini River; Pirarucu; Arapaima. We used the database ScienceDirect® and the Google Scholar tool in the advanced search mode to have access to other databases.
The criteria for including the articles were: published in Portuguese, English or Spanish; articles in full that portrayed the theme of the review, and articles published and indexed at those databases in the last fifteen years. Articles that exclusively addressed marine or coastal environments or agroforestry management plans were excluded. The analysis of the articles was descriptive, allowing the observation, counting, description and classification of the data, in order to organize the knowledge produced on the topic.
For the case study, we analyzed the documents, data from the Arapaima gigas species that counts in the period from 2012 to 2017, the extractive fishery data (1994 to 2011) made available by Chico Mendes Institute for Biodiversity Conservation (ICMBio), and the information obtained in the field at the dry season in October 2018 during the management of the fishery with the fishermen of the communities of the River Unini Extractive Reserve.
To test whether there was a difference in the distribution of the proportion of young (budecos) and adult pirarucus from 2012 to 2017 obtained by the counting method adopted for the species (Castello, 2004), we chose the X 2 (chi-square) test, with a level of confidence of 5%, accepting that each years' groups are independent and the items of each group are counted randomly. We used the Epiinfo TM software version 1.4.3.

Literature review
In the search using the keywords described in the methodology we obtained 59 articles available online, and only 12 directly presented the main environmental causes and their consequences to the continental aquatic ecosystems, as well as the use of management as a possible solution for the conservation and recovery of aquatic ecosystems (Table 1).
Among all the causes, the most cited are climate change, increased fishing effort and alteration in water resources. The environmental consequences are wide and vary according to the causes and ecosystems under analysis. Among the solutions, management was the most cited, and it could be conservationist, participatory, active or passive, proactive or reactive. Fishing agreements was also highlighted.
The articles also emphasized the importance of ecosystem monitoring as a way of predicting future scenarios, possible ecological consequences, determining how management practices should be implemented, as well as providing information on biology, population parameters and the effects of exploitation. They also pointed to the possibility of using modeling as a tool to help in the restoration (Table 1).

Case study: management of pirarucu
The shortage of vegetable resources, intensified by deforestation in the Amazonia biome, made fishing -which was previously secondary -a main source of food and income, leading to overexploitation of fish species. The piscivorous and carnivorous groups are the preferred targets of many commercial fisheries; however, these species of higher trophic levels and fairly large body sizes present greater vulnerability, and their recovery is not an easy task (Isaac et al., 2012).
This overexploitation is observed in the pirarucu extractive fishery between 1994 and 1995 in Brazil (>3,400 t/year) and in the State of Amazonas (2,122.00 t/year), but also in the impact of the following years, from 1996 to 2004, with a variation of 0.208 t/year to 0.71 t/year ( Figure 1A). However, with the creation of SUU with management plans ( The Unini River Extractive Reserve is one of the twelve SUUs with management plan. It encompasses approximately 99% of the Unini River basin (FVA, 2011), and was zoned into three sectors, of which the second is currently destined Table 1. Summary of results in identifying the main environmental causes and consequences in aquatic ecosystems and solutions for recovery. 9. Reference: Erwin (2009) Place of coverage: Aquatic ecosystems in general Environmental Causes and Consequences: Global climate change coupled with a host of other pressures may result in increased spread of alien species and, consequently, greater pressure on the river basins. Generalized stress and spatial deviation can wipe out swamp areas, threatening the survival of species, the health of the natural systems, and the integrity of ecosystems. Solutions: Use of integrated modeling in the restoration of wetlands, in the adaptive management, and in plans at the level of mega river basins. The gaps to be overcome include the little discussion on wetland restoration and climate change, lack of monitoring, which is essential for the ecosystem management, as it intends to detect long-term changes in the ecosystem, provides insights on possible ecological consequences, and helps decision-makers to determine how management practices should be implemented. 10. Reference: Palmer et al. (2008) Place of coverage: Aquatic ecosystems in general Environmental Causes and Consequences: Drastic changes in flow, increased demand for water related to economic and population growth, which may have effects even be greater than climate change on the water available to many rivers, leading to biodiversity loss. Solutions: Specific actions of restoration, rehabilitation, proactive and active management to improve the resilience of riparian ecosystems and minimize impacts. 