Terrestrial waters provide multiple goods and services to human kind, but they have been severely diminished by increasing human exploitation of water and the landscapes surrounding aquatic communities. This research illuminates such dynamics in the recent history of exploitation of the Lake Bam fishery in Burkina Faso. To do so, from 2009 to 2015 we collected data on the ecology, exploitation and governance of the Lake Bam fishery. Direct sampling of fish documented the erosion of fish diversity and the reduction of fish size and the number of landings. Interviews with leaders of riverside community suggest a halting and uncertain transition in the governance of natural aquatic resources from the traditional (pre-colonial) approach to a republican (European democratic) one. The number of fishermen exceeds the fishery’s carrying capacity, but the number of fishermen continues to rise, driven by the low level of opportunities in alternative livelihoods. National and international awareness regarding the lake’s ecological and socio-economic importance has driven restoration projects that can benefit from these findings.
Aquatic ecosystems provide many services that contribute to human well-being and poverty alleviation. In developing countries, inland ï¬sheries are extremely important since they are sources of animal protein, employment and income for rural populations (Millennium Ecosystem Assessment, 2005). Worldwide the settlement of large cities along river courses over the past millennia indicates that human life has long been strongly linked to aquatic ecosystem services (Baron et al., 2002). While the deficient management of freshwaters has led to their overexploitation and disturbance (Malmqvist and Rundle, 2002; Humphries and Winemiller, 2009), there is an increasing awareness to promote their conservation. The conservation of freshwaters requires their monitoring and assessment of the extent to which they are impacted. To Karr (1981) fish are commonly used to assess the overall health of aquatic ecosystems and their fisheries. Thus, determining the current status of fish communities gives information on the status of the body of water the communities occupy.
This bio-metric approach was adapted and applied in many areas in the world: Guinea (Hugueny et al., 1996), South Africa (Kleynhans, 1999; Rashleigh et al., 2009), Argentina (Crettaz‑Minaglia and Juarez, 2020), Brazil (Gonino et al., 2020), Nigeria (Ali et al., 2017), Europe (Schmutz et al., 2007; Blabolil et al., 2017; Ergönül et al., 2018; Specziár and ErÅ‘s, 2020), Côte d’Ivoire (Aboua et al., 2012), India (Basavaraja et al., 2014). It relies on the principle that fish respond to stress on aquatic ecosystems, and that these responses (Table 1) are sustained for a relatively long period of time, e.g. a time period long enough to suggest impacts and potential responses relevant to management policy. A range of relevant research (Table 1) has documented how indicators, such as the level of catch, the species mean adult length, the number of species, the type of species, the number of diseased and deformed fishes are used to assess the quality of a freshwater and the fishery that it offers. However, the lack of reliable data and information on fish and fisheries is a reality in Burkina Faso (Ouédraogo, 2010). For example, the main reliable document available on the lake Bam fishery that is Coenen (1988) is so old that it is likely not so relevant to policy. In and of itself it is not scientific research, but more of a collation of information summarized in a report as part of preparation for a fishery development project undertaken by the FAO. The other available documents are some reports that were prepared in 2005 as part of a lake rehabilitation project. To address this lack of data based on rigorous sampling and analysis, the present work aims to describe the historical changes in Lake Bam fishery in terms of fish community assemblage, commercial total landings and aquatic habitat quality. For the first time it documents the fish species in the lake and the fishing community.
The study area
Lake Bam is located in the northern part of the country next to Kongoussi, the capital city of the Province of Bam (Figure 1). This largest natural water body in Burkina Faso is included in the catchment of the Nakanbé River, the second most important tributary of the Volta River. Because the lake is fed exclusively by runoff during the rainy season, its size varies from 600 ha during the dry season to 2600 ha during the rainy one. Currently the lake volume is said to be depleted as a result of mismanagement of its resources (Ouédraogo, 2010), and a project for its rehabilitation was officially launched in March 2017 (APPEAR, 2018) and is currently being implemented.
Data collection
Three methods were used to gather all available information about the Lake Bam. A survey of literature was conducted for historical data to itemise the above-mentioned indicators concerning Lake Bam. Then, selected stakeholders and experts were interviewed. Using a variety of fishing gears (cast nets, electric fishing, gillnets and long lines), fish were sampled to provide an overview on the fish community. The sampling of fish and the interviews were implemented from June to August 2009. This initial round of research was followed by the collection of complementary data from the fishermen and local community leaders.
