Fish migrations in Lake Edward-Ishasha River water systems in Virunga and Queen Elizabeth National Parks

Abstract

This study investigated the fish migrations in Lake Edward – Ishasha River water systems. The main objective was to examine the migration patterns of clarias gariepinus in Lake Edward and its adjacent water systems. The study intended to identify migratory habitats and spawning grounds for C. gariepinus, ascertain the fish migration periods and estimate the extent of migrations in the water systems. The study took into account the environmental factors (dry/wet seasons and rainfall) and measured limnological parameters to identify the parameters that influence the migration and spawning. The migration patterns were examined using the mark-recapture techniques. Fish were sampled twice seasonally with beach-seines in July – August; September – October 2011; February – March and; April – May 2012. A total of 1,103 C. gariepinus specimens were tagged with external T-bar Anchor tags and released at four estuarine sites. Fish were recaptured in different habitats using beach seines, gillnets, hooked lines, traps (baskets), spears and machetes. Relocations of 115 C. gariepinus were determined and spawning condition examined between September 2011 and December 2013 within the lake and its adjacent water systems. The study identified the river channels of Ishasha, Ntungwe, Nchwera, Bizibibi and Cyahulwa Rivers as migratory routes connecting C. gariepinus that migrate between the lake and the rivers’ respective marginal wetlands. Bizibibi and Kayanza – Kyondo littoral zones; Kihera and Bucundezi river mouths; Ntungwe river channel; Cyahulwa, Kinyozo, Ntungwe and , Namba Munana marginal wetlands were identified as the key spawning grounds of C. gariepinus, in the investigated water systems.