More than 12 million people work in fisheries in Africa, including more than 2.3 million women. Fish represents, on average, 22% of the protein intake in sub-Saharan Africa; in some countries, this level exceeds 50%. For example, the food security of the Senegalese population depends largely on fish resources: nearly 70% of the animal protein consumed is derived from the sea. Senegal is the second largest fish-producing country in West Africa and now exceeds 500,000 tonnes extracted per year. Estuarine and lagoon fish assemblages are of great importance for fisheries in West Africa, both being directly exploited by local fishermen and constituting nursery areas for many marine species targeted by coastal fisheries.

Knowledge and monitoring of biodiversity is therefore an important issue in West Africa, both in terms of knowledge of aquatic environments and the assessment of aquatic resources for sustainable use. The ecosystem approach to fisheries advocated by FAO particularly requires this type of information. The dataset presented here is of special importance in this context because it combines both old data (the taxonomy of which have been reviewed in the light of current knowledge) and recent data, thus allowing an approach to the temporal evolution of biodiversity. This database is the largest experimental fisheries catch database for West Africa and covers both a large temporal range (more than three decades) and a large spatial range in West Africa (12 ecosystems in seven countries). It comprises fish occurrences mainly from estuarine and lagoon ecosystems (Ebrié lagoon, Sine Saloum estuary including Bamboung MPA, Fatala estuary, Rio Grande de Buba, Gambia estuary), but also from coastal ecosystems (Bijagos archipelago including Urok Island MPA, Banc d'Arguin National Park and Dangara inlet) and also two reservoir lakes (Manantali and Selingue).

After having developed the PPEAO information system, we then felt it was important to provide it with greater visibility and accessibility for the international scientific community. GBIF.org is probably the major global portal for the provision of this type of data, which justifies the choice made here to use it.

Starting in the early 1960s, the French «Office de la Recherche Scientifique et Technique Outre-Mer» (ORSTOM), which in 1998 became the «Institut de Recherche pour le Développement» (IRD), studied West African aquatic ecosystems. These studies included sampling of aquatic communities by scientists and surveys of artisanal fisheries that exploit the ecosystems. Several research programmes focused on various estuarine, lagoon, coastal and lake ecosystems in West Africa involving the same scientific team succeeded one another between 1979 and 2013. From 2001 onwards, the IRD research programme “Adaptative responses of fish populations and assemblages to the environmental pressures” (“Réponses Adaptatives des populations et des peuplements de Poissons aux pressions de l’environnement”, French acronym RAP) funded the development of two MS-Access databases and of the software needed for their management and for user consultation: “Pechart” for the artisanal fisheries database (Ndiaye et al. 2003a) and “Pechexp” for the experimental fishing database (Ndiaye et al. 2003b). In these two databases, historical data (1980-2000) was gathered in a homogeneous format along with new data collected in the RAP research programme between 2001 and 2008. Then, in 2006, to make the data available to a wider scientific community, the two databases were merged into one PostgreSQL database, which is located on an IRD server. The development of this database, called PPEAO for “Peuplements de poissons et Pêche artisanale des Ecosystèmes estuariens, lagunaires et continentaux d'Afrique de l'Ouest” and of its management and consultation software, were funded by IRD, through the support project “Soutien aux Projets Informatiques dans les équipes Scientifiques” (SPIRALES – Ecoutin et al. 2007). PPEAO software can be accessed at http://ppeao.ird.fr.

A first dataset gathering all the species occurrences observed by experimental fishing was extracted from PPEAO and put online on GBIF.org. It is available at 10.15468/ra4voa. The present datapaper describes this dataset, which corresponds to 213 fishing surveys, 5,362 fishing hauls and 31,709 occurrences (28,428 of fish taxa and 3,281 of crustaceans and molluscs). The number of individuals per species and per haul is available and 80% of occurrences are geolocated. In the following section, we provide a general description of the dataset, after which we give a more detailed description of each ecosystem with their respective sampling protocols.

We now provide a detailed description of the climate, geography, sampling protocol and main characteristics of the assemblages in each monitored ecosystem in chronological order. In the case of the Sine Saloum delta, which was the target for several research projects from the 1990s to the 2000s, all the sampling periods are included in the same section. Conversely, the Bamboung MPA, situated in the Sine Saloum delta, was the subject of a particular monitoring programme and is described separately. Sampling in 1993 in Guinea-Bissau and monitoring of the Urok Islands MPA between 2011 and 2013 are also described separately because they had different objectives.

