Fishing techniques used for the exploitation of fish in the flooded swamp forest of the Lake Tumba micro-basin on the Mbandaka-Center for Research in Ecology and Forestry (CREF Mabali) road axis in Bikoro in the Equateur Province (R.D Congo)

The objective of this study was to inventory the different fishing techniques used for the exploitation of fish in the flooded swamp forest of the Lake Tumba micro-basin on the Mbandaka-Center for Research in Ecology and Forestry (CREF Mabali) road axis in Bikoro in the Equateur Province of the Democratic Republic of Congo. The exchange-based surveys were carried out using a pre-established survey form to exchange with the fishermen working in the different study sites in order to obtain the expected data. The harvesting of fish was done in a traditional manner using the different fishing gears and techniques used by the fishermen in the study area. The results obtained show that the majority of the fishing practices implemented in this area are not sustainable. In total, ten (10) fishing techniques were identified, among which five (5) easily provide fish, namely, creel fishing, scooping, fishing with ichthyotoxic plants, longline fishing and line fishing, which are the most used by the fishermen. Four fishing techniques (fishing with traditional traps, scooping, fishing with ichthyotoxic plants and fishing by weeding the areas) were considered non-selective and capable of creating an imbalance in the different aquatic ecosystems surveyed. This study contributes to the improvement of the knowledge on the exploitation of the animal biodiversity of the Democratic Republic of Congo, on the one hand, and on the other hand, the perpetuation of the knowledge of the local population whose obsolete character is not in doubt.

Fishing techniques used for the exploitation of fish in the flooded swamp forest of the Lake Tumba micro-basin on the Mbandaka-Center for Research in Ecology and Forestry (CREF Mabali) road axis in Bikoro in the Equateur Province (R.D Congo)

Introduction
Fishing in Africa is characterized by sustained development in an artisanal manner that contributes strongly to employment (Akonkwa et al., 2017). However, although fishing itself is an important source of employment, previous studies have highlighted that most employment in the fisheries sector is concentrated in post-harvest economic activities, including fish processing and marketing (FAO, , 2017. Fisheries, including aquaculture, make a fundamental contribution to food, employment, recreation, trade, and economic well-being of people around the world, both present and future generations, and should therefore be conducted in a responsible manner (FAO, 2011). Fishery products remain the only source of animal protein readily available among most poor populations (Masua et al., 2020) and, some developing countries (Lusasi et al., 2019a). Fishing is an essential economic sector for many countries around the world and is also an important source of foreign exchange. It provides employment and economic benefit to those who practice it (Danadu et al., 2017;Lusasi et al., 2019b).
The intensity and constancy of fishing pressure in many regions is a matter of concern for the scientific community, as it results in a progressive reduction in the availability of exploited resources , but also in a set of collateral damages affecting in a more or less irreversible way benthic communities and their habitats, as well as populations of the most vulnerable species (Sacchi, 2006).
Fishing is therefore the human activity that exerts the highest pressure on aquatic ecosystems , and this pressure tends to increase with a more intense and efficient fishing effort due to technological improvements, techniques, and fishing gear used (Akonkwa et al., 2017). The intensification of the exploitation of freshwater and brackish fish populations in Africa by local populations is constantly increasing and, above all, the acceleration of the degradation processes of the natural environment poses a major risk of regression and disappearance of species (Lalèyè et al., 2004). The need to take measures for conservation and rational exploitation becomes a major concern .
The species richness of the Congo ichthyo-geographic region is the highest of all African ichthyo-geographic regions described by Roberts (1975), modified by Lévêque (1997); Snoeks et al., (2011) and, is estimated at 1250 species of which 75% are endemic (Snoeks et al., 2011). Globally, it is second only to the Amazon basin (Monsemvula, 2018). In this region, studies have shown that the fishing harvest is significantly higher than its renewal and can produce long-term consequences that can be serious given that the reproduction of fish is conditioned by their sexual maturity (Milandu, 2012;Micha, 2019). The early capture, the intensity of fishing, and the techniques and materials used do not allow the achievement of maximum size or the selection of species in several aquatic ecosystems of the Democratic Republic of Congo .
However, it is important to question the sustainability of fishing in these environments, the persistence of the fish stock, but also the future of the fishermen who work there. It is in this context that this study on the fishing techniques used for the exploitation of fish in the flooded swamp forest of the micro basin of Lake Tumba on the road axis Mbandaka-Center for Research in Ecology and Forestry (CREF Mabali) in Bikoro in the Province of Equateur in the Democratic Republic of the Congo.

