KAGONDU NJAGI MARY Achieng' sifted through her catch of silver cyprinid fish, sorting them into gunny sacks and carrying them to the weighing stand at Kogwang' Beach, on the Kenyan shore of Lake Victoria. Achieng' had caught the fish the night before, using a solar-powered light to lure them into her nets. The 500-kg (1,100-lb) haul would earn her 50,000 Kenyan shillings ($450) - enough to keep her family going until she next went out again on the lake a week later. Before she got the lamp two years ago, Achieng' had to stock her stall in Kendu Bay with whatever she…