Sample collectors: Jean-Jacques Albaret, Jean-Marc Ecoutin and Jean Raffray.

The largest coastal lagoon in West Africa extends around Abidjan, over approximately 130 km along the coast of Côte d’Ivoire (Fig. 3). It is located between 5.2° and 5.45° North and 3.7° and 4.8° West. It never exceeds 7 km in width for an average depth of 4.8 m and a surface area of 566 km² (Durand et al. 1994). This lagoon is subject to a double influence: freshwater influence from rainfall and river flow, especially from the Comoé River situated at the East end of the lagoon and marine influence via the Vridi canal which provides permanent access to the sea. There are three distinct seasons: a dry season from January to April, a rainy season from May to August and a flood season from September to December (Durand and Chantraine 1982).

In the 1970s, a comprehensive research programme on the environment and the aquatic resources of the Ebrié lagoon was conducted (Durand et al. 1994). This included a study of the fish assemblages of the lagoon conducted by scientists from Orstom and “Centre de Recherches Océanographiques” of Abidjan, from December 1979 to August 1982. The aim of the study was to describe the distribution and functioning of fish assemblages in relation to changes in environmental conditions in space and over time. The results are summarised in a book on environment and aquatic resources of Côte d’Ivoire (Durand et al. 1994) by Albaret (1994) and in a more recent article by Ecoutin et al. (2005). Several other publications, based on these data, describe the ecology and the biology of the main lagoon fish species.

Based on preliminary studies, the Ebrié lagoon was divided into six sectors. The Vridi canal separates two dissymetric parts: sectors I and II are located in the east part and sectors IV to VI in the west part. In the centre, sector III is directly influenced by the Atlantic Ocean via the Vridi canal. In the sampling protocol of the fish assemblages, around 80 sampling sites were defined covering all six sectors.

Two kinds of sampling gear were used: trawls and purse seines. The trawls had the following characteristics: vertical opening 1.5 m – headrope 10 m – mesh size 20 mm. The 137 trawl hauls were only conducted in sector III, the most maritime area of the Ebrié lagoon, from December 1979 to August 1982. The purse seine (300 m long, 18 m deep with a 14 mm mesh size) was used to sample the whole Ebrié lagoon in a total of 406 hauls. The most extreme sectors (I, V and VI) were only sampled in two seasons: in the middle of the dry season (February and March 1981) and at the end of the rainy season – beginning of the flood season (October 1980 and August-September 1981). The central sectors (II, II and IV) were sampled at approximately two-monthly intervals, alternating between the west and the east part of the lagoon, between February 1980 and October 1981. Finally, the bay of Cocody, located in the town of Abidjan, was sampled monthly with a purse seine from October 1980 to October 1981 and the results were published by Albaret and Ecoutin (1990).

Sampling of Ebrié lagoon recorded 6,537 fish occurrences, corresponding to 60 families and 113 taxa, all identified at the species level (Table 5). The Clupeidae family clearly dominated the fish assemblages, with Ethmalosa fimbriata accounting for more than 70% of the occurrences, followed by Sardinella maderensis (7%). Other families were also well represented: Carangidae with Chloroscombrus chrysurus (2.8%), Claroteidae with Chrysichthys maurus and Chrysichthys nigrodigitatus (2.4 and 1.6%, respectively), Paralichthyidae with Citharichthys stampflii (2.1%) and Gerreidae with Gerres nigri and Eucinostomus melanopterus (2.1 and 0.9%, respectively).

During these sampling campaigns, 16 taxa other than fish were recorded, corresponding to 1,007 occurrences: 69% of the individuals were identified at the species level, 24% at the genus level, 0.5% at the family level and 6% at the class level. They were mainly penaeid shrimps Penaeus notialis, jellyfish (Scyphozoa) and crabs belonging to the genus Callinectes.

Sample Collectors: Jean-Jacques Albaret, Papa Samba Diouf, Jean Raffray, Oumar Sadio, Luis Tito de Morais and Guy Vidy.

