The sun is halfway up over Kusa Bay, where the brown waters of Lake Victoria lap at the parched Kenyan savanna. A Luo fisherman poles his plank canoe into an opening hacked through the reedy, papyrus-clogged shallows. Six of his comrades grab the bowline and begin a rhythmic chant as they drag the vessel to shore. "Harambee, harambee, harambee, ayaaah," they sing out as they lean into the task, "together, together, together." The women on the bank laugh, awaiting the catch, their baskets and bright plastic tubs bobbing on their heads.
Yet a casual glance into the dozen canoes beached on the mud reveals hardly any fish at all. Moving among them, Peter Ochumba inspects the meager catch stacked on the floor of each boat. Two dozen ten-inch Nile tilapia. A few Nile perch that aren't much larger. A bucket of haplochromine cichlids--little fish, two to four inches long, that used to dominate these waters. One labeo, or ningu as it's known locally, a small carplike delicacy whose abundance formerly made this village prosperous.
Ochumba is a limnologist--a freshwater specialist--with the Kenya Marine Fisheries Research Institute (KMFRI). He understands better than most why his fellow Luo and tens of thousands of other fishermen around the lake have so little to show for their night's labors. From the bottom of a boat he picks up the most publicized suspect, a Nile perch. Had it not been caught as a foot-long juvenile, this fish might have grown to a six-foot, 200-pound giant, mostly by gobbling up the smaller fish that are these fishermen's livelihood.
No other freshwater fish has received as much bad press as the Nile perch--Lates niloticus in the language of taxonomy, "voracious alien predator" or "fish of doom" in the language of the British tabloids. Since its introduction by British colonials in the mid-1950s, the perch has exploded in number, apparently wiping out fully half the 400 species of haplochromine once native to the lake. These little fish not only form part of the food chain for millions of Africans around the lake, they are also one of the natural wonders of the world--a case of evolution in such frenzied overdrive that they've appeared on the prestigious cover of Nature. Western scientists have long flocked to Victoria to study the haplochromines' legendary diversity. One of them, Les Kaufman, chief scientist for the New England Aquarium's Edgerton Research Laboratory, has termed the haplochromine loss "the greatest vertebrate mass extinction in recorded history."
But there's mounting evidence that the Nile perch may only have rendered the coup de grace. The whole lake is dying, and humans more than perch are the culprits.
