Assessment of community composition and welfare of fish in lake Mulehe in Kisoro District Southwestern Uganda

Abstract

Besides Lake Victoria, minor lakes including Mulehe in Kigezi play a fundamental role in providing fish for nutrition and livelihoods of the riparian communities. Despite the importance, minor lakes are constantly being restocked; suggesting an unconducive environment for the introduced fish. Besides, restocking alters the species composition that may require different fisheries management approaches. As such, the study examined water quality parameters, the fish species diversity and welfare in Lake Mulehe. The water quality parameters were measured in and offshore the lake at different depths over a 24-hour period, fish species were determined from the catches landed, the weight and length of selected individuals of different species determined and used to calculate the condition factor. The results revealed that the average for DO, pH and temperature were 8.5, 7.7 and 21.8℃ respectively (Table 4.1). During the study, three fish species were recorded namely Haplochromis species (Haplochromines), Clarias liocephalus (mud fish) and Oreochromis niloticus (Nile tilapia) landed from the lake. The catches were dominated by Haplochromis spp, followed in descending order by O. niloticus and C. liocephalus. The number of species recorded was significantly lower than that obtained during previous studies which is attributed to selective fishing by the fishermen for species of great commercial value. The condition factors for the three species were 1.128, 1.143 and 0.58 respectively, which revealed that the fish exhibited negative allometric growth. This pattern of growth could be as a result of the low water temperatures in the lake. The condition factor of the species recorded is below 3, the condition factor for fish isometric growth. Therefore to make certain of all fish species present in the lake, the study recommends experimental fishing in addition to what fishermen land from the lake so as to obtain all the fish species present in the lake. To better understand the availability and survival of fish, other water quality parameters besides those included in the study should also be assessed.