Potential dispersion of reproductive products and larval stages of abalone (Haliotis spp.) as a function of the hydrodynamics of Bahia Tortugas, Mexico

Field observations of currents and water mixing were made in autumn 1996, at four coastal sites close to Bahia Tortugas, on the central part of the Baja California Pacific coast, to evaluate the influence of the hydrodynamics on the transport of abalone larvae (Haliotis spp.). Current measurements and full-scale Lagrangean experiments on surface-water transport were carried out during the main spawning season of this genus in the area. Tidal currents seem not to be the dominant factor, but instead both, wind- and wave-driven currents appear to be the most important factors for larval transport in this coastal area. Additional echo sound and aerial surveys confirmed that the reef topography and kelp beds attenuate current velocity. The hypothesis of larval dispersion is that during a typical 3- to 5-day pelagic period, larval and postlarval stages might be retained primarily in areas close to parental reefs. Flushing time in Bahia Tortugas was evaluated as five semidiurnal tidal periods. Sufficiently intensive currents at the mouth of the bay (up to 25 cm/sec) may complicate larval interchange between northern and southern vicinities of the bay.