Larval fish assemblages and circulation in the Eastern Tropical Pacific in Autumn and Winter

Abstract

In this work, we linked larval fish assemblages with water masses and circulation in the Eastern Pacific off Mexico, during autumn 2005 and winter 2007. Four assemblages were defined. (i) The Transitional assemblage, with the lowest mean larval abundance and dominated by tropical mesopelagic Vinciguerria lucetia and Diogenicthys laternatus. It was associated with modified California Current Water in winter and with modified Surface Water in autumn. (ii) The Coastal-oceanic assemblage was found off Cabo Corrientes, with high larval abundance, and dominated by Bregmaceros bathymaster; part of this assemblage was trapped by coastal cyclonic eddies. (iii) The Tropical A assemblage was associated with Surface Water. It had the highest abundance and richness, and the largest number of dominant species (e.g. D. laternatus, Auxis spp.); it covered a wider area in winter than in autumn. (iv) The Tropical B assemblage, distinguished by the highest abundance of V. lucetia, was present only in autumn; it was associated with overall anticyclonic circulation of warm Surface Water. The agreement between larval fish assemblage distributions, water masses and mesoscale dynamics indicates that the formation and permanence of assemblages depends on the interaction of spawning strategies of different species with large-scale and mesoscale processes.