Evaluating the viability of remote sensing and gis techniques in the identification of potential fishing zones of nile tilapia fish on lake victoria

Abstract

Fishermen continue to underutilize potential fishery and marine resources. Lake surface temperatures and the chlorophyll-a concentration through remote sensing systems can be used as potential fishing zones. This study aims to determine potential fishing zones using geographic information systems through the distribution of Lake surface temperatures and the value of chlorophyll-a concentrations in Lake Victoria which is expected to improve the sustainability of fishing efforts. This research was conducted from May 2022-March 2023 using a geographic information system by extracting from Aqua MODIS satellite image and sea surface temperature overlay method with chlorophyll-a concentration. The results found the highest Lake surface temperature value was in October at 26.85°C and the lowest temperature was in July at 25.15°C. The highest average chlorophyll-a concentration in Lake Victoria was 19.37mg/m3 in October and the lowest concentration of chlorophyll-a in March was 6.29 mg/m3. The months of June, January, and October were observed to have the largest Potential Fishing Zones of Nile Tilapia Fish whereas December and July have the smallest potential fishing zones of Nile Tilapia Fish on Lake Victoria. The variations in LST between months could be influenced by factors such as seasonal changes, and ocean currents. In most months, high chlorophyll concentration levels, especially at the shorelines, could be attributed to river discharge, which could contain fertilizer and rainwater runoff. The PFZ of Nile Tilapia fish are largely identified close to the shores and to the islands situated in deep waters for all months on Lake Victoria because Nile Tilapia breeds well in shallow waters. These Potential Fishing Zones were validated with field Nile Tilapia fish cash data and 5 out of 10 sample locations were found to lie in the delineated zones. Generally, there are two major abiotic factors that influence the breeding life of Nile Tilapia fish in Lake Victoria i.e., LST and Chl_a. For all months on Lake Victoria, the PFZ of Nile Tilapia fish identified are generally close to the coasts and islands located in deep waters. The study revealed a cost-effective alternative strategy for identifying potential fishing sites for Nile Tilapia fish, which can help artisan fishermen cut fishing search times, costs, and effort while enhancing catch amounts. This method can be used with near real-time satellite-derived data to distribute Potential Fishing areas to fishermen for informed decision-making.