11. Reference: Bengtsson et al. (2003) Place of coverage: Aquatic ecosystems in general Environmental Causes and Consequences: Ecosystems are subject to both natural and man-induced disturbances at various spatial and temporal scales. Solutions: Recognize that not just nature, but humans are also part of the ecosystem, so reserves cannot be static, but are part of the management of the adaptive landscape. Although reserves are crucial for the short-term conservation of species and habitats, some of them have not incorporated long term and large-scale dynamics of ecosystems as parts of dynamic landscapes and it is necessary to reconsider how reserves are designed and managed in areas increasingly dominated by humans. 12. Reference: Jungwirth et al. (2002) Place of coverage: Aquatic ecosystems in general Environmental Causes and Consequences: The intensive use and alteration of riverside landscapes by humans have led to drastic reductions in functional flood plains, loss of typical floodplain elements, alteration of hydrological and temperature regimes, impacting the reduction of biodiversity, spatial-temporal heterogeneity, functional processes and the diversity, density and biomass of species. Solutions: To have a political objective of maintaining or restoring the ecological integrity of the riverside landscapes; establish priorities of what must be preserved, mitigated and restored according to the ecological state of the water resource; incorporate new visions of the management of the floodplain that meet the needs of both humans and the natural systems. Use of hydrological, morphological and ecological conditions models to assist in the restoration of complex floodplain systems, as they predict and evaluate the effectiveness of restoration measures. The identified shortcomings are the lack of detailed information on functional relationships and processes in the landscape and catchment scale, which make it difficult to assess their ecological status.  for participatory fishing management. Between the years 2012 and 2017, 75 types of environments of the lakes, ressaca 1 , paranã 2 and furo 3 were mapped in sector 2 by the group of fishermen from the 10 communities present along the Unini River.
The creation of this Resex occurred due to illegal fishing, sport fishing done with small aircrafts without adequate monitoring, deforestation, uncontrolled fires, conflicts between communities regarding the overlapping of resource use (ICMBio, 2018), as well as the extraction of sand by mining companies since 2004 (ICMBio, 2014).
Since the creation of this SUU, in the perception of fishermen, residents and reports of the Fundação Vitória Amazônica (FVA), there has been a decrease in the number of socio-environmental conflicts in the lower Negro River, and a considerable increase in fish stocks. The pirarucu have been 1 Networks of water accumulation basins. 2 Lakes which have direct connections to the river through canals. 3 Connects a lake to a river or another lake. sighted in various places, even in the ports of their communities.
The data shows a variation in the number of days in the field (maximum 14 days and minimum of seven days) and in the number of fishing lakes (maximum 70 and minimum 43) during the counting of the species, which seems to reflect on the number of counted specimens (Figure 2). However, the chi-square test showed significant differences (p<0.05) between the annual numbers of pirarucus counted in the year 2013 when compared to the other years ( Table 2). The year 2013 is one of the years with the highest numbers of analyzed environments and a high number of days in the field, but the years 2016 and 2017 stood out in comparison with 2013 and presented higher values for both young and adult fish (Table 2).
In the participatory management plan, community surveillance is one of the activities planned with the objective of avoiding predatory exploitation and identifying who does not follow the rules established in the management plan. At Resex,  The chi-square test (X 2 ) and p values of the observed quantitative values of young (<1.5 cm length) and adults (>1.5 cm length) in the lakes, ressacas and paranã in sector 2 of the Unini River Resex, from 2012 to 2017.
there were records of emigration of former residents because they did not adapt to the surveillance and because they illegally exploited pirarucu and chelonians (Caldenhof, 2013), showing the importance of the activity for the very community which uses the resources.

Discussion
The different types of management were mentioned as some of the most plausible solutions, as strategies to confront species extinction, mitigate processes and minimize environmental crisis (Mateus et al., 2017) in the elaboration of conservation and preservation measures (Oviedo & Crossa, 2013). Moreover, as a possibility of dealing with climate change (Lawler, 2009), improving the resilience of riparian ecosystems, minimizing impacts (Palmer et al., 2008), and contributing to the recovery of the complex, structured and spatial units -if the interdependent relationship is maintained between the actors and factors, whether they are biotic, physical or socioeconomic (Berkes, 2009). This situation is observed by the fishermen, who know the behavior of the species well, in relation to the increase of the fish stock. Hanazaki (2003) emphasizes the importance of considering local ecological knowledge, or traditional ecological, or ethnoecological knowledge. They are orally passed by these human populations living in or close to the ecosystems to be managed, and have important connections for the management based on local participation and sustainability principles.