The interviews
Interviews provided a survey of data based on the experience and knowledge of local fishermen. To do so, a workshop was held with 25 fishermen whose age ranged from 25 to 60 years. As aged people often are better informed by their long experience than youths (Leopold et al., 2008), we interviewed a retired fisherman, approximately 85 years-old, with some 60 years fishing experience on Lake Bam. The objective was to collect historical data on the use of fishing gear, the fishing community, fish landings and species composition. When sampling for fish in Lake Bam, these questions were also raised in discussion with local, currently active fishermen who were part of the sampling team.
The management of the lake continues to shift from traditional to republican regimes. The original, historical regime was established and run by the traditional communities that are led by the Naba and the Tengsoba. Its authority is based on customary beliefs and animist religion. The second regime was introduced by the colonizing power from Europe and is supposed to be supported by the evidence derived from scientific analysis of natural resources and the communities that exploit those resources. To gather information about lake management under the traditional regime, we interviewed two villagers who represent the traditional authority of their villages:
(i) Naba Tigré: living in the village of Zimtanga, he is the Chief of the Canton of Datinga, an administrative area that is supposed to regroup more than 100 villages and that includes about 90 % of the lake water area and the surrounding upland catchment.
(ii) Tengsoba Yaalé: the Tengsoba is the person traditionally responsible for natural resources management in the Mossi ethnic group, including the area of Bam. According to the local fishermen we interviewed, Tengsoba Yaalé represents the traditional authority in the management of Lake Bam. He is living in Bam Village, which is located about 10 km away from Zimtanga.
The sampling of fish
In early July 2009, we sampled fish with long lines, gillnets, cast nets and electric fishing. The specimens were classified into species according to Lévêque et al. (1990, 1992); their total length (TL) and body weight (W) were measured. Fish were sampled in the lake itself, as well as in the main and secondary tributaries a few hours after it had rained. The rain aided our sampling since fish often become concentrated at the brook mouths and migrates upstream as soon it rains (Bénech and Quensière, 1987).
Data analysis
To highlight the historical changes in the fishery, we organized the data into the following categories: climatic and hydro-morphologic features, the governance of the lake and its resources, fishing pressure and the fishery production, changes in the fish community, restoration actions. We then analysed the dynamic trends of these entities over time.
Climatic and hydro-morphologic features
The lake relies exclusively on rain to be filled, but the annual rainfall shows a general decreasing trend over the past century. From 878 mm in 1927 it dropped to 572.6 mm in 2008. Figure 2 illustrates a clear 35% decrease of the rainfall trend from 1927 to 2015 despite the missing of data from 1980 to 1989.
Rainfall in the Sahel region is usually scarce and patchily distributed. According to Ouédraogo (2010), the sparse, upland vegetation and the patchy, intense patterns of precipitation contribute to strong soil erosion, and these results in the transportation of significant quantities of sediments to the lake. With about 500,000 m3 of sediments deposited every year, the lake lost one third of its water volume, as measured by depth, between 1963 and 2006. If this trend continues, lake water storage capacity will vanish, and the lake will disappear in a quarter of century. The elderly villagers who participated in this survey said that, the lake is increasing in area as it becomes shallower and shallower. They illustrated this by showing areas that formerly surrounded the lake where they were farming maize, sorghum and millet some 3-5 decades ago. But the pieces of land on which they used to farm are now flooded by August, the middle of the rainy period that lasts from June to September. Furthermore, the lake loses large quantities of water due to (i) the heat that resulted in high evaporation (ii) abstraction of large quantities of water for irrigation. The surface water temperature ranges from 18 to 42°C, and the evaporation rate is about 7 mm/day (Pouyaud, 1986). As a result, the lake water surface declines by 1.5 m over the course of the year, a significant decrease for a lake that is 2-3 m deep during the rainy season.
Water management within Lake Bam catchment
In arid regions like the Sahel, people have historically dug small size ponds to store water to be used during the dry season. Today, larger reservoirs are created and many others are under construction as the demand for water increases year-by-year. According to a national list of water bodies developed a decade ago, the lake catchment currently hosts 45 reservoirs; all sizes included (Figure 3).
