Changes in climatic and environmental conditions today constitute threat to local populations in Burkina Faso [1] and to the survival of biodiversity [2] with a certain ecological impact [3]. According to the IPCC [4], these climate changes are likely to compromise ecosystems’ sustainability and their services. Worldwide, fishery resources contribute more than 10% of the animal’s protein ration for about 4 billion people [5]. In Africa, fish is the main source of animal protein for rural populations [6]. In Burkina Faso, it contributes to about 8% of the protein coverage of food needs and 3% of gross domestic product (GDP) [7]. In addition, we note that the landlocked position of Burkina Faso and the sources of its economy which are essentially based on agriculture make it even more vulnerable to climate change. Thus, activities such as fishing whose productivity is strongly influenced by climatic variables like rainfall and temperature are threatened by these global changes. An additional factor is the non-compliance with fishing regulations [8]. A reduction in fishery production risks jeopardizing the achievement of the Sustainable Development Goals (SDGs) by impacting its Goal2 which is to “…End hunger, achieve food security and improve nutrition, and promote sustainable agriculture”. However, climatic hazards, in addition to population growth, may weigh more heavily on ecosystem services. Indeed, the modification of fish habitats due to climatic and environmental hazards such as irregular rainfall, rising temperature, anthropogenic activities, extreme weather conditions will have a negative impact on the size of fish and their geographic distribution [3] [9]. Several studies have already addressed the perception of environmental and climate change by local communities [10] [11] [12], but very few were interested in the way it is perceived by fishing communities. However, for a sustainable management of fisheries, it is important to better understand how fishermen perceive the effect of different pressures on fish and their habitat. In Burkina Faso, according to statistics from the Ministry in charge of Fisheries Resources, fish production has increased since the 2000s despite the decrease in fish catch per fisherman. This implicitly indicates an increase in the number of fishermen. According to some authors, this decline could be explained by the effect of anthropogenic pressures [13]. By the past, many studies have shown that local people possess endogenous knowledge and strategies to manage sustainably their natural resources [14]. For other authors, local actors often ignore the ecological problems generated by climate change [15]. In addition, insufficient knowledge of the fisheries creates uncertainties related to the quantity and quality of the catches [5] and constitutes a factor limiting the sustainable management of the fishery [16]. This work answers the following research question: “What understanding do local fishermen have of anthropogenic and climatic pressures influence on fish fauna in Burkina Faso?” To answer this question, we hypothesized that fishermen, as the first direct actors of fishing, could have interesting information on the nature and intensity of environmental and climatic pressures affecting fish fauna, on the one hand, and could develop best strategies to adapt themselves to environmental change, on the other hand. This work’s general objective is to assess the perception of environmental and climatic changes by direct actors, namely local fishermen in the Volta basin fishery in Burkina Faso. To achieve this, specific objectives have been defined: 1) identify the different pressures likely to have an impact on fish diversity; 2), assess the occurrence of perception of these pressures by fishermen, 3) identify the groups or species of fish threatened by these anthropogenic and climatic pressures and 4) determine the local strategies adaptation.

Fish resources in Burkina Faso are impacted by climate change and anthropic pressures and fishermen are aware of this situation. Some studies have already mentioned same perception by local farmers in Burkina Faso [18] [19]. This study is a contribution to monitoring the effects of global change at the local level and the related adaptation strategies by fishermen in Burkina Faso particularly in Volta basin. The perception indicators were correlated with the professional experience of the fishermen surveyed. Then, although the number of threats perceived does not seem to be correlated to the age group, it can be noted that the type of threat is a function of the age group of the fishermen. This was confirmed by the Kruskall Wallis test, which showed that there was a statistically significant difference in the perception of the different pressures, whereas the difference in terms of the number of pressures perceived by each of the three age groups was not significant. Similar work had also been done by Nago et al. [20], Kaboré et al. [21] and Hounkponou et al. [22]. In the researches of Nago et al. the groups of respondents were analyzed according to the types of perception determinants cited. Concerning the research of Kaboré et al. it was mentioned the Farmers’ perceptions of climate change, environmental impacts and endogenous adaptive strategies in the North Central of Burkina Faso. While, the work of Hounkponou et al. was about correlating the factors determining perception and the ages of the respondents on the one hand and the coping strategies in relation

to the level of prosperity on the other. The data collected during this study were mainly pressures causing the death and/or the disappearance of fish in the long term and fish which are concerned by the, factors causing water column fluctuation. The decrease in the water column of the reservoir could be explained by the consequences of climate change such as the decrease in rainfall [9] as well as the silting due to vegetable farming in the reservoir or around it. We could also note the effect of wind and water erosion; this is even more plausible for certain sites like Zangoula in Bagré reservoir where the northern part of the reservoir is devoid of any plant cover. Agricultural and electrical activities had already been reported by fishermen in Mali as being responsible for the decrease in floodings in the Inner Niger Delta [9]. Regarding the rise of reservoirs water temperature, in addition to the impact of climate change, Kyle et al. have shown that other variables such as solar radiation, the rising air temperature and plant cover could also increase the temperature of aquatic environment [23]. Arimoro et al. showed a strong positive correlation between the temperature of water and the temperature of ambient air [24].

