Sampling

Sampling took place in the years 2012–2013, from the Cunene River mouth in northern Namibia, to Port Elizabeth in South Africa, covering the entire distribution range of both species (Fig. 1). Samples were obtained from Namibian and South African governmental research surveys and commercial fisheries by trawling. A piece of muscle was collected immediately after capture and stored in 95% ethanol. DNA was extracted using a standard chlorophorm:isopropanol method (Winnepenninckx, Backeljau & Dewachter, 1993).

Sampling strategy for M. capensis and M. paradoxus across Southern Africa: N, Namibia (N = 413); W, West Coast (N = 302); SW, Southwest Coast (N = 288); S, South Coast (N = 160).