Fish species composition in the littoral zone of the Kavango floodplain river, Namibia

Abstract

Littoral fishes in the marginal zones of the Kavango floodplain were sampled using a seine net between March and October 2011. Juveniles of the three commercially important species; Oreochromis macrochir (40.3%), Oreochromis andersonii (19.3%), and Tilapia rendalli (10.2%) were among the five most important species in the littoral zones. This demonstrates the potential use of the littoral zone as a nursery ground for feeding and refuge. Juvenile fish densities of O. macrochir, O. andersonii, and T. rendalli showed spatiotemporal variation across seasons. Juvenile fish densities were relatively low in winter (June –August) and during the dry seasons (September – October). The attributing factors for these observations were linked to relatively low water temperatures (17oC) during winter and high recruitment off the floodplain into the main river channel as the fish grew to mean length of about 70 to 80 mm in size. For the sustainability of the fishery for O. macrochir, O. andersonii, and T. rendalli which are commercially important species, seine netting in littoral of the Kavango floodplains should be discouraged to avoid recruitment overfishing. This management measure will ensure that fish are not caught at a smaller size before they mature and recruit into the fishery.