The Sine Saloum delta is located 100 km south of Dakar and north of the Gambia River and Casamance estuaries between 13.6° and 14.2° North and 15.8° and 16.8° West (Fig. 4). It has three main branches from north to south: the Saloum, the Diomboss and the Bandiala. These branches are shallow (10 to 15 m deep in the centre of the channel, with a maximum depth of 25 m in some places). The branches are interconnected by a dense network of seawater creeks locally named “bolongs”, resulting in two groups of islands, partially covered with mangrove. Eight ecological zones have been defined in the Sine Saloum delta (Diouf 1996): Z1 to Z3 in the Bandiala, Z4 in the Diomboss, considered as homogeneous and Z5 to Z8 in the Saloum. The estuary drains a watershed of 29,720 km². The Sudanese type climate is characterised by two seasons: a short, wet and warm season from July to October and an extended dry season, cool from November to March and warm from April to June. Due to the very low gradient of the watershed and the lack of rain, the Sine Saloum is an inverse estuary, i.e. salinity increases upstream, particularly in the Saloum branch. The fish assemblages in this delta have been studied in several research programmes since the early 1990s.

The 1990s

In the early 1990s, a research programme was conducted in the Sine Saloum delta by Orstom and the “Centre de Recherche Océanographique de Dakar Thiaroye” (CRODT), part of the “Institut Sénégalais de Recherches Agricoles” (ISRA), with the collaboration of the “Ecosystèmes Lagunaires” laboratory belonging to Montpellier University, France. This research programme was funded by Orstom. The dataset contains data collected between 1990 and 1997 by the two components of the programme. The “adult and subadult fish assemblages” component was conducted by Jean-Jacques Albaret and the results were published by Diouf (1996) and later by Simier et al. (2004). For the “juvenile fish assemblages” component, conducted by Guy Vidy (Vidy 2000), the dataset specifically comprises data collected using fyke nets.

Two types of fishing gear were used to sample adult and subadult fish assemblages: beach seines and purse seines. Samplings using a “long” beach seine (180 m long, 9 m deep with a 25 mm mesh) were conducted in April, June and September 1990. In December 1990, a few trials were conducted using a “truncated” beach seine and a 100 m long purse seine. From April 1991 to May 1993, a standardised sampling protocol was used with a purse seine 250 m long, 18 m deep with a 14 mm mesh size. Ten sampling sites were defined covering the eight zones of the Sine Saloum delta. On each sampling occasion, each site was sampled twice, one haul in the middle of the channel and the other near the bank, to obtain a representative picture of the diverse habitats. All the sites were sampled at two or three monthly intervals, except the two sites in zone Z8, upstream of the Saloum, which were sampled only twice: once during the wet season (October 1992) and once during the dry season (February 1993). A few “off-protocol” surveys were also done, using the same purse seine, but without following the standardised protocol. Surveys carried out in July, August and September 1994 only covered small “bolongs” fish assemblages. Finally, a last survey was carried out in January 1997 following the standardised protocol.

The study of juvenile fish assemblages began at the end of 1994 and ended at the beginning of 1997 (Vidy 2000). Only the mangrove area was sampled. After a period of adjustment of the sampling technique and gear, the survey lasted two years. The main sampling gear was a fyke net 2.5 m long and 0.4 m in diameter, inspired by the “capéchades” used in the South of France. The net was completed by two wings each 1.5 m long and by a 4 m long “wall” to guide the fish towards the trap. The mesh size was 6 mm for the wall and 3 mm for the second half of the trap. Sampling took place every month at night during the new moon phase, at flood tide to catch the fish entering the mangrove corridors. Two successive strategies were used. In 1995, three sites were sampled on two consecutive nights, with four traps, giving an eight samples set per site and per month. This period was dedicated to the characterisation of seasonal variability of the juvenile fish community. In 1996, three more sites were added and the six sites were sampled on only one night using six traps. The aim of this strategy was to obtain details on the spatial organisation of juvenile fish.

Early 2000s

In the early 2000s, the Sine Saloum delta was chosen by the RAP research unit for a comparative study with the nearby Gambia River estuary. The research programme was funded by IRD. The aim of this comparative study of the fish assemblages between the inverse Sine Saloum estuary and the normal Gambia River estuary was to better understand the impact of a major climatic disturbance, hypersalinity. For this reason, more samplings were conducted in the hypersaline upstream area of the Saloum than in the 1990s.

