Movements and habitat prefernce of Cichlids in the upper Zambezi River

Abstract

Abstract by author:

In October 1999, a study tagging 16 cichlids with radio transmitter was conducted in the Zambezi River near Kalimbeza Island (eight three spot tilapia- Oreochromis andersonii Castelnan, 1861, seven pink happy Sargochromis giardi Pellegrin, 1903 and one humpback largemouth Serranochromis altus Winemiller and Kelso Winemiller, 1990). The fish were caught on rod and line, anaesthetized and tagged with external transmitter (n=12) and implant able (n=4) transmitter before being released into the river. Range tests showed that boat tracking could control the main river. The tagged fish were positioned by manual tracking until 1 March 2000; the study covered the period of increasing water flow towards the rainy period and flooding. Nine of the tagged fish showed a downriver movement immediately after release, believed to be a behavioral reaction to catch, handling and tagging. Eleven fish were released 350m to 1000m from the catch site. Only one (9 percent) was recorded later at the catch site, indicating that displaced individuals of three spot tilapia and pink happy do not show homing behavior to the catch site. Five fish were released at the catch site, and four of these (80 percent) were recorded later at the catch site. The three spot tilapia were located in the main river on average 67 percent, backwaters 13 percent and mouth of backwaters 20 percent of the tracking. The pink happy were located in the main river on average 71 percent, backwaters 25 percent and mouth of backwaters 4 percent of the tracking