Description: The present paper is based on a study conducted in the Philippines from November 1979 to April 1980. The study was part of a national research project on the situation of small-scale fishermen in San Miguel Bay, an important fishing ground in southern Luzon. The purpose of the paper is to assess the present state of the fishery in San Miguel Bay and its impact on the bay's resources. Thus, it is intended to give a preliminary answer to the question of a possible overfishing in the San Miguel Bay. In the introduction, the paper reviews some of the difficulties encountered when concerned with the mangement of tropical fisheries. This is followed by a description of the fishery in San Miguel Bay. Confined to trawlers and gill-netters, the fishing vessels are classified and their mode of operation is described. Estimates are given on the average number of boats per day fishing in San Miguel Bay. Statistics on the landings from the bay are presented and the reliability of their sources is discussed. The catch data are summarized, adjusted, and thus utilized to estimate total annual catches for the various fishing gears. Based on the Swept Area Method, a value is computed of the fishing mortality (F) inflicted on the stocks of San Miguel Bay. The procedure of the method is described and its basic assumptions are critically reviewed. Furthermore, the seasonality is shown in the landings of trawlers and in the relative abundance of some important species or groups of species over the period of one year. The compensation effect is demonstrated that the catches of shrimps have on the income of fishermen during the months of generally low volume of fish catches. Finally, the findings of the paper are discussed. It is tried to assess the reliability of the computed F. The question is examined, whether the calculated result is in accord with other observations pointing in the same direction. Suggestions are made how to improve these preliminary results.