Concerning the sampling of adult and subadult fish assemblages in the main channels, a preliminary survey was conducted in March 2002, followed by three surveys using the same standardised protocol: in May 2002 (dry and warm season), October 2002 (wet and warm season) and March 2003 (dry and cool season). During each survey, 30 purse seine hauls were done at 18 sampling sites (13 in the Saloum, one in the Diomboss and four in the Bandiala). As in the 1990s, most of the sites were sampled twice on a given date: one haul in the mid-channel and the other one close to the bank. In the Saloum, six sites were sampled only once per survey, as well as the two Bolong Dioto sites in the Bandiala. The sampling gear was a purse seine 250 m long, 18 m deep with a 14 mm mesh size. The results were published by Ecoutin et al. (2010). Two additional surveys, not using the standardised protocol, were carried out in 2004.

The main fishing gear used for the sampling of juvenile fish assemblages was a fyke net, which was also used in the Gambia River estuary during the same period (Vidy et al. 2004). The gear comprised two parts: the first was a “wall” 8 m long, 3 m high with an 8 mm mesh size. The “wall” was used to guide the fish towards the second part of the trap, the fyke net itself, 3 m long and 0.4 m in diameter, with two wings each 2.5 m long. The mesh size of the fyke net was 6 mm. For each survey, eight traps were deployed at each site for one night, in or near the mangrove, at a maximum depth of 3 m. Fish sampling was carried out in the new moon phase, at flood tide, in order to catch the fish entering the mangrove corridors.

Years 2005-2006

In 2005 and 2006, scientists of the RAP research unit chose to focus on the biological indicators of the state of health of fish populations and assemblages. The aim was to develop a set of indicators that could be analysed jointly to assess the extent of a disturbance in aquatic ecosystems. This work was conducted in the context of the GIBAO project (Groupement Indicateurs Biologiques d’Afrique de l’Ouest). It was funded by IRD, with financial help from the Sub-Regional Fisheries Commission (CSRP) of West Africa, as part of the Regional Partnership for Coastal and Marine conservation (PRCM).

Targeted operations were conducted in the form of purse seine fish samplings. Six sampling sites were defined, one in the uspstream area of the Bandiala (zone 3), the five others in the Saloum (zones 6, 7 and 8), not including the mouth area. During each survey, between 3 and 9 stations were sampled per site. Samplings were made using a purse seine 250 m long, 18 m deep with a 14 mm mesh size. All the hauls were classified as “off protocol” because they did not cover the entire Sine Saloum delta.

General description of catch data

The consecutive research programmes in the Sine Saloum delta recorded 8,567 fish occurrences, in all the periods combined, corresponding to 56 families and 126 taxa, 95.5% of them being identified at the species level, 2.5% at the genus level and 2% at the family level (Table 6). The Clupeidae family dominated the assemblages, 35% of the occurrences were Sardinella maderensis and 22% Ethmalosa fimbriata. Cichlidae were well represented with three species: Sarotherodon melanotheron (10% of occurrences), Hemichromis fasciatus and Coptodon guineensis (less abundant with 0.4 and 0.3% occurrences, respectively). Pristigasteridae Ilisha africana accounted for 8.7% of occurrences, while Haemulidae Brachydeuterus auritus and Carangidae Chloroscombrus chrysurus accounted for 3.2 and 2.3% of occurrences, respectively. Gerreidae, with Gerres nigri (5%) and Eucinostomus melanopterus (3.3%) and Mugilidae (Chelon dumerili, Neochelon falcipinnis, Parachelon grandisquamis, Mugil cephalus and Mugil curema) also represented a significant component (3.6%) of the fish assemblages in the Sine Saloum delta.

During the samplings in the Sine Saloum delta, 969 occurrences representing 14 taxa other than fish were also recorded, of which 66.7% were identified at the species level, 18.3% at the genus level, 7.9% at the family level and 7% at the order level. Most of the occurrences corresponded to shrimps Penaeus notialis and crabs Callinectes amnicola. Some cephalopoda (Loliginidae and Sepia) were also quite often collected.

Sample Collectors: Jean-Jacques Albaret, Eric Baran.

In order to assess the influence of the riverine system on the estuarine ichthyfauna, a comparative study was conducted in Guinea between January 1993 and March 1994. The aim of the study was to compare the fish assemblages in the estuary of the Fatala River with those in the neighbouring Dangara inlet, located 20 km away and not connected to a river. This study was conducted by Eric Baran for his PhD thesis (Baran 1995), which was directed by Christian Lévêque and advised by Jean-Jacques Albaret. The whole research programme was funded by Orstom, in cooperation with the inland fisheries department of the “Centre National des Sciences Halieutiques de Boussoura” (CNSHB). The study area was located in the coastal zone of Boffa, which belongs to the “Southern Rivers” region (Fig. 5). It is located between 10° and 10.3° North and 14° and 14.25° West. The tropical wet climate is characterised by a dry season from November to May and a wet season from June to October with peak rainfall in July. Rainfall is very high (approximately 3,500 mm/year) with the hydrological cycle reaching a maximum in August or September (Baran 1995).

