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Larval fish abundance off the coasts of the central portion of the Mexican Pacific was studied during a year cycle. Zooplankton samples were collected during 11 sampling cruises carried out between December 1995 and December 1996 using a bongo net. A total of 63,342 larvae were collected. The most abundant families were Bregmacerotidae 94.6%, Eleotridae 1.19%, Sciaenidae 0.67%, and Engraulidae 0.64%. Abundance values were significantly higher (P < 0.005) at near-shore stations, suggesting a potential ecological use of adjacent coastal environments as nursery areas. Fish larvae were most abundant during January-May, a period with the lowest average sea temperature, which is related to the seasonal influence of the California Current (CC). In these months, advective processes are active along the outer shelf favoring upwelling of colder, relatively nutrient-richer waters which in turn allow an overall local increase of zooplankton activity and populations. The high variability of abundance values in the surveyed area suggest episodic, localized processes enhancing the local productivity. Lowest abundance occurred in October-December, when the CC is weak and the area is influenced by tropical oligotrophic waters. Highest abundance values were consistently found at nearshore stations, this is probably related to (1) the extraordinary dominance of the coastal species Bregmaceros bathymaster and (2) the inshoreward transport of larvae into potential nursery areas. B. bathymaster was the most abundant larvae during the entire survey period. It is suggested that this species has a year-round breeding cycle, with moderate month-tomonth but sharp seasonal variations. The absence of adult individuals of this species in the surveyed area suggest that it probably spawns in the ocean and its larval stages are transported inshorewards into potential nursery zones. Inglés

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