Abstract

This study examines population connectivity across the Gulf of Mexico (GOM) basin through larval transport. Understand-ing connectivity between regional populations is important for fishery management. Satellite tracked near-surface drifters from two large Minerals Management programs in the northern GOM were used to represent larval spread across the basin from the north. Archived data from the Hybrid Coordinate Ocean Model with a Lagrangian algorithm was used to determine spread from the south (Campeche Bank). Both drifter and model data were employed on the western boundary to examine continen-tal shelf larval transport connections between the US and Mexico. Oceanography of the GOM basin is dominated by the Loop Current and its large spin-off eddies characterized by strong currents. Reef fish commonly have a planktonic larval duration (PLD) of about one month from spawned egg to juvenile settlement. The question of whether currents in the basin are sufficiently strong and directed to transport larvae to distant settlement areas during the PLD is addressed. Connectivity across basin does occur, but is weak. In general, it is sufficient to homogenize the gene pool but insufficient to influence manageable population size. There is seasonal transfer of larvae across the Mexican/Texas border on the basin’s western continental shelf. During summer and primary reef fish spawning season, the flux is from Mexico to Texas. During the remainder of the year, the flux is from Texas to Mexico. Ocean dynamics at the border inhibit strong connectivity.