Spawning of small pelagic fishes in Bahia Magdalena, Baja California Sur, Mexico, at the beginning of the 1997-1998 El Nino event

A study of the seasonal abundance of planktonic eggs and larvae of small pelagic fishes, and relationships of egg and larval abundances with sea surface temperature and zooplankton biomass in Bahia Magdalena, Baja California Sur, Mexico, a subtropical lagoon, was done during the first year of the 1997-1998 El Nino event. Sardinops caeruleus and Scomber japonicus spawned primarily in winter, when sea surface temperature and zooplankton biomass were lowest (19.8-21.0 degreesC; 100-300 ml 1000 m(-3)), while Anchoa spp. and Opisthonema spp. spawned predominantly in late spring, when the sea surface temperature and zooplankton biomass were increasing to their summer maxima (>21.0 degreesC; >300 ml 1000 m(-3)). During the warm, El Nino years of 1983 and 1997, the egg and larval abundances of Opisthonema spp., a taxon of tropical affinity, increased, while those of Sardinops caeruleus, a transitional, California Current species, diminished drastically. This decline for S. caeruleus probably reflected a shift in the spawning distribution of the adults. Diminished commercial catches during 1997 in Bahia Magdalena, coupled with significantly increased catches in the north, off Ensenada, Baja California, provide supporting evidence. (C) 2001 Academic Press.