Studies on the plankton of Manila Bay were started in April 1957 and are being continued to the present as a part of the researches on the life history of fishes of commercial importance in Manila Bay.
Recently, in conjunction with the exploration for tuna of the M/V “Malasugui”, plankton collections were made during the fishing trips for tuna. In addition, plankton collections were made on board a bagnet boat (basnigan) in Manila Bay, a fishing gear for pelagic fishes which is operated during the dark phase of the moon.
The present paper is based on data collected during the monthly hydrographic investigations of Manila Bay. It describes the catching power of plankton nets and conventional methods and techniques employed in the research work and a comparison of results based on two methods of determining quantities of plankton gathered.