Biological material
The different species of fish exploited in an artisanal manner by fishermen in the flooded swamp forest of the Lake Tumba micro-basin on the Mbandaka-CREF Mabali road axis in the Democratic Republic of Congo constitute the biological material of this study.

Methodology 2.3.1. Pre-survey
This stage served to prospect the sites selected for the surveys in order to certify the presence of fishermen in these sites. We used the interview technique to exchange with the fishermen of the sites concerned to get an idea of their availability to respond to our concerns. It also consisted in determining the category of stakeholders who should be the subject of the exchanges.
The inclusion criteria were based on the age of the reason (± 18 years) and the willingness of the person to provide information was also taken into account. Only fishermen from the sites selected for this study were included. Two exlusion critera were taken into account: inhabitants of villages close to the fishing sites and passengers (travelers).

Survey itself
The reasoned choice survey using a convenience sample was used. During the surveys, exchanges were carried out with the fishermen working in the different study sites using a preestablished survey form in order to obtain the expected information. In addition to these exchanges, we also used free interviews for several minutes with fishermen who were motivated to tell us more.
The questions first dealt with the socio-demographic characteristics of the fishermen, notably gender, age, length of time in the fishery, as well as their level of education, in order to evaluate their level of knowledge about the phenomenon under study. Secondly, the questions concerned information on the different gears and techniques used by the fishermen. We also used direct observations to establish the manner in which the fishermen carry out their activity, focusing on the materials and methods used and the size of the fish caught by them.

Sampling and conservation of fish
The harvesting of fish was done in an artisanal manner using the different fishing gears and techniques used by the fishermen of the study area. Experimental fishing was carried out at each site after the surveys on fishing techniques. Data collection took place over eight months covering the period from march to october 2018.
After harvesting, the fish specimens were packed in plastic jars according to the harvesting sites and then, fixed in a 10% formalin solution. For the large samples, vernacular names and photos were taken. The samples thus conditioned were sent to the laboratory for systematic identification.

Systematic identification of fish
The systematic identification of fish was carried out at the Laboratory of Limnology, Hydrobiology and Aquaculture of the Department of Biology of the Faculty of Sciences of the University of Kinshasa. The systematic identification keys of fishes proposed by Lévêque et al. (1990 and1992); Mbega and Teugels (2003);Stianssny et al. (2007) were used for this purpose. We also used vernacular (in Lotomba and Lingala) and common (in French) names of fish collected from fishermen to establish the systematic position of some fish specimens.

Data processing and statistical analysis
The survey data obtained were grouped according to the different categories of questions and then encoded on the Excel 2013 spreadsheet followed by the calculation of their relative abundance expressed as a percentage for each parameter evaluated. The data on the socio-demographic profile of the fishermen as well as on the fishing gears and techniques were compared by means of analyses of variance with a classification criterion (ANOVA 1) (Scherrer, 1984); the Tukey HSD test (Saville, 1990) was used to identify the smallest significant differences between these data at the 95% confidence interval using Statistix version 10 software. The results obtained are presented in tables and graphs. Origin 6.1 software was used to generate the graphs and the mapping of the study sites was done with ArcGIS 10.8 software using geographic data (longitude and latitude) obtained with a GARMIN Etrex GPS. The Ascending Hierarchical Classification (HHC) analysis of the fishing techniques-numerical abundance matrix of fish specimens was performed with Paleontological Statistics software (version 4.0). Table 1 below provides information on the sociodemographic profile of fishermen who harvest fish in the flooded swamp forest of the Lake Tumba micro-basin on the Mbandaka-CREF Mabali road. With regard to the results shown in Table 1 above, it should be noted that the study sample is made up of 196 fishermen working in the stations of Longonye (47 fishermen), Hongo (40 fishermen), Ilunga (24 fishermen), Lotende (30 fishermen) and Membe (55 fishermen). With regard to the gender of the fishermen, 64.80% of those surveyed were men, compared to 35.20% of women. The analysis of variance applied to the number of respondents in relation to gender shows a non-significant difference (F = 4.38; p = 0.0696; Tukey HSD = 12.782) between the number of male and female fishermen. The results of our investigations regarding marital status reveal that a very highly significant difference (F = 18.6; p = 0.0000) exists in the variation in the number of fishermen in relation to their marital status. The critical value of comparison of the Tukey HSD test (7.6675) shows that the married with 103 fishermen, with 52.55%, followed by the single with 57 respondents, with 29.08%, are in the majority, while the widowed with 25 respondents, with 12.76%, and the divorced with 11 persons, with 5.61%. These results corroborate with those obtained by Makuntim (2015); Mboponga (2018); , who revealed the same findings. According to Mboponga (2018), fishing is considered a men's activity in Malebo Pool and, the predominance of married fishermen can be explained in the sense that, married people are called upon to meet the needs of their families so they fish for a living. According to Lusasi et al. (2019b;2020), fishing is a male preserve; women make up more than half of the workforce among the many people who work in the fisheries and aquaculture sector, such as handling, processing and selling fish.