On the decrease of the water level

The decrease in the water column of the reservoir could also be explained by the impacts of climate change such as the decrease in precipitation [9], evaporation due to the increase of temperature [25] as well as silting due to market gardening in or around the reservoirs. The effect of wind and water erosion could also be noted. Agricultural and electrical activities have been reported by fishermen in Mali to be responsible for reduced flooding in the Inner Niger Delta [9]. In Ghana, Laube et al. found a decrease of about 10% in mean annual rainfall across the Volta Basin, of which our study area is a part [26].

In terms of increasing water temperature in reservoirs, in addition to climate change impacts, it is showed that other variables such as solar radiation, increased air temperature, and lack of vegetation cover could also increase the temperature of the aquatic environment. Arimoro et al. have also showed a strong positive correlation between water temperature and ambient air temperature [24]. In a recent study, 72% and 87% of the surveyed households respectively informed about the increase in seasonal temperatures as well as the decrease in rainfall in their study sites (in Eastern Ghana and Southwestern Burkina Faso) [27].

On fish mortality

Seasonal mortality of fish concerns mainly the Mormyridae, Cichlidae and Mochokidae families’. Of all the species subject to seasonal mortality, species of the Mormyridae family are the most affected. As for the variables that would cause this mortality, the main ones would be marsh pollution, water temperature increase, first rains and bad fishing practices. Previous studies have shown a positive correlation between rising temperatures and mortality in human populations in Nouna [28]. It could be the same effect with aquatic communities and particularly, with fish fauna. According to the fishermen’s groups interviewed, Mormyridae are a group of fish with high fat content and therefore vulnerable to large increases in water temperature. In addition, studies have also highlighted their status as intolerable species [29]. Other studies have shown that changes in water temperature and dissolved oxygen are problematic for aquatic organisms such as fish [30]. Therefore, these changes in temperature and dissolved oxygen can lead to fish death [31]. There is little data on the pH range of Mormyropsanguilloides. However, since its thermal preferences are very low and vary between 22˚C min and 24˚C max (www.fishbase.org), this could explain its inability to adapt to large temperature variations such as high heat during hot periods. In addition, it is a species that prefers deep and calm waters. Arimoro et al. [24] also showed that Mormyridae, like species of many other families such as Schilbeidae, Clariidae, Bagridae, among others, are very sensitive species to organic pollution. Indeed, the first rains are likely to drain household waste such as very basic ashes that could degrade the quality of the receiving ecosystem. Pesticides used in market gardening and agriculture would also contribute to deteriorate the quality of aquatic ecosystems with, as a corollary, the death of fish [32]. Some authors have also shown that the agricultural method could have negative effects on fisheries production [33]. Indeed, agricultural residues such as nitrogen derivatives (ammonium) can, at certain concentrations, lead to fish death [34].

On the disappearance of fish

Pressures causing fish extinction frequently cited by fishermen include the opening of the dike resulting in fish migration to Ghana. Indeed, the construction of dams without fishways constitutes a barrier that prevents the migration of fish from downstream to upstream reservoirs. Others pressures are also cited by fishermen. These were poor fishing practices and pesticide pollution. In fact, the effects of pollution from agriculture on fish could be indirect by causing increased siltation and reduced dissolved oxygen availability [35]. In 2016, Lam et al. concluded after a study in coastal West African countries that the rate of current fishing pressure would result in declining fish stocks [36]. Among the endangered fish species highlighted in this study, some species such as Heterotisniloticus and Latesniloticus had already been reported by fishermen in the Sahelian Lake Higa in 2012 as having disappeared from their fishing grounds [16]. Codjo, et al. in a study conducted in Lake Toho in southern Benin had also shown an extinction of large fish in general and species of the genus Hydrocynus, Heterotis, Clarias and Gymnarchus in particular [37]. Other studies have also highlighted the adverse effect of human activities on fish fauna [38] [39].

