By Kerry Brink
Freshwater migratory fish do not only migrate upstream and downstream for their survival, but can also migrate laterally onto floodplains. The term “lateral migration” in this context refers to fish moving between the floodplains and main tributaries and rivers. In the Zambezi River, an impressive river flowing through nine countries in Southern Africa, fish species that migrate laterally onto floodplains is a common sight. In the rainy season thousands of individuals move between the rivers and floodplains. Many of the >31 fish species embarking on their annual migrations onto the floodplains are migrating to spawn and/or to avoid predation of large predators, such as the tigerish.
In one of the major river systems in the Zambezi catchment worth mentioning is the Luangwa River. The Luangwa River, is the largest free-flowing river in Southern Africa, with a high biodiversity of aquatic species and wildlife. It is home to one of the highest concentrations of hippopotamus in Africa and to the newly identified endemic killifish species (Notobranchius boklundi), which exists within the floodplains. The Luangwa is also one of the many rivers that are mapped in the global assessment of free-flow rivers by WWF and McGill University – a fantastic overview of free-flowing rivers and their value: http://www.free-flowing-rivers.org/about.
For more information about fish passage and free-flowing rivers in Africa you can download the book: From Sea to Source 2.0.
Photo’s from the Luangwa River (c) Bruce Ellender