Sylvia Patricia Adelheid Jiménez Rosenberg

Fish larvae off the northwestern coast of the Baja California Peninsula, Mexico

The structure of the larval fish assemblage of the northwestern Pacific coast of Mexico is analyzed from zooplankton samples taken between 1998 and 2000 off northern and southern Baja California Peninsula. The 198 fish taxa identified reflected the faunal complexity reported previously for the area. Adult distribution patterns and reproductive behavior, added to the environmental seasonality and bathymetric characteristics of the coast, explained differences in the larval fish assemblage. Larvae of meso- and bathypelagics Vinciguerria lucetia, Diogenichthys laternatus, and Triphoturus mexicanus were the most abundant year round. Larvae of commercially important species, such as Engraulis mordax , Sardinops sagax , Merluccius productus, and Trachurus symmetricus, were also abundant during winter and spring, depending on the year and surveyed region. Adult distribution patterns and reproductive behavior, intra- and interannual environmental variability, and bathymetric characteristics of the coast all likely contributed to the differences in the larval fish community through space and time. For example, the abundance of temperate species in northern Baja California was relatively low when warm-water El Nino conditions prevailed in 1998 but increased during the cool-water La Nina period in 1999 and 2000. The results enhance knowledge of the community dynamics of fishes in an ecologically complex and commercially important region.

Fish larvae in Bahía Sebastián Vizcaíno and the adjacent oceanic region, Baja California, México

The taxonomic composition of the fish larvae assemblage of Bahia Sebastian Vizcaino and the adjacent oceanic region is presented based on oblique zooplankton hauls made during 12 oceanographic surveys between fall 1997 and fall 2000. In total, 186 taxa representing 71 families were collected. Myctophidae, Phosichthyidae, and Engraulidae were the most abundant during winter and Myctophidae, Merlucciidae, and Bathylagidae during spring. In summer and fall Phosichthyidae and Myctophidae were the most abundant. During 1999 and 2000, seasonal variability was identified in the area by the fish larvae composition, defining winter and fall as a low diversity period and spring and summer as a high diversity period. Interannual variability was detected with an El Nino event, with higher larval abundances of tropical and subtropical taxa, and a La Nina event, with high abundances of larvae of Engraulis mordax.