Hydrodynamic connectivity and dispersal patterns of a transboundary species (Pagellus bogaraveo) in the Strait of Gibraltar and adjacent basins

Abstract

The blackspot seabream (Pagellus bogaraveo) is a benthopelagic fish species highlyappreciated by consumers and an important target of the Spanish and Moroccan fish-eries in the transcontinental waters of the Strait of Gibraltar area. It is also one of themost exploited resources of the region, which has led to a situation of overex-ploitation and a notable drop of catches. To gain insight into the sustainability of thisresource and certain patterns of the spatial adaptation of the species, a high-resolution circulation model coupled to a Lagrangian tracking module has beenemployed to investigate the dispersal pathways of blackspot seabream, using eggsand larvae (early-life-stages, ELS) as purely passive particles advected by currents.Several spawning scenarios consisting of different spatial (depths and sites) and tem-poral (tidal phase and strength) initial conditions have been analyzed to identify themost likely pathways of ELS dispersion. Eastward transport by the Atlantic Jet exitingthe Strait of Gibraltar is the most influencing process in that dispersion. Regardingtemporal fluctuations, fortnightly tidal modulation is the prevailing factor to deter-mine the horizontal paths of the ELS, spring tides being the cause of the greatestscattering of propagules. Spawning depth in the Strait of Gibraltar is a critical condi-tion, as revealed by the model sensitivity tests. Potential implications of the results ofthe study to improve the assessment and management of this species are discussed.