Tuna resource is abundant in central-western Pacific Ocean. Moreover, the easternwaters off Taiwan are noted as the migrating route and potential spawning grounds forPacific bluefin tuna. To determine the spatial and temporal distributions of tunas larva,especially for bluefin tuna, yellowfin tuna and bigeye tuna; it is an important andessential study in tuna fisheries. After the following studies as: (1) collecting the fisheriesstatistics data, (2) measuring the fork length of tunas, (3) examining the geographicaldistribution of tunas larva and (4) analyzing the spawning biology of main tuna species,then with the knowledge of the oceanography, i.e., drifting of current and characteristicsof TS, the potential spawning grounds and fluctuations of the recruitment for tunas canbe inferred.