Early in 1957, the Section of Hydrology and Fisheries Biology of the Philippine Bureau of Fisheries started a program for reevaluating the trawl fishery in Manila Bay to compare the results obtained from previous studies by Warfel and Manacop (1950). This paper is a preliminary report covering the first three-year period from 1957 through 1959 based primarily on the data gathered by the technical staff of the above-mentioned Section who joined the fishing trips of commercial vessels fortnightly, each trip lasting from 3 to 5 days.
The otter trawlers were primarily of the design and type previously mentiond by Warfel and Manacop (1950). It was found that there has been a slight increase in the number of fishing vessels operating in Manila Bay during the period under review with a resulting decrease in the total average catch. A classification of fish caught, based primarily on the commercial method, was used in this study, classifying the catches into hoya, shrimp, squid, slipmouth, lizard fish, and miscellaneous group. It has been shown that there has been a decrease in the catch per hour drag from 1957 to 1959. There has been noted also a direct correlation between the boats operating in the Bay and the seasons of the year.
It is believed that the Manila Bay trawl fishery has reached its maximum development and this led to a change of gear for catching pelagic fish outside Manila Bay, namely, the haswigan and the introduction of twin engines into larger trawlers to enable them to catch more pelagic species in the Bay. Analyses of the catch of four fishing vessels representing typical size groups support the foregoing conclusion.