In the Fatala estuary, the estuarine zone is limited by a rock sill 60 km upstream which stops both the dynamic and saline actions of the tide. As the area 10 km upstream of the estuarine zone could not be accessed by boat, sampling was limited to the downstream 50 kilometres. Two fishing gears, a purse seine and gillnets, were used alternately every month, to obtain a comprehensive description of fish assemblage variability. The purse seine (250 m long, 18 m deep with a 14 mm mesh size) was used every two months from January 1993 to January 1994, at eight equidistant sites, one of which was located in the ocean in front of the river mouth. Each site was sampled during daylight, each time with two hauls, one haul in the mid-channel and the other as near as possible to the bank (minimum water level: 2 m). The gillnets were set up in parallel and close to the bank, in order to provide a better sampling of riparian fish assemblages. A gillnet set was composed of ten panels of different mesh size (10, 12.5, 15, 17.5, 20, 22.5, 25, 30, 35 and 40 mm). Each panel was 25 m long and 2 m deep. Four sampling sites, the same as those used for the purse seine samplings, were located 3, 17, 33 and 46 km from the mouth, respectively. At each site, four “stations” were defined, corresponding to two subsequent nights on both sides of the estuary. In the Dangara inlet, three sites were defined. Dangara surveys took place immediately before or after those in the Fatala estuary, i.e. every two months. Only purse seine samplings were performed, twice at each site as in the Fatala estuary (mid-channel and close to the bank).

Together, the samplings performed during this study in Guinea recorded 3,910 fish occurrences, corresponding to 40 families and 86 taxa, 99.8% of which being identified at the species level and 0.2% at the genus level (Table 7). The Pristigasteridae Ilisha africana dominated the fish assemblages with 35.3% of the occurrences, followed by the Sciaenidae Pseudotolithus elongatus (14%) and the Carangidae Chloroscombrus chrysurus (8.5%). Clupeidae Sardinella maderensis, Ethmalosa fimbriata and Pellonula leonensis represented 8.7%, 7.1% and 4.4% of the occurrences, respectively. Haemulidae Brachydeuterus auritus accounted for 4.2% of the occurrences. Mugilidae were rare in the Fatala estuary and the Dangara inlet, except for Neochelon falcipinnis and Parachelon grandisquamis (2% each). The same applies to the Gerreidae family, which was only represented by Eucinostomus melanopterus (0.7%).

Only fish were collected during this study and no information is available about taxa other than fish.

Sample Collectors: Jean-Jacques Albaret, Papa Samba Diouf and Itaf Deme-Gningue.

The Bijagos Archipelago is located off the coast of Guinea-Bissau between 10.9° and 11.6° North and 15.6° and 16.5° West. The Rio Grande de Buba is a small coastal river flowing in the west central region of Guinea-Bissau, between 11.4° and 11.7° North and 15° and 15.5° West. It flows into the Atlantic Ocean in front of the Bijagos Archipelago (Fig. 6).

Following a request from the “Centre Canadien d’Etudes et de Coopération Internationale” (CECI), a team from Orstom and the “Centre de Recherche Océanographique de Dakar Thiaroye” (CRODT - Sénégal) carried out a scientific survey in the Bijagos Archipelago at the end of March 1993. This team was composed of Itaf Deme-Gningue and Pape Samba Diouf from CRODT and Jean-Jacques Albaret from Orstom. Scientists and technicians from the Fisheries Department of Guinea-Bissau and from CECI also took part in the survey. Following this survey, a second survey was carried out by the same team in the Rio Grande de Buba at the begining of April 1993 in response to a request from the International Union for Conservation of Nature (IUCN). Jean-Louis Kromer (UICN) participated in this survey. The results of the surveys were published in two scientific reports (Deme-Gningue et al. 1994 and Diouf et al. 1994).