The dams are not supplied with migratory devices, e.g. fish ladders, the absence of which, in all probability impedes the migration of fish. Furthermore, upstream reservoirs have to be filled before the water flows into the lake, which delays the filling of the lake as compared to what it was in the past.
Pollution and degradation of habitat
According to the fishermen, fish mortality is gradually increasing as water levels increasingly decline during the fish community’s most vulnerable period, from April to June, the variable and unpredictable end of the dry season before the rainy season starts. Firstly, this may be due to increasing pollution concentrations in the water column as pollution rates in runoff increase at the same time that the lake’s volume decreases. Observations on the river banks during the dry season, confirmed by Google maps, show the presence of large, irrigated, vegetable farms in the immediate surroundings of Lake Bam. The same irrigated lands used to grow vegetables during the dry season are rain-fed farms of sorghum and of other cereals during the rainy season from July to October. Local experts of agriculture explain that the farmers use large quantities of fertilisers and pesticides. Inadequate government oversight or control results in overuse of these chemicals, and the excess is washed into the streams and the lake during the rainy season. Secondly, the area surrounding Bam is grazed by a significant population of livestock, estimated at more than 100 000 animals, all types included (Ouédraogo, 2010). Animal nutrient deposition across the landscape is washed by runoff to Lake Bam, thereby increasing the nutrient input (Derlet et al., 2010). The fishermen observed that, in entering the lake to drink water, the cattle stir up bottom sediments, making the water more turbid, and defecate, increasing the organic loading of the water column, the decomposition of which increases oxygen demand. The resultant hypoxia during the period of lowest water levels may increase stress and mortalities in fish.
Changes in the fishery governance
The traditional management approaches
Elderly and traditional authority leaders explained that before colonisation in the early 20th century, riverside people managed the lake according to their own rules, values, and understandings. That traditional belief system is consecrated by more than 12 holy sites existing in and around the lake along the shore area. From time to time, sacrifices were offered to prevent harm to the community, such as drowning, floods and diseases, and to ensure fruitful usages of the resources (such as fish and water), and for the wealth of people in general. The offerings can include one or many of the following items: traditional beer, sesame, bean cakes, black bullock, black goat, black hen, donkey, dog and horse. The dog and the horse replace human being which was formerly used as a sacrifice. Additional items may be required depending on the circumstances of the sacrifice. Sacrifices for the benefit of the entire community were ordered by a group of wise people, and the Chief of the Canton had to provide the ingredients. To do so, he used to send people to walk around and to catch any animal that roams freely. On 23rd May 2013, we witnessed a sacrifice event that the fishermen of Lake Bam asked Yaalé to proceed for fishing to be productive (Figure 4).
In former times, the rules were legitimized and enforced by a group of wise people led by the Tengsoba and acknowledged and followed by the community in general. By this approach the Lake and the other natural resources were managed. For instance, when declining water levels broke the lake into separate pools, some pools were designated to be open to domestic animals, some for domestic needs, but all were managed for fish conservation. During this period fishing and hunting for crocodiles were strictly forbidden, a ban that generally protected aquatic biodiversity. Clearing large areas of land cover of vegetation was subject to the approval of the Tengsoba. Medicinal trees, trees producing edible fruits and holy forests were always strictly protected. Hunting and cutting trees were seasonally restricted. During the protection period, no wildlife animal could be killed, because they were thought to be pregnant. But killing wildlife such as snakes for human protection was allowed and even encouraged.
Anyone who witnesses a violation event was expected to report to the authority. A range of punishments were applied for different offences, but a person who repeatedly violates the rules was gradually marginalised. For instance, this person was not properly greeted by anybody in the community. The ultimate sentence was the drowning of the guilty person in the lake. Not only was finding the dead body extremely difficult, but the person was then qualified as donkey; and as animal and could not benefit from a proper funeral. This extreme condemnation was greatly detested in the community.
The republican management approaches
In the early to mid-20th century, the French colonial administration introduced new rules governing natural resources. The elderly respondents in our interviews reported some republican management policies that they could not understand, nor accept:
(i) Overnight, local people lost the ownership of the lake, which was now allocated to the State. But the new owner was not present to implement their rules.