Sociodemographic profile of fishers
With regard to the age group, the results of the analysis of variance show a very significant difference (F = 11.8; p = 0.0002) in the distribution of fishermen by age. The critical comparison value of the Tukey HSD test (7.3791) reveals that the fishermen in the 31-40 age group are the most representative with 92 respondents, with 46.94%, followed by those in the 18-30 age group with 19.39 persons, with 19.39%, and those in the 41-50 age group with 35 respondents, with 17.86%. The fishermen in 51 years old and a rare the least represented, with 19 respondents (9.09%). Ntumba (2012);  also reported that fishing is predominantly practiced by young people between the ages of 25-35 years in the Malebo Pool. These observations are thought to be due to the fact that young people are motivated to seek the means necessary to survive . These results provide ample evidence that fishing is considered an economic activity that provides a livelihood for many Congolese living along the rivers and lakes of the Democratic Republic of Congo.
Concerning the level of education, the comparison of the data by the one-factor variance shows a very significant difference (F = 8.24; p = 0.0015) between the fishermen. With a critical comparison value of 10.615, the Tukey HSD test shows that the majority of fishermen have gone to school. The fishermen with secondary and humanitarian education present 45.41% or 89 respondents followed by those with primary knowledge with 34.18% or 67 fishermen. Fishermen who have not attended school represent 19.39%, with 38 respondents, and fishermen with university level and above are less numerous with 2 respondents, with 1.02%. With regard to the duration of fishing, it should be noted that most of the fishermen have been practicing this activity for several years. The results of the one-way analysis of variance show that there is a highly significant difference (F = 7.82; p = 0.0001) between the fishermen with regard to the duration of fishing. The critical value of the Tukey HSD test (6.0382) reveals that the fishermen who have totaled between 11 and 15 years are more numerous with 49 respondents, with 25%, followed by those who have totaled between 16 and 20 years with 48 fishermen, with 24.49%, then those who have totaled between 6 and 10 years of fishing represent 19.39%, with 38 respondents, and the fishermen who have fished between 1 and 5 years represent 16.84%. The fishermen least represented in terms of the duration of this activity are those who have been fishing for 30 years or more. These observations are sufficient proof that the fishermen who exploit the fish in the streams, ponds, and swamps of the flooded swamp forest of the Lake Tumba microbasin on the Mbandaka-CREF Mabali road have acquired considerable experience in fishing activities.

3.2.
Analysis of fishing activity in the flooded swamp forest 3.2.1. Fishing equipment used The different materials used by fishermen to collect fish in the streams, ponds and swamps of the flooded swamp forest of the Lake Tumba micro-basin on the Mbandaka-CREF Mabali road are shown in Table 2. In total, seven (7) types of fishing equipment are identified among fishermen who exploit fish in the flooded swamp forest of the Lake Tumba micro-basin on the Mbandaka-CREF Mabali road axis. In general, the one-factor analysis of variance applied to these data shows a highly significant difference (F = 7.98; p = 0.0000) between the frequency of use of fishing equipment; the Tukey HSD test reveals that traditional traps with 27.64% of citations, nets made of insecticideimpregnated mosquito netting with 21.14%, ichthyotoxic plants with 17.07% and hooks with 14.63% are the fishing materials most used by these fishermen (Fig. 2); still nets, sparrow nets and harpoons are used to a small extent. In terms of fishing sites, traditional traps with 31 quotes or 29.81% followed by hooks with 24 quotes or 23.03%, nets made of mosquito netting impregnated with insecticide with 16 quotes or 15.38% and ichthyotoxic plants with 14 quotes or 13.46% are frequently used in the Longonye site. In the Hongo site, traditional traps with 26 quotes or 23.85%, fish-eating plants and nets impregnated with insecticide with 21 quotes or 19.27% respectively and hooks are the most used in fishing. In the Ilungu site, the materials most used are traditional traps (32.56%), followed by nets impregnated with insecticide (25.58%), hooks (18.60%) and ichthyotoxic plants (11.63%). In Lotende, traditional traps with 17 quotes (28.33%) followed by hooks with 13 quotes (21.67%), fish nets and nets made of insecticide-impregnated mosquito netting with 9 quotes (15%) are the materials frequently used by fishermen. In the Membe site, traditional traps (27.64%), landing nets impregnated with insecticide (21.14%), ichthyotoxic plants (17.07%) and hooks (14.63%) are the materials most frequently used by the fishermen. These observations are similar to those made by Akonkwa et al. (2017); Matita (2020); . In their studies, the latter noted the use of dip nets, nets of all kinds, hooks, traditional traps, harpoons, chemical products and ichthyotoxic plants by fishermen who exploit fish in the Congo River in the Malebo Pool and Lake Kivu in the Democratic Republic of Congo.