In the Bijagos Archipelago and the Rio Grande de Buba, a sampling plan of 36 and 24 sites, respectively, was followed, considering the diversity of habitats and bathymetry. The GPS positions were recorded for the Bijagos Archipelago, but not for the Rio Grande de Buba. The main fishing gear used was a purse seine (250 m long, 18 m deep with a 14 mm mesh size). At some sites, a beach seine was used to provide information about riparian fish communities. It was used either instead of the purse seine (at sites 25 and 30 in the Bijagos Archipelago) or in addition to it (at sites 32 and 34 in the Bijagos Archipelago and sites 1 and 10 in the Rio Grande de Buba). This beach seine was 50 m long, 2 m depth with a 30 mm size for the wings and 14 mm mesh for the bunt.

The two surveys performed in 1993 in the Bijagos Archipelago and the Rio Grande de Buba in Guinea-Bissau recorded 258 fish occurrences, corresponding to 43 families and 60 taxa; all fish were identified at the species level (Table 8). The Carangidae Chloroscombrus chrysurus dominated the assemblages with 51.5% of occurrences. The Gerreidae Eucinostomus melanopterus and Gerres nigri accounted for 17.6 and 5.4% of occurrences, respectively. The two Clupeidae Sardinella maderensis and Ethmalosa fimbriata accounted for 7.7% and 1.4% and the Pristigasteridae Ilisha africana 2.1%, respectively.

During these two surveys, 28 occurrences of taxa other than fish were identified. They belonged to five taxa, mainly shrimp Penaeus notialis and crabs belonging to the genus Callinectes.

Sample Collectors: Jean-Jacques Albaret, Famara Darboe, Jean, Luis Tito de Morais and Guy Vidy.

At the begining of the 2000s, the Gambia River estuary was chosen by the RAP research unit of IRD as a reference ecosystem for a comparison of West African estuarine fish assemblages. The Gambia River estuary has rarely been disturbed by drought and functions like a “normal” estuary, with no upstream dams; it is surrounded by an abundant mangrove in good condition, with little pollution and subject to low fishing pressure.

A joint IRD/Gambian Fisheries Department research programme was conducted from 2001 to 2003, for the “Evaluation of the fish resources and estuarine resources stewardship of the Gambia River”. It was funded by the French Department for Cultural Action and Co-operation (SCAC). The study area comprised the lower, middle and upper estuary, from Banjul at the mouth to Deer Island 220 km upstream (Fig. 7). The Gambia estuary is located between 13.2° and 13.7° North and 15° and 16.6° West. In this region, the wet season extends from June to October, with peak rainfall in August. The cool dry season lasts from November to March and the warm dry season from April to June.

Five surveys were conducted to characterise the adult and subadult fish assemblages in the main stream of the Gambia River estuary, covering the whole hydrological cycle. Not all the subsequently sampled sites were visited during the preliminary survey (November 2000), whereas six of the originally envisaged sites were abandoned after the preliminary survey. During each of the four following surveys (June 2001, September 2001, December 2001 and April 2002), 44 sites were sampled, only using a purse seine (250 m long, 18 m deep with a 14 mm mesh size). The results were published by Albaret et al. (2004) and Simier et al. (2006).

Eight surveys were conducted between September 2001 and November 2003 to study mangrove juvenile fish assemblages. The first two surveys in 2001 enabled the sampling protocol to be adjusted. Then, in 2002 and 2003, three surveys per year were conducted between May and November, the season of maximum juvenile recruitment, at six sites along the estuary. The main gear used to sample juvenile fish was the same as that used in the Sine Saloum delta during the same period (see above). The results were published by Vidy et al. (2004).

Together, the samplings performed in the Gambia River estuary recorded 3,710 fish occurrences, corresponding to 40 families and 92 taxa, almost all identified at the species level (Table 9). The Sciaenidae Pseudotolihus elongatus was predominant, accounting for 35.8% of the occurrences, followed by the Clupeidae Ethmalosa fimbriata (22.1%) and the Pristigasteridae Ilisha africana (11.7%). Another Clupeidae, Sardinella maderensis, accounted for 6.4% of the occurrences and the Mugilidae Parachelon grandisquamis for 3.5%. Unlike the other ecosystems studied, three freshwater fish were identified amongst the 20 main fish taxa in the Gambia River estuary: the two Mochokidae Synodontis gambiensis (3.4%) and Synodontis batensoda (1.1%) and the Schilbeidae Schilbe intermedius (0.6%).

During the survey of the Gambia River estuary, 893 occurrences of taxa other than fish were recorded. They corresponded to 10 taxa, mostly Callinectes amnicola and Penaeus notialis.