Influence of monsoonal variability on the potential recruitment of Sardinella lemuru in the Philippines

An important pelagic fishery in the southern Philippines is of the tropical Bali sardine, Sardinella lemuru (Bleeker, 1853) which is a year-round spawner having peak spawning during the northeast monsoon (NEM) months. To understand the high variability in sardine stocks, the dispersal of sardine larvae from identified spawning areas until the estimated recruitment age of 60 days was simulated for six years with model runs every five days at three depth layers. The experienced ambient sea surface temperature and chlorophyll-a based on monthly composite remote sensing data was also recorded based on larval tracks. Larvae released during the peak spawning NEM months experience the lowest retention but high chlorophyll-a and lower temperatures. This presents trade-offs between advection and starvation mortality. Interannual differences between NEM-spawned larvae show that during higher reported catch years, larvae experience higher retention and lower temperatures. The differences in potential recruitment are assessed based on the seasonal and interannual variability of circulation, rainfall, chlorophyll-a, and temperature in the region.