Other fish stressors and limitations of pressures cited

Among the fish stressors, a group of fishermen from Beguédo (in the upstream part of Bagré reservoir) mentioned the beating of the water not as a stressor but rather as a factor responsible for the concealment or burying of fish. According to these fishermen, the beating of the water cannot stress the fish but only causes a temporary modification of their habitat. This shows a lack of knowledge about the effects of certain fishing practices. Other fishermen also cited the opening of the dam gates during the flood period as a stressful variable, although this seems normal. In addition, the lack of a fishway downstream of the dam could explain the lack of fish return upstream. This again shows that some fishermen are unaware of fish stressors. However, for the vast majority of fishermen, beyond their knowledge of the harmful environmental and anthropogenic pressures on ichthyofauna, we note that they are also aware of the manifestations of climate change. A study by Nielsen and Reenberg [40] showed the perception of the same climatic variables by local populations located in the Burkinabe Sahel.

The pressures perceived by fishermen are found in the literature. Indeed, in several previous works carried out in Burkina Faso [25] [41] [42], pressures such as pesticide pollution, dam construction, overfishing, extreme weather events, temperature rise, evaporation and climate change have been cited as influencing water bodies as well as aquatic resources. A sociological study by Ayeri et al. in Kenya also showed that local stakeholders perceive the effects of climate change [43]. These include decreasing rainfall, increasing temperature, increasing frequency and intensity of high winds, the occurrence of famine in human populations and diseases in animals.

In addition, the work of Coulibaly et al. showed that the ability of fish to harbor certain parasites constitutes a threat to both the fisheries resource and a public health problem [44]. Yao et al. in Ivory Coast [45] and Rindoria [46] also demonstrated that fishery resources were negatively impacted by household waste and microbiological pollution. At none of the sites surveyed was parasitism reported as a pressure on fish resources. Several other studies conducted at the local level have shown that fish are hosts to parasites [47] - [52]. Thus, fishermen appear to be unaware of the effect of parasitism on the health status of fish.

Adaptation measures and management strategies

From the interviews conducted, adaptation is mainly through training, awareness and compliance. This shows the low resilience of fishermen to the adverse effects of climate change. In addition, other studies carried out in other countries have proposed adaptation and management measures. These include combating soil erosion through reforestation, increasing the carrying capacity of reservoirs [53], promoting and introducing adapted fish species [54] or using regulated nets and engaging in other income-generating activities [37]. On the national level, adaptation measures in the face of the adverse effects of changes such as the construction of water reservoirs has also been undertaken since the second half of the 20th century [1]. In addition, exchanges with resource persons have shown that fishermen migrate according to the availability of fish resources to other localities. This is further verified by the fact that some studies such as Henry et al. explained that migratory flows would be justified by a population adaptation strategy to climate change [55].

The fishery resources of Burkina Faso are affected negatively by environmental variables change. This study allowed us to assess the endogenous knowledge of fishermen in the Volta Basin with regard to the environmental and climatic impact on the lakes ichthyofauna. We were also able to establish the frequency of the various pressures and inventory the most endangered fish species. The data collected confirms our research hypothesis, namely, that fishermen perceive the nature and intensity of the pressures exerted on the ichthyological fauna in the basin level. Fishermen noted a decrease in the quantity and quality of fish catches due to the various stresses. These consequences will be all the more important in the future if no mitigation and/or adaptation measures are taken. However, some fishermen ignore the impact of certain pressures on the fish fauna. Therefore, it is important that measures are taken by decision-makers to promote the sustainable management of fishery. These include 1) taking fishways into account when building dams, 2) strengthening the technical skills of fishermen, 3) supporting and equipping fishery managers and 4) raising the awareness of the less well-equipped actors about the harmful effects of bad fishing practices. Finally, this study contributes to identify the different pressures on fisheries that are perceived by the fishermen of Burkina Faso and particularly those of our study sites.

The authors are grateful to the Sustainable Management of Water and Fish Resources in Burkina Faso (SUSFISH-plus) project which funded a part of the fieldwork. Funded itself by the Austrian Partnership Programme in Higher Education and Research for Development (APPEAR), this project aims to establish sustainable fisheries and water management through the improvement of higher education and governance in Burkina Faso. The authors are also grateful to fishermen who accepted to be interviewed and shared their knowledge about fisheries treats with them.

The authors have not declared any conflict of interests.

Silga, R.P., Oueda, A., Kpoda, W.N., Mano, K., Ouedraogo, I., Weesie, D.M.P. and Kabre, B.G. (2021) Fishermen Local Knowledge and Aquatic Environmental Change: Impacts on Fishing and Adaptation Strategies in Volta Basin. Open Journal of Ecology, 11, 507-526. https://doi.org/10.4236/oje.2021.117033