The primary objective of this study is to identify the key mechanisms affecting year-class variability in gag grouper. Other objectives include testing three possible mechanisms explaining the 2- to 3-week variation in settlement time exhibited by juvenile gag in sea-grass beds along the west Florida coast, including (1) spatial and or seasonal differences in spawning, (2) habitat-related differences in survival upon settlement, and (3) seasonal differences in transport. Our goal of discriminating among mechanisms accounting for geographic differences in settlement patterns directly increases our understanding of the connection between spawning grounds and transport to nursery areas.

    Our primary aim in this work is to differentiate among several factors that may influence spatial and temporal variation in recruitment of juvenile gag to sea-grass nursery grounds. This work relates directly to several other research areas our group has worked on for the last several years, including studies of reef-fish reproduction, reef-fish juvenile abundance, and eastern Gulf of Mexico oceanographic circulation patterns. Building on these previous projects we will add a comparative geographic study of spawning and settlement times for gag grouper, and we will complete a time-series data set that can be used in developing a fisheries-oriented oceanographic model of larval transport. It includes coupling annual variation in adult spawning distributions, juvenile abundance, and an otolith-based analysis of spawning and settlement times with physical data including wind, current-meter, and satellite-altimetry data. Our ultimate goal is to compare model transport predictions to otolith back-calculated times of spawning and settlement and cield-measured patterns of juvenile settlement and abundance across the west Florida shelf.