**5. Social and economic effects of climate changes and dams on amazonian fisheries**

Fisheries are very important activity worldwide. Gross revenues from marine capture fish‐ eries worldwide are estimated between US\$ 80 billion and 85 billion annualy [49]. However, some authors stated that the global marine fisheries are underperforming economically due to overfishing, pollution and habitat degradation [50]. As is the case in many regions of the world, fish are a key source of animal protein, essential amino acids and minerals, mainly for low-income population who live in the Amazon basin [3, 5, 6]. A recent paper examines if marine fisheries and aquaculture can supply fish demand for a growing human popula‐ tion, taking into account climate change [51]. The authors claim that an effective manage‐ ment of fisheries is necessary to assure sustainability for world fish stocks. The authors also called for a reduction in the amount of wild fish employed to produce animal feed.

In general, Brazilian fish production followed the world tendency, with mean rates of growth of 2.48% and 10.82%, for fishing and aquaculture, respectively [52]. Analyzing just Amazonas State, the main producer of fish exclusively from freshwater, we can see that the state follows the same trend of the region, for the last ten years. On average, the Amazonas State contributed 29% of the region's fisheries production.

A closer analysis of the data shed some light on the impacts of environmental changes, as a result of climate changes or dams, on fisheries and its consequences for well being. Figure 5 shows the Amazonas state Gross Domestic Product (GDP) per capita and an index of fish production growth, for the period between 1992 and 2010, taking 1992 as base year.

impacts on recruitment success. An analysis on the influence of the mean annual water level (m), the amplitude (maximum water level of the river in a given year; m) and the flood du‐ ration (number of days above 3.5 m; yearly total and for each season; summer and autumn were considered together) on the recruitment of *Prochilodus scrofa* for the fishery conducted at the Itaipu Reservoir and observed that flood duration is more important than flooding

Table 3 summarizes the effects of global warming, sea level rise and dams on freshwater Amazonian fish, taking into account our level of knowledge. Fish faced with a changing en‐ vironment must adapt, migrate or perish [19]. In addition to the high level of uncertainty at the species level, some evidence is available to predict that the resulting stress of a tempera‐ ture increase will affect fauna as a whole, including fish. The effects of the higher energy de‐ mand to compensate the stress would start at the physiological level and would include size reduction and reproductive failure. This evolution affects the community structure when the dominant species has more adaptive capacity. Therefore, another possible effect of climate change is the loss of biodiversity through the extinction of specialized or endemic fish spe‐ cies [48]. This pattern of environmental change inducing effects will initiate from a rise in

**5. Social and economic effects of climate changes and dams on**

called for a reduction in the amount of wild fish employed to produce animal feed.

production growth, for the period between 1992 and 2010, taking 1992 as base year.

State contributed 29% of the region's fisheries production.

In general, Brazilian fish production followed the world tendency, with mean rates of growth of 2.48% and 10.82%, for fishing and aquaculture, respectively [52]. Analyzing just Amazonas State, the main producer of fish exclusively from freshwater, we can see that the state follows the same trend of the region, for the last ten years. On average, the Amazonas

A closer analysis of the data shed some light on the impacts of environmental changes, as a result of climate changes or dams, on fisheries and its consequences for well being. Figure 5 shows the Amazonas state Gross Domestic Product (GDP) per capita and an index of fish

Fisheries are very important activity worldwide. Gross revenues from marine capture fish‐ eries worldwide are estimated between US\$ 80 billion and 85 billion annualy [49]. However, some authors stated that the global marine fisheries are underperforming economically due to overfishing, pollution and habitat degradation [50]. As is the case in many regions of the world, fish are a key source of animal protein, essential amino acids and minerals, mainly for low-income population who live in the Amazon basin [3, 5, 6]. A recent paper examines if marine fisheries and aquaculture can supply fish demand for a growing human popula‐ tion, taking into account climate change [51]. The authors claim that an effective manage‐ ment of fisheries is necessary to assure sustainability for world fish stocks. The authors also

amplitude [48].

186 New Advances and Contributions to Fish Biology

sea level and the introduction of dams.

**amazonian fisheries**


**Table 3.** The potential impacts of global climate change and dams and their effects on freshwater Amazonian fish

much less intensity. It is clear from the graph that while GDP per capita presented a strong

The Potential Impacts of Global Climatic Changes and Dams on Amazonian Fish and Their Fisheries

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189

What relationships do these trends have with global warming? It is clear that fish produc‐ tion does not drive GDP growth, so global climate change is not likely to have much impact on the GDP of Amazonas through the impact of global change on fisheries. This is not to imply that there would not be critically important impacts through other sectors of the econ‐ omy. Of course, impacts on fisheries would have a large impact on the income of those par‐ ticipating in the commercial fishing industry, and it could have a significant impact on the GDP of small cities in Amazonia (5 to 10 thousand inhabitants) that do not have alternative sources of income. This is particular true for small cities that are sufficiently close to Manaus

