No abstract

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 Niño conditions prevailed in 1998 but increased during the cool-water La Niña period in 1999 and 2000. The results enhance knowledge of the community dynamics of fishes in an ecologically complex and commercially important region.

We report the presence of striped marlin larvae in coastal waters of the mouth of the Gulf of California, collected during seven oceanographic cruises during 1990 to 1993. From 169 sampled stations, 30 produced a total of 68 larvae of 2.4–30.5 mm total length. Most of the larvae were about 3 mm, indicating a recent spawn. The sea surface temperature at the sampled stations ranged from 19.4°C to 32.0°C, but larvae were caught at stations with temperatures between 27.8°C and 31.5°C. These results clarify the existence of a spawning area of striped marlin in the eastern Pacific, located closer to the coast than previously believed, during several months of the year.

The first check-list of marine fish larvae from the coasts of Jalisco and Colima (Mexico) is presented. The fish larvae were sorted from zooplankton samples collected with Bongo net during 11 oceanographic surveys between December 1995 and December 1996. A total of 102 taxa belonging to 50 families and 80 genera were identified. The families with the most number of species were Cynoglossidae, Carangidae and Paralichthydae. This collection represents the first step to future research on the biodiversity of fishes of this tropical region that has been little studied. The ichthyoplankton collection was catalogued and deposited in the Centro de Ecología Costera of the Universidad de Guadalajara, Mexico.

The aim of this study was to investigate the potential effects of the harvesting season and fish size on the final quality of cage farmed gilthead sea bream (Sparus aurata). Morphometric analysis, fat stores estimation, fillet composition analysis, fillet fatty acids profile determination and sensory analysis were carried out on a commercially-sized cage farmed gilthead sea bream (Sparus aurata L.) population in April, June, July and November. Both season and size had a significant effect in morphometric characteristics. The most pronounced size effect was the change of fish shape, becoming rounder with fish growth, the increase of filleting yield and condition index. An increase of both peritoneal and perivisceral fat was observed in summer months. In general size had little effect on muscle composition. A significant size effect was observed in the fillet lipid content, which increased with it. Fillet lipid content was unexpected lower in the warm period (June-July). This can be possibly attributed to feeding restrictions that may have occurred, due to anoxic incidents related to high temperatures.Slight seasonal differentiations occurred in the muscle fatty acids. No significant differences were found in the organoleptic characteristics of the two size groups compared.