Functionality evaluation of the Xikundu fishway, Luvuvhu River, South Africa

Abstract

The Xikundu fishway, in the Luvuvhu River near Thohoyandou, was monitored for 23 months in 2004–2006. Adults and juveniles of 60% of the expected fish species were collected in the fishway, and two major upstream migrations occurred. Most Labeo and Chiloglanis species migrated in late summer and autumn, possibly to seek refugia, whereas Barbus and Labeobarbus species moved upstream in spring, possibly for spawning. There were strong diel differences in upstream movement, with most species moving at night, as well as interannual variation among species, possibly reflecting differing recruitment. Although some fish moved both up- and downstream through the fishway, the fishway functioned poorly, as significantly higher numbers of fish were only occasionally able to ascend the full length of the fishway when its discharge and turbulence were low (>70 W m⁻³). Further experimental research on appropriate turbulence, water velocity and fishway design for South African fishes is recommended. For future field evaluation, sampling of the population immediately downstream of the weir and fishway is recommended to enable a more quantitative evaluation.

Keywords:

• effectiveness
• environmental cues
• fishway monitoring
• hydraulics
• migration