It should be noted that GDP is a measure of market output, not economic benefits and there are a number of ways in which fisheries impact social welfare, both within the ur‐ ban/industrial area and within the rural communities. For example, the output of subsis‐ tence fisheries is explicitly excluded from the measure of GDP because the output is not traded in formal markets. Clearly, small communities will suffer immensely if fisheries are highly impacted by climate change. Moreover, Amazonas has a fish culture, as op‐ posed to the beef culture of the rest of Brazil. As Table I indicates, fish consumption is extraordinarily high, even in urban centers. If fish become scarcer and more expensive, the welfare of the urban centers will be diminished as they are forced to substitute meat

The social welfare impacts of global climate change induced impacts on fisheries are diffi‐ cult to calculate. The reason for this is that the direct impacts on fisheries may change eco‐ nomic behavior, which could then lead to a series of indirect impacts that could compound the impacts of climate change. These reactions could occur between urban and rural com‐

If the impacts of global climate change on fisheries reduce the quality of life of small com‐ munities, it could spur additional migration from the small communities to the urban cen‐ ters. This would increase the urban externalities associated with population increases as a whole, and those associated with immigration of a group of people without training to par‐ ticipate in the service or industrial sectors of the urban center. Moreover, the introduction of more people with a high preference for fish consumption into the urban center will increase the urban demand for fish, putting more pressure on the fisheries near the urban centers,

People that remain in small communities will continue to be negatively impacted by the de‐ creased fish populations because of the impacts of global climate change. This could lead to several negative impacts. First, they may react to the change by fishing more intensively to try to compensate for the decline in populations. This will further stress the populations that are already stressed by global climate change. Second, they may switch species, trying to capture species that previously were not high priority, but remain more abundant. In gener‐ al, these species will be smaller, and the trophic cascading associated with the decline in for‐

munities, within the fishery sector, or within the subsistence communities.

which are already stressed and showing evidence of decline.

growth trend, increments in fish production were very slow.

to sell their catch in this large urban market.

and poultry for their traditional fish dishes.

**Figure 4.** Amazonas State and Brazilian Northern region fisheries production between 1992-2010. (Source: 53, 54).

**Figure 5.** Amazonas State GDP per capita and an index of fish production growth [53, 54].

Taking 1992 as the base year both for a fish production index and GDP, it is possible to see that starting in 1995, GDP per capita grew continuously with fluctuations around the trend due to business cycles. At the same time, the index of fish production also grew but with much less intensity. It is clear from the graph that while GDP per capita presented a strong growth trend, increments in fish production were very slow.

What relationships do these trends have with global warming? It is clear that fish produc‐ tion does not drive GDP growth, so global climate change is not likely to have much impact on the GDP of Amazonas through the impact of global change on fisheries. This is not to imply that there would not be critically important impacts through other sectors of the econ‐ omy. Of course, impacts on fisheries would have a large impact on the income of those par‐ ticipating in the commercial fishing industry, and it could have a significant impact on the GDP of small cities in Amazonia (5 to 10 thousand inhabitants) that do not have alternative sources of income. This is particular true for small cities that are sufficiently close to Manaus to sell their catch in this large urban market.

It should be noted that GDP is a measure of market output, not economic benefits and there are a number of ways in which fisheries impact social welfare, both within the ur‐ ban/industrial area and within the rural communities. For example, the output of subsis‐ tence fisheries is explicitly excluded from the measure of GDP because the output is not traded in formal markets. Clearly, small communities will suffer immensely if fisheries are highly impacted by climate change. Moreover, Amazonas has a fish culture, as op‐ posed to the beef culture of the rest of Brazil. As Table I indicates, fish consumption is extraordinarily high, even in urban centers. If fish become scarcer and more expensive, the welfare of the urban centers will be diminished as they are forced to substitute meat and poultry for their traditional fish dishes.

**Figure 4.** Amazonas State and Brazilian Northern region fisheries production between 1992-2010. (Source: 53, 54).

188 New Advances and Contributions to Fish Biology

**Figure 5.** Amazonas State GDP per capita and an index of fish production growth [53, 54].

Taking 1992 as the base year both for a fish production index and GDP, it is possible to see that starting in 1995, GDP per capita grew continuously with fluctuations around the trend due to business cycles. At the same time, the index of fish production also grew but with

The social welfare impacts of global climate change induced impacts on fisheries are diffi‐ cult to calculate. The reason for this is that the direct impacts on fisheries may change eco‐ nomic behavior, which could then lead to a series of indirect impacts that could compound the impacts of climate change. These reactions could occur between urban and rural com‐ munities, within the fishery sector, or within the subsistence communities.

