Introduction

Lake Victoria is located in Africa, it is the largest lake in Africa by surface area, the world's largest tropical lake, and the world's second largest freshwater lake by surface area. Its catchment area covers 169,858 km², and it has a shoreline of 7,142 km. The lake was formed about 400,000 years ago when westward-flowing rivers were dammed by an upthrown crustal block. The lake went through changes ranging from its present shallow depression, to what may have been a series of much smaller lakes. Lake Victoria receives 80 percent of its water from direct rainfall and is drained solely by the Nile River near Jinja, Uganda, on the lake's northern shore. The lake is considered a shallow lake considering its large geographic area with a maximum depth of approximately 80 meters and an average depth of 40 meters. Lake Victoria used to have a rich diversity of fish, including many endemics, but a high percentage of these became extinct in the 1940s. The main group in Lake Victoria is the haplochromine cichlids with more than 500 species, almost all endemic. The lake and its wetlands have a large population of Nile crocodiles, as well as African helmeted turtles, variable mud turtles, and Williams' mud turtles.