Ecological implications of Rastrineobola argentea (omena) fishery: A rapid assessment of bycatch diversity at Dunga Beach, Lake Victoria, Kenya

Abstract

Rastrineobola argentea (omena) is the second most important species in the fisheries of Lake Victoria after Nile perch. However, its fisheries have negative impacts on the ecology of the lake especially because of the high numbers and diversity of bycatch resulting from the fishery. This study conducted a rapid assessment in Dunga beach in Kisumu, Kenya to identify and quantify the bycatch and to collect information on the fishermen’s perceptions of the bycatch from the omena fishery. All the boats reported bycatches of different species and different sizes. The bycatches comprised of Lates niloticus, Haplochromis spps, Clarias gariepinus, Protopterus aethiopicus, Synodontis. The smallest bycatch recorded was Haplochromis spp (3.3 cm; 3g) while the largest fish bycatch was Protopterus aethiopicus (1.5 m; 2.4 kg). Other bycatch recorded were freshwater shrimps and molluscs. 80% of the fishermen suggested the provision of alternative livelihoods as a measure to reduce the pressure on omena fishery while 12% recommended stricter rules on gears implemented. A total of 99% of the fishers reported that they do not return bycatch into the lake but rather sell them together with the main catch (omena). The implications of this on the ecological functioning of the lake is predicated on the negative impacts on the trophic interactions in the ecosystem