(ii) For leisure purposes the French colonisers cleaned the lake banks from vegetation. Then they used to cross the lake with a motorised boat, to swim and to fish.
(iii) No foreign fisherman was allowed to catch fish in the lake, and rules for foreigners willing to undertake any activity other than fishing existed. But the coloniser invited professional fishermen from the neighboring Republic of Mali to fish in the lake without seeking the agreement of the indigenous people.
(iv) Six to seven decades ago the colonial administration introduced a fishing tax or licence of 6000 FCFA/year/ fisherman, the equivalent of 9.15 Euro or the price of two 4-year old bulls or two new bicycles. This was much higher than what the average, indigenous citizen could afford. For comparison, at that time, the colonial administration introduced a national Head tax for all citizens. The entire city of Kongoussi, the biggest agglomeration next to the lake had to pay only 15 FCFA/year (that is, 0.02 €). But this amount was seldom met by the city, meaning that the fishing tax was unreasonably high.
Today the Naba Tigre, Chief of the Canton of Datinga, and the Tengsoba are both calling for a reorientation of the lake management to better accommodate and integrate traditional authorities within what is, ostensibly, a republican regime. To explain previous failures to accomplish this, the Naba, points out that the republican system tries to involve the traditional authority but from a wrong perspective. He is frequently invited for meetings regarding the lake, which regrettably he has no strong authority to manage, because he manages people but not natural resources. In addition to his invitation, he has suggested that the Tengsoba also be solicited, because he is the most appropriate for managing natural resources following the traditional approach. According to the Tengsoba, the government or any other governing body has to provide them with the ingredients for sacrifice for the community’s benefit. This is necessary because the Naba can no longer order the free catching of animals for sacrifices. People still respect and believe in the Tengsoba power as they often come to him for assistance.
The exploitation of fish resources
Historically, riverside people were fishing for subsistence using elementary gear. Commercial fishing was introduced in Bam in 1953 by the French colonial administrator, who invited some professional fishermen from the River Niger in the Republic of Mali to fish the lake. With a much longer fishing tradition than what existed at that time in Burkina Faso, they brought more efficient gear, such as cast nets, gill nets, long lines and canoes. Their number reached 30 some years later, but they left the lake more than a quarter of a century ago. In addition to their role as trainers for local people with little previous history of fishing, these fishers were providing fish products to local markets and to Ouagadougou the main city of the country that is 110 km far in the South. Half a century ago about 100 persons were fishing in the lake. Today there are about 650-700 fishermen inhabiting the 36 riverside villages.
The fishermen mentioned a remarkable decrease of catches over the past 70 years. From about 50 kg of fish per day in 1950 the landings of a fisherman dropped to 2.3 kg in 1987 and to 0.5 kg in 2009. The total landing of the lake was estimated at 175 t in 1990, 150 t in 2000 and about 80 t in 2009 (Ouédraogo, 2010).
Historical changes in the fish community
The fishermen described the historical changes in the fish community as they witnessed or heard from elder people. Six decades ago, the fish community was dominated at about 60% by two species: Clarias gariepinus and Heterotis niloticus. They were followed by Polypterus sp., Synodontis sp., Auchenoglanis occidentalis, Protopterus annectens and the tilapia group which together contribute at 35 % to the fish community. Alestes species and Brycinus specie were rare, as together they contributed to about 5% to the fish community. Barbus sp. appeared during that period.
Three decades ago, C. gariepinus and H. niloticus were still dominant, Polypterus specie, Synodontis specie, P. annectens and the tilapias frequent, Alestes specie and Brycinus specie were relatively frequent as compared to Barbus specie which was rare. The mormyrid family, Hydrocynus specie, Heterobranchus specie and Malapterurus electricus appeared at that time. Heterobranchus specie was somehow frequent, and very large specimens were often caught. Lates niloticus was twice introduced but never established. The only written document about the Lake Bam fish community Coenen (1988) mentioned 21 species in the commercial landings but estimated that the lake was hosting 30 species regrouped in 11 families. Sarotherodon galilaeus was dominant (39.1%), followed by Oreochromis niloticus (16.3%), Brycinus nurse (9.9%), Marcusenius senegalensis (9.1%), Schilbe intermedius (8.9%), Auchenoglanis occidentalis (5.6%) and Synodontis schall (4.2%); the other species contributed 6.9%.
