SPECIES COMPOSITION, ABUNDANCE, AND VERTICAL-DISTRIBUTION OF THE STOMIID (PISCES, STOMIIFORMES) FISH ASSEMBLAGE OF THE GULF-OF-MEXICO

Species composition, abundance, and vertical distribution of the stomi id fish assemblage were investigated in the eastern Gulf of Mexico, a low-latitude, oligotrophic oceanic ecosystem. Seventy-two described sp ecies, representing 18 genera, and one undescribed species were identi fied from 1155 trawl samples. With an additional 10 species reported e lsewhere, the stomiid species number now known equals 83, making the S tomiidae the most diverse fish family in the Gulf of Mexico. The assem blage was dominated by three species, Photostomias guernei, Chauliodus sloani and Stomias affinis. These species, as well as four other comm on species, exhibited an asynchronous diel vertical migration pattern (450-900 m during day; 20-300, 550-900 m at night). The percentage of the populations of the three dominant species migrating daily ranged f rom 50-70%. Two other patterns occurred in less abundant species: sync hronous migration (400-700 m during the day, 0-200 m at night); and, p ossible migration from the bathypelagial (> 1000 m during day; 50-300 m at night). Minimum abundance and biomass estimates for the entire as semblage were 1.86 x 10(5) individuals and 35.3 kg DW . km(-2) in the upper 1000 m. Stomiids comprised approximately 10% of the micronekton standing stock in the eastern Gulf. Extrapolating eastern Gulf data to the world warm-water mesopelagial, abundance results suggest that sto miids are the dominant mesopelagic upper-trophic level predatory fishe s, and as such may serve as key trophic mediators in the transfer of e nergy in these ecosystems.