Movements and habitat utilization of three cichlid species in the Zambezi River, Namibia

• Published in: Ecology of freshwater fish Vol. 10; no. 4; pp. 238 - 246
• Main Authors: Thorstad, E. B., Hay, C. J., Næsje, T. F., Økland, F.
• Format: Journal Article
• Language: English
• Published: Copenhagen Munksgaard International Publishers 01.12.2001
• Subjects: Freshwater; homing; movement; Oreochromis andersonii; radio telemetry; Sargochromis giardi; Serranochromis altus
• ISSN: 0906-6691; 1600-0633
• DOI: 10.1034/j.1600-0633.2001.100406.x

– During 5–7 October 1999, 16 cichlids (30.5–51.0 cm) were tagged with radio transmitters in the Zambezi River in Namibia (eight threespot tilapia Oreochromis andersonii, seven pink happy Sargochromis giardi and one humpback largemouth Serranochromis altus). The main objectives of this pilot study were 1) to assess whether and how telemetry can be used to follow the movements of larger cichlids in the upper Zambezi River and 2) to study the movements, habitat preferences and homing behavior of three cichlid species important for subsistence and trophy fishing during a period of increasing water flow towards the rainy period. Nine fish showed a downriver movement immediately after release, believed to be a behavioral response to catch and tagging. From 11 October, only small‐scale movements were recorded. Average total distance moved from 11 October to 1 March was 375 m (range=1–1150) for threespot tilapia and 1276 m (range=540–1990) for pink happy. The farthest position compared to the position held on 11 October was on average 220 m away (range=0–500) for threespot tilapia and 538 m (range=20–1500) for pink happy. Displaced individuals did not show homing to the catch site. The threespot tilapia were, on average, located in the main river during 67% of the tracking surveys, in backwaters during 13% and in mouth of backwaters during 20%. The pink happy were, on average, located in the main river during 71% of the tracking surveys, in backwaters during 25% and in mouth of backwaters during 4%.