Excerpts from "Foraging and Farming in Egypt" by Wilma Wetterstrom from The Archaeology of Africa edited by Thurston Shaw, Paul Sinclair, Bassey Andah and Alex Okpoko (Link)
"Beginning about 21,000 BP, many of the sites [in the Nile valley] began producing masses of fish bones, which Wendorf & Schild (1989, p. 819) interpreted as evidence of a shift to harvesting fish for later consumption. This might mark the beginning of a post-pleistocene type of foraging system with its shift away from large pleistocene mammals. At these sites the mammal remains were nearly indentical to those at Wadi Kubbaniya; the hartebeest, aurochs and dorcus gazelle were the only common mammals. But the hippo, which may have been more abundant in the Nile valley than Wadi Kubbaniya, turned up in these sites in small numbers (Wendorf & Schild 1989, p. 818). Some local variations are also seen in the faunal assemblages."
Wendorf, F. & R. Schild 1989. Summary and synthesis. In The Prehistory of the Wadi Kubbaniya, Vol 3: Late Palaeolithic Archaeology. Wendorf, R., R. Schild and A. E. Close (eds.), 768-824. Dallas: Southern Methodist University Press.