When the management takes place in the environment as a whole, maintaining the ecosystemic focus ensures the conservation of the landscape with its components, serving as an effective means of conservation. We suggest that this situation is taking place in the Unini River basin with the creation of the Resex and the use of resource management. Although it is not restricted to the management of the ecosystem, this situation is also observed in the management of the pirarucu, because, according to Figueiredo (2013), it brings with it a power of conservation and organization of the use of several resources with gain for the conservation of the landscape and its components.
It was also validated by the authors Campos-Silva et al. (2019), who demonstrated in their studies along the Juruá River in the western Brazilian Amazon a recovery pattern of the pirarucu population through the use of management programs carried out by the ribeirinha community. This reaffirmed the data found in previous studies and Unini River Resex, that community-based shared management is a powerful tool for biodiversity conservation and local livelihoods.
Authors such as Jungwirth et al. (2002) recall that most of the world's 79 major floodplain ecosystems have been altered precisely by human activities, and restoring them requires knowledge that includes geomorphology, hydrology, landscape ecology, landscape planning, hydraulic engineering, aquatic and terrestrial ecology. Consequently, also requires the formation of interdisciplinary teams, which must be present in all phases of the planning, implementation, and evaluation process.
Restoration is not always possible, due to lack of logistical, financial, and human resources, availability of monitoring data and teams formed for this purpose in the country. This induces the reflection that, instead of trying to recreate ecosystems with properties characteristic of the past, the ecosystem's dynamic nature and the irreversibility of some changes that have occurred must be recognized.
However, from the possibility of using the traditional ecological knowledge in the elaboration and execution of management plans in these SUU, this instrument becomes a viable option not only for the conservation, but also for the recovery of ecosystems. These ecosystems must not be transformed, however, into island reserves, or an intensive management landscape administered to meet human goals disconnected from the natural process scales (Bengtsson et al., 2003).
Encompassing approximately 99% of the Unini River basin, the Unini Resex has allowed zoning almost all of its extension and a management shared by all the communities that live along the riverbank, meeting the proposal of using managements based on hydrographic basins. These have been identified as the most appropriate spatial management units in various parts of the world (Erwin, 2009). Thus, Unini Resex provides a unique opportunity to establish an integrated model of management for protected areas (FVA, 2011) and, together with two other Conservation Units (Jaú National Park and Amanã Sustainable Development Reserve), forms a network of protected areas with several ecosystems rather than isolated islands.
The oscillation observed in relation to the number of environments where the counting was performed suggests the perspective of a management plan that is not only participative, but also adaptive. According to Berkes (2009), the adaptive management plan allows integrating uncertainty into management strategies, emphasizing practices that encourage resilience, responding to and managing ecosystem feedbacks, rather than blocking them, and seeks to avoid ecological thresholds in scales that threaten the existence of social and economic activities.
This environmental oscillation, as observed in the field, is related to the richness of the environments and the complexity of the types of existing lakes (central, boca franca 4 ), paranã, ressacas and holes, in a highly sinuous river like the Unini.
The pirarucu may exhibit sedentary behavior when the environment is in equilibrium (Oviedo & Crossa, 2013). This seems to reflect positively in the number of young and adult populations observed in the years 2016 and 2017. Another factor which influences this number is the carrying out of communitarian inspection actions by trained groups of fishermen from the different communities, inhibiting illegal fishing.
From the results, it is understood that even in a changed ecosystem, when it is transformed into a SUU, natural resources which were previously open to free access are now monitored, and their exploitation is guided by an instrument, the management plan. This situation was envisaged by Campos-Silva & Peres (2016) when comparing Arapaima fish stocks from managed and unmanaged areas on the Juruá River in the State of Amazonas, Brazil, finding a larger population of the species in community managed areas.
This instrument, initiated in SUU in the State of Amazonas, with its participative nature that avoids severe environmental modifications, becomes more efficient in the maintenance, allowing sustainable resource use (McGrath & Castello, 2015;Campos-Silva et al., 2019). Besides, it avoids the removal of key species, which is one of the major impacts on aquatic ecosystems. However, in Brazil, there is a need to strengthen these policies, which is visible for the absence of data and research that allow a better evaluation of their effectiveness.