Assessment of Fish Species Composition and Relative Abundance in River Sene: A Case Study at Kpatsa Akura in the Sene District, Ghana

Abstract

Background: Inland fisheries play a vital role in food security, livelihoods, and biodiversity conservation, yet their ecological and economic contributions remain under-researched, highlighting the need to assess fish assemblages and fisheries dynamics in the River Sene for sustainable management. Aims: This study aimed to assess fish species composition, richness, abundance, relative importance, and diversity in the Sena River at Kpatsa Akura, and to identify the major fishing gears and target species exploited by local fishers. Study Design:  The study adopted a field-based descriptive survey and fish catch assessment approach. Place and Duration of Study: The study was conducted at fish landing sites in Kpatsa Akura along the River Sene in the Sene District of Ghana, between November 2019 and April 2020. Methodology: Monthly fish landing data were collected from artisanal fishers operating along the River Sene. Fish specimens landed at the sampling site were identified using standard taxonomic identification keys, counted, weighed, and measured for total length. Data on fishing gears and mesh sizes used by fishers were also recorded. Species composition, frequency of occurrence, relative abundance, and the Percentage Index of Relative Importance (%IRI) were calculated. Species diversity was estimated using the Shannon–Wiener diversity index (H'). Results: A total of 6,892 individual fish representing 20 species and 15 families were recorded during the study period. Ten species were consistently present throughout the six months of sampling, indicating stable occurrence within the river system. The family Cichlidae recorded the highest number of species. Lepidarchus adonis was the most dominant species, accounting for 72.55% of the total catch by number, 49.28% by weight, and 35.55% of the total %IRI. Coptodon zillii was the second most important species, contributing 15.60% of the total catch and 34.57% of the total %IRI. April recorded the highest fish landing (3,067 individuals), while January recorded the lowest (240 individuals). The overall Shannon–Wiener diversity index (H' = 1.08) indicated moderate fish species diversity with dominance by a few species. Seven major fishing gears were identified, including cast nets, gillnets, purse seines, traps, hook and line, and “Atidza,” each targeting specific fish families. Conclusion: The River Sene fishery is characterised by moderate fish diversity and strong dominance by a few commercially important species, particularly L. adonis and C. zillii. The dependence on a limited number of species, coupled with the use of selective fishing gears, may increase the vulnerability of the fishery to overexploitation and environmental changes. The findings provide important baseline information for fisheries management, conservation planning, and future ecological monitoring of the River Sene and related freshwater systems in Ghana.