Abstract: Duration of Sri Lankan fishing fleets has been reported as 2-4 weeks to catch the average target of approximately 2 tones per trip. However, low catch rates are caused by the uncertainty of catches due to lack of technology available to find fishing grounds. This study is focused on the impact of temperature and ocean currents at the depth where Yellowfin tuna (YFT) has been caught. Currents and temperature data at different depth levels were obtained from Copernicus Marine Environment Monitoring Service (CMEMS). Longline tuna catch datasets were obtained from the Department of Fishery, Sri Lanka.