Different fishing techniques used
The different fishing techniques used by fishermen exploiting the rivers, ponds and swamps of the flooded swamp forest of the Lake Tumba micro-basin on the Mbandaka-CREF Mabali road axis are recorded in Table 3. The information in Table 3 above shows that ten fishing techniques are used by fishermen who exploit the fish in the rivers, ponds and swamps of the flooded swamp forest of the Lake Tumba micro-basin on the Mbandaka-CREF Mabali road axis. Of all these techniques, creel fishing with 84 quotations (19.72%), scooping with 66 quotations (15.49%), fishing with ichthyotoxic plants with 60 quotations (14.08%) and longline fishing with 51 quotations (11.97%) are the fishing techniques most frequently used by the fishermen. Fishing with harpoon, gillnets and weeding of the areas with 21 quotations or 4.93% are used to a small extent. Poor fishing practices constitute a problem for the renewal of organisms (Luhusu and Micha, 2013) because overexploitation associated with destructive gears and techniques leaves no chance for aquatic animal species to reproduce and develop well . In several studies conducted in Lake Mai-Ndombe in the Democratic Republic of Congo, Luhusu and Micha (2013); Micha (2019) note that mosquito nets with a mesh size of 2 mm no longer allow for the natural recruitment of species classically captured as adults with gillnets in this aquatic ecosystem.

Fishing techniques that provide easy access to fish
The results visualized in Figure 3 below inform us that five (5) fishing techniques provide fish easily. Of all these techniques, creel fishing (24.4%), scooping (22%), and fishing with ichthyotoxic plants (19.9%) are the most solicited by the fishermen who exploit the fish in the rivers, ponds, and swamps of the flooded swampy forest of the Lake Tumba micro-basin on the Mbandaka-CREF Mabali road axis. They are followed by longline fishing (17.7%) and line fishing (16.4%). The frequency of use of the traditional creel in the study area is due to the fact that this gear is easy to obtain; it is designed by the fishermen themselves by pulling the creel's spawning inputs from the forest, but also to the fishing tradition in this area, which has used the creel for years to collect fish. The pyrethroid insecticides (such as deltamethrin and permethrin) used for impregnating nets (Equiterre, 2019) are safe for humans but very harmful to aquatic invertebrates. The use of landing nets made with insecticide-impregnated mosquito netting is related to the types of habitats (ponds and swamps) that are generally shallow where these fishermen harvest fish. Boika et al. (2022) showed in their research that the depth of the water column is shallow across the different ponds, swamps, and rivers in the flooded swamp forest; it varies from 84.5±38.5 cm (Membe) to 113.75±46.25 cm (Longonye); these shallow depths are a major asset in the use of landing nets.

Reasons for the choice of fishing techniques used
The reasons given by the fishermen to justify the choice of fishing techniques used to exploit the fish in the study area are listed in Table 4. The fishermen justify the choice of fishing techniques implemented in the study area by five (5) reasons. Among these reasons, profitability in relation to the quantity of fish caught (24.26%), the cost of acquiring equipment (23.99%), the possibility of catching all sizes of fish (23.45%) and the low demand for fishing effort (18.33%) are the reasons given by the respondents to justify the choice of a fishing technique. The use of ichthyotoxic plants in the study area is justified according to the fishermen by the ease of collecting and obtaining fish in large quantities with less fishing effort, but also most often by women. According to Kimpouni et al. (2011), women most often use empirical techniques ranging from scooping to the use of ichthyotoxic plants. The use of ichthyotoxic plant extracts is a sampling technique well known to scientists (Lévêque and Paugy, 2006). This illegal fishing with ichthyotoxic plants, which is practiced in the lakes and rivers of the Congo Basin, has indeed become widespread over the past several years (Kimpouni et al. 2011). These plants are ineffective in large bodies of water or in running water; generally they are used in marshes with an area of no more than forty ares (Kimpouni et al. 2011). The use of ichthyotoxics is mostly effective, quantitatively, in closed-type environments such as ponds,... etc; in open water, or in fast currents, the use of ichthyotoxics gives much more random results due to the escape of the poison (Leveque and Paugy, 2006). Without direct harmful influence on humans, the plant substances used in this type of fishing are toxic to fish, amphibians, and freshwater invertebrates and, inhibit the filtration capacity of bivalve mollusks (Micha, 2019).

