The research was aimed to study the condition of the seasonal ecosystem characters (water temperature, salinity, flow and depth) and the seawater temperature data from MODIS satellite, TRITON Buoy temperature, salinity, currents and depth of the hook in northern waters of Papua which is associated with fish catches of yellowfin tuna (Thunus albacores). The research method was based on a survey with emphasis on water parameters, ecosystems character which have a great influence of the fishing ground. The ecosystem variables that effecting fishing ground of yellowfin i.e. temperature, salinity, current and depth. Results from this study showed that the value of north Papua sea surface temperatures were relatively high during January and February, with the highest temperature in January 30.33 oC and relatively low in April with a temperature of 29.9 oC. In January - March, the salinity of the waters of north Papua 34-35.4 for each month and in depth, the current ranged from 4.4 to 39.1 cm/sec. The depth for setting the hook to catch yellowfin in a large numbers was mostly in between 177 and 219 meters, where temperatures ranged between 19.7 and 23.6 oC. Yellowfin monthly production in June to August and December 2010 to February 2011 showed a positive relationship between yellowfin catches and depth of water temperature (r = 0.544), depth of the hook (r = 0.533), salinity (r = 0.403) and current (r = 0.537). The results of multiple regression analysis showed a strong relationship to each variable parameters of temperature, depth, salinity and current (r = 0.611) of the catch.