This has decreased primary productivity by about 20%, and decreased fish yields as a result (Verburg et al., Water levels and surface areas of some large, shallow African lakes (such as Lakes Chilwa, Bangweulu and Chad) fluctuate with changes in ENSO (Jul-Larson et al., These fluctuations are mirrored by changes in fishing activity and catches (Allison and Mvula, 2002). Stream temperatures in this basin have been increasing steadily since 1992. It has been argued that few North Atlantic fish species will be as intensely affected by climate change as Atlantic salmon (Stenseth et al.,