Time spent fishing
The results shown in figure 4 below indicate that the majority of respondents (36.6%) fish for 12 hours, followed by those who fish for 6 hours (29.6%), 24 hours (19%), and less than 6 hours (14.8%).
14.8% 29.6% 36.6% 19% 24 hours 12 hours 6 hours or less Less than 6 hours Fish species exploited in the surveyed sites The different species of fish caught with the different fishing techniques used by the fishermen who exploit the rivers, ponds, and swamps of the flooded swamp forest of the Lake Tumba micro-basin on the Mbandaka-CREF Mabali road axis are recorded in Table 5. The results in Table 5 above show that twenty-six (26) species of fish grouped in ten (10) orders, fifteen (15) families and twenty (20) genera are identified in the flooded swamp forest of the Lake Tumba micro-basin on the Mbandaka-CREF Mabali road. These results are close to those obtained by Mathes (1964); Boika et al., (2021); Boika et al., (2022). In contrast, Boika et al., (2022) noted the presence of twenty-two (22) species of fish divided into 15 genera, 13 families and 10 orders. Mathes (1964) reports the presence of thirty-one (31) species inventoried during his study in the same area of Lake Tumba. According to Boika et al., (2022), the difference in catches could be explained by the fishing techniques used, the area exploited and the duration and period of sampling.

Relative abundance of the orders of fish identified
Of the ten orders of fish identified, fish of the orders Siluriformes with four families or 26.7%, Osteoglossiformes and Perciformes with two families or 13.3% respectively are the most numerous (Fig. 5). The remains of the orders are less represented with one family or 6.67% respectively.   figure 6 below that in terms of genera, the family Clariidae is the most representative with three genera or 15.8% followed by the families Cichlidae and Mormyridae with two genera each or 10.5%. The rest of the families are represented by only one genus or 5.26%.

Relative abundance of fish genera surveyed
The information shown in figure 7 below reveals that the fish grouped in the genus Ctenopoma (19%), Clarias (8%) and Hemichromis (8%) are more numerous than those of the other genera, which represent 4% for each of the genera Figure 7. Relative abundance (%) of the genera of the fishes surveyed 3.3.4. Selectivity of fishing techniques and numerical abundance of fish in the catches The selectivity of the different fishing techniques used and the numerical abundance of fish in the catches with the same techniques are shown in Table 6. A total of 1,636 fish specimens were recorded during this study. Of all the fishing techniques used during the sampling, traditional creel fishing with 388 fish specimens captured, i.e. 23.70% of occurrence, scooping with 308 fish specimens captured, with 18.81% of occurrence, ichthyotoxic plant fishing with 306 fish specimens captured, with 18.69% of occurrence, and site weeding fishing with 230 fish specimens, with 14.05% of occurrence, are the ones that facilitate the capture of the fish in the study area. The remaining fishing techniques were found to be selective by their low percentage of occurrence. The dendrogram of similarity established between the fishing techniques and the numerical abundance of fish species according to these techniques shows two large groups that are significantly different (correlation coefficient = 0.8654) (Fig. 8). The first group is composed of four fishing techniques (traditional trap fishing, scooping, fishing with ichthyotoxic plants and fishing by weeding the areas) considered non-selective. The second group is made up of the remains of the fishing techniques .  68  64  60  56  52  48  44  40  36  32  28  24  20  16  12  8  4 Euclidean distance

Conclusion
The overall objective of this study was to identify the different fishing techniques used in the exploitation of fish in the flooded swamp forest of the Lake Tumba micro-basin on the Mbandaka-Center for Research in Ecology and Forestry (CREF Mabali) road axis in Bikoro in the Equateur Province of the Democratic Republic of Congo. The results obtained showed that the majority of the fishing practices implemented in this area are not sustainable. In total, ten (10) fishing techniques were identified, among which five (5) easily provide fish, namely creel fishing, scooping, fishing with ichthyotoxic plants, longline fishing and line fishing, which are the most used by the fishermen. Four fishing techniques (fishing with traditional traps, scooping, fishing with ichthyotoxic plants and fishing by weeding the areas) were considered non-selective and capable of creating an imbalance in the different aquatic ecosystems surveyed. Changes in fishing practices are strongly desired to avoid increasing food insecurity by reducing, through overexploitation, the access of populations to this precious and excellent halieutic resource.