Hydroacoustical evidence of autumn inshore residence of the pelagic red crab Pleuroncodes planipes at Punta Eugenia, Baja California, Mexico

Abstract

The red crab Pleuroncodes planipes (Stimpson, 1860) dominates the micronektonic fauna in the nearshore waters of the Pacific coast of Baja California, Mexico, and is a dominant functional component of the upwelling ecosystem in the California Current Dense adult surface swarms have been found inshore during the first half of the year in coastal upwelling regions near Baha Magdalena (24N) (Fig. This seasonal inshore-offshore model of adult distribution is coupled to an offshore passive larval drift of the zoeal and postlarval stages from Baha Magdalena after the peak of reproductive activity in February-March. This larval drift of the red crab is promoted by surface Ekman transport, indicated by positive upwelling indices (Gmez-Gutirrez & Snchez-Ortz 1997). The California Current carries the early postlarval stages far to the southwest, up to 130W. Ovigerous females have been reported in the open ocean, but their contribution to the overall population reproduction is small in comparison to that from the coastal areas Several studies indicate how a semipermanent eddy, which develops in autumn near Punta Eugenia (Fig.