(a) Map of the study area (Senegambia) and plot of the fishing operations from three vessels: RV Dr Fridtjof Nansen (DFN), RV Itaf Deme (ID) and Diassanga. The zoom shows the localisation of Bamboung and Sangako in Saloum delta (adapted from Sadio and Ecoutin (2013) where the Diassanga led its inshore fishing operations. Acoustic sampling design in parallel transects (DFN and ID) is overlaid in grey line. The isobath lines are shown in red (500 m), blue (100 m), green (500 m) and purple (30 m). (b) Map of the geographi graphical distribution of Ethmalosa fimbriata, Sardinella aurita, Sardinella maderensis, and Ilisha africana sampled from scientific trawl survey (1981–2006). The total surveyed area [10–500 m] is 5600 NM² vs. 1700 NM² [0–10 m] not surveyed (shallow part along the coast, in blue).