Histograms of the (a) bottom depth distribution of the NASC of Sardinella aurita and S. maderensis from the RV Itaf Deme “ID” (acoustic small pelagic assessment survey covering the Senegambia led in 2004, 2005, and 2007) and pooled NASC of both sardinella from the RV Dr Fridtjof Nansen “DFN” (acoustic small pelagic assessment survey led in 2005 and 2006 with sample (10–19 m) missing); (b) bottom depth distribution of relative catch rates of S. aurita, S. maderensis, Ethmalosa fimbriata and Ilisha africana, from the DFN trawl operation time series (1981–2006; n = 1320).