Spatio-Temporal Diversity and Abundance of Fish in the Little Ruaha River Catchments, Iringa Tanzania

Abstract

Fish are an important component of Tanzania's aquatic biodiversity and contribute to the national economy. However, there has not been a sufficient evaluation of the spatial-temporal distribution of fish in the Little Ruaha River catchments. This study determined the spatiotemporal diversity and abundance of fish and generated information on the spatial distribution of fish across the catchments. Fish samples were collected during the dry and rainy seasons at three sampling sites (upper reach, middle reach, and lower reach) using gillnets of 76.2 mm mesh size. Using the Shannon diversity index, we computed the diversity of fish in different habitats and seasons. We used the Kruskal-Wallis and Mann-Whitney tests to determine the differences in fish diversity and abundance between habitats and seasons. We captured a total of 250 fish individuals from five different species. The fish species diversity and relative abundance were higher in the lower reach compared to the upper reach. The relative abundance of fish was statistically different (p = 0.01) between habitat and seasons. However, there was no significant (p = 0.3) difference in fish diversity between habitats and seasons. Oreochromis and Clarias were the most common species across all habitats. Management of river basins should integrate fisheries activities for integrated river basin management.