A comparative study of fossil fish scales from three upwelling regions

In anoxic conditions, fish scales accumulate in the sediment undisturbed by benthic burrowing organisms and unaffected by aerobic bacterial decomposition. Other workers have studied the accumulation of scales in sediment off California and Peru to give insight into past fish populations. Suitable anaerobic conditions for a similar study exist off Walvis Bay, Namibia. The fish scales in 30 cm of laminated, undisturbed diatomaceous mud cored off Walvis Bay were analysed and the results compared with those from California and Peru. Pre-fishery clupeoid populations in each of the three regions apparently experienced fluctuations of the same order of magnitude as those recorded more recently by the fishing industries. The Namibian system differs from the Pacific system in that, in the central areas at least, it is historically dominated by pilchard Sardinops ocellatus.