If the impacts of global climate change on fisheries reduce the quality of life of small com‐ munities, it could spur additional migration from the small communities to the urban cen‐ ters. This would increase the urban externalities associated with population increases as a whole, and those associated with immigration of a group of people without training to par‐ ticipate in the service or industrial sectors of the urban center. Moreover, the introduction of more people with a high preference for fish consumption into the urban center will increase the urban demand for fish, putting more pressure on the fisheries near the urban centers, which are already stressed and showing evidence of decline.

People that remain in small communities will continue to be negatively impacted by the de‐ creased fish populations because of the impacts of global climate change. This could lead to several negative impacts. First, they may react to the change by fishing more intensively to try to compensate for the decline in populations. This will further stress the populations that are already stressed by global climate change. Second, they may switch species, trying to capture species that previously were not high priority, but remain more abundant. In gener‐ al, these species will be smaller, and the trophic cascading associated with the decline in for‐ age fish is difficult to predict. Third, they may turn to more hunting to supply their protein needs, leading to other negative impacts on the ecosystem. In particular, the hunting of cai‐ man could lead to impacts on biodiversity as the controlling predators are eliminated from the ecosystem. This would be in addition to the impacts of reductions in intermediate level aquatic predators such as peacock bass (*Cichla* spp.) which would suffer from the negative impacts of global climate change.

tribution to the magnitude of both sources of impacts. We realize that any intervention on the crescendo of climate change needs action of a very large scale or a very large package of small scale actions. Both of these necessitate development strategies arising from a coordi‐ nated source, such as a global agreement. Unhappily, the global negotiations on this issue have made little progress, and we remain distant from an agreement. On the other hand, the effect associated with potential new dams are in the sphere of national decision-making and these impacts could be avoided if the proposed construction does not take place. Thus, it is not too late to find alternatives to Amazonian hydropower for power supply. A global goal to minimize the impacts of both climate change and dams on freshwater fisheries is needed

The Potential Impacts of Global Climatic Changes and Dams on Amazonian Fish and Their Fisheries

Carlos Edwar de Carvalho Freitas1,3\*, Alexandre A. F. Rivas1,3, Caroline Pereira Campos2

, James Randall Kahn1,3, Maria Angélica de Almeida Correa1

[1] Freitas CEC, Siqueira-Souza FK, Prado KLL, Yamamoto KC, Hurd LE. Fish diversity in Amazonian floodplain lakes. International Journal of Medical and Biological Fron‐

[2] Honda EMS, Correa CM, Castelo FP, Zapellini EA. Aspectos gerais do pescado no

[3] Shrimpton R, Giugliano R. Consumo de alimentos e alguns nutriente em Manaus,

[4] Cerdeira RGP, Ruffino ML, Isaac VJ. Consumo de pescado e outros alimentos pela população ribeirinha do Lago Grande de Monte Alegre. Acta Amazonica 1997;27(3):

[5] Batista VS, Inhamuns AJ, Freitas CEC, Freire-Brasil D. Characterization of the fishery in river communities in the low-Solimões/high-Amazon region. Fisheries Manage‐

,

and

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in order to avoid these severe impacts.

\*Address all correspondence to: cefreitas@ufam.edu.br

1 Federal University of Amazonas, Manaus, Amazonas, Brazil

3 Washington and Lee University, Manaus, Amazonas, Brazil

Amazonas. Acta Amazonica 1975;5(1):87-94.

Amazonas. Acta Amazonica 1979;9(1):117-141.

ment and Ecology 1998;5(5):419-435.

2 National Institute for Amazonian Research, Manaus, Amazonas, Brazil

**Author details**

Igor Sant'Ana1

**References**

tiers 2010;16:128-142.

213-227.

Michel Fabiano Catarino2

Worse impacts could potentially occur if the rural populations increased their participation in other extractive activities, including agriculture, timbering and non-timber forest prod‐ ucts. Although the collection of non-timber forest products, such as fruit and fibers is likely to be have a relatively benign direct impact, areas of the forest that were previously not the subject of economic activity could become the subject of economic activity. The heavy pres‐ ence of people in these previously unharvested areas could lead to impacts on fisheries and wildlife, interfering with the ability of these areas to serve as a reserve for repopulating de‐ pleted areas.

Increased participation in timbering and agriculture will lead to deforestation, which has a negative impact on the biodiversity of the forest. Moreover, it will have a negative impact on the aquatic systems. If communities are successful in developing markets for these extrac‐ tive products, it could lead to a reverse migration of people from urban areas back to the forest, leading to an increasing cycle of degradation.

Both the direct effects of global climate change and the indirect effects associated with the reaction to global climate change will have negative impacts on the social welfare of both urban and rural populations. It is likely that a feedback cycle could develop where the reac‐ tion to degradation is more degradation, dramatically reducing both social welfare and eco‐ system function.
