Bottom trawl fisheries are one of the important inshore fisheries in Taiwan, but its landing is decreasing and demersal fish resources are exhausted from1980.So, to improve definitely the fishing condition for trawl fishery, it is necessary to investigate comprehensively the recent situation of trawl fishery. This studies in view of investigate the biological ecology, spawning period, distributions of larva and fishing ground of the main economic fishes in the southwestern waters of Taiwan, and to determine accurately the geographical position of spawning ground by the scientific method, and then it will be a reference basis in future for the fishery resources estimate, conservation, management and fisheries administration decision-making.