This study uses the gag grouper as a representative for the plethora of reef fish species in the BBR, due to its economic importance as a top-level predator and the scarce knowledge of its eary life stages. Adult gag spawn on offshore reefs along the continental shelf break each Spring (Feb - April) (Coleman et al., 1996). During their pelagic stage, gag larvae are transported across the shelf until eventually settling as juveniles in the seagrasses of the coastal BBR waters 30-60 days later (Koenig and Coleman, 1998). However, while decades of ichthyoplankton surveys in the NEGOM have found Serranidae to be one of the most abundant families taken, the subfamily Epinephelinae have not been among those found (Keener et al., 1998). The physical mechanisms responsible for transporting these larvae remain unkown.

The role of upwelling dynamics and Ekman transport in distributing passive particles into near-coastal waters are assessed in this study. The main tool that will be used is a very high-resolution numerical ocean model. The Regional Ocean Modeling System (ROMS), configured at 1/120°, is nested one-way within the Gulf of Mexico HYCOM (www.hycom.org) . The domain extends north of 28°N and to the east of 86.75°W, a region that encompasses the entire BBR and the local shelf break. Simulations are run for 2004-2010, corresponding with a period of gag sampling efforts in the BBR. Using output from the physical model, we simulate the motion of particles within the local shelf circulation using a Lagrangian particle tracking model (LTRANS). Behavioral patterns are then included into the particle tracking algorithm, allowing the simulated particles to be used as proxies for gag larvae.