In 2009, some fifty-two sampling events yielded 2533 fish, regrouped in 20 species and 9 families. Two species strongly dominated: Sarotherodon galilaeus (30.2 %) and Enteromius ablabes (26.3%). They were followed by Chelaethiops bibie (6.5%) and Enteromius macrops (5.9%). Oreochromis niloticus, Clarias gariepinus, Coptodon zillii and Hemichromis letourneauxi contributed at 4% each. Together the 11 remaining species contributed a total of 15%. The fishermen pointed out that nowadays Heterotis niloticus and Heterobranchus sp. still exist, but they are extremely rare and seasonal (Table 1).
In 2009 the maximum total length (TL in mm) was 119 for S. galilaeus, 85 for E. ablabes, 310 for C. gariepinus and 160 for O. niloticus. Table 2 shows the species list, the relative frequencies and the size of fish in Lake Bam. A comparison of data in Coenen (1988) and ours shows that a likely loss of 8 species and a decrease in fish mean weight over 20 years (Table 3).
Social impacts of the lake and its resources
Today, there are 650-700 fishermen inhabiting the 36 riverside villages. But only 3-5 of them rely more or less exclusively on fishing for their daily livelihood. It means that most fishermen are also involved in other economic activities, such as rain-fed agriculture, irrigated agriculture, livestock breeding, selling of goods, artisanal mining of gold, etc, and only take up fishing as an additional income source. Such occasional fishermen often lack the experience or knowledge to fish sustainably. In contrast to former times, forbidden fishing methods are currently commonly used. They include nets of small mesh size, unsuitable long lines, beach seine, poisoning, etc.
In addition, about 600 women are involved in the post-harvest segment of the fishery. They sell fresh fish, smoke fish that they later sell, fry and cook fish in small restaurants. Seasonality is observed in the fishery. During the rainy season, the fishers are all involved in rain-fed agriculture that is labor-intensive. Therefore, they allocate the least time to fishing by tending to use passive gear, such as gillnets and long lines. The fishermen also indicated that by this time, as there is much water in the lake, fishing is rather less productive. During the dry season, as water levels decline and concentrate the fish the fishing becomes more intensive. The fishermen tend to fish more when money-demanding social events are planned: festivals (e.g. Christmas), funerals, when children return to school in October after the long holidays, etc. The fishermen affirmed that without fishing, they would have to sell their crops or domestic animals to meet the cash needs of these occasions.
Previously, the fish production of Lake Bam was collected by fishmongers coming from Ouagadougou and sold in that city. Today, it is exclusively sold in local markets and even has to meet the competition from fish imported from Asia, Côte d’Ivoire and other countries and sold in the areas surrounding the lake. This means that the lake fishery is less and less competitive, and perhaps is so depleted that it has to be completely rehabilitated through significantly higher levels of investment and effort.
The restoration actions undertaken in Lake Bam
To support rehabilitation of Lake Bam, significant attention is given to lake conservation. In 2009 the lake was allocated the status of a Ramsar site - a recognition of its international ecological importance (Government du Burkina Faso, 2009). To protect the lake, trees are being planted on the banks and stony walls (bunds) built on the brooks to slow down the transportation of sediment into the lake (Figure 5). The first stony walls were built by a Germany-funded project dedicated to restore the soils of the areas to improve agriculture. Today, many NGOs and associations now pursue projects that prioritize the lake’s protection. Some brooks whose 2.5 m deep accelerated runoff rates and erosion are now filled of sand and used for agriculture.
The lake is currently being rehabilitated under a project that was launched 03 March 2017 (APPEAR, 2018). The restoration project has two phases. The first step consists mainly, in erecting a 25 cm high wall at the downstream edge of the lake, in intensifying the irrigated farming of vegetables, protecting the lake resources, studying the possibility of dredging and enhancing the fishery. As for fish, the project planned to farm fish for restocking, and to provide the fishing community with equipment for fishing and processing fish. But noticeably no fish related research activity is planned (MAH, 2012). The second step will consist in dredging the lake, if feasible, to increase the lake’s depth and water storage capacity.
