Aspects of the trophic ecology of the mesopelagic fish Lampanyctus alatus (family Myctophidae) in the eastern Gulf of Mexico

AbstractLampanyctus alatus is an abundant myctophid in subtropical waters of the eastern Gulf of Mexico. The population has been estimated at 85–140 × 103 fish per km2 of sea surface, with most of the population biomass (>60%) in individuals larger than 35 mm. This species concentrates in the 80175 m zone at night and at 550–750 m during the day. The diet is essentially crustacean (>98%), with over 60 prey species having been identified. Seventy-three percent of the number and 44% of the biomass of the diet are copepods. Euphausiids rank first in biomass and are particularly important in the diet of larger fishes. Lampanyctus alatus is selective for prey >1 mm and for the copepod genus Pleuromamma.A diel feeding cycle is apparent, stomachs being fullest in the period 0100–0500 h. Daily ration is estimated at 2–4% of body weight and decreases proportionately with increasing fish size. It is estimated that one-fifth of respiration and less than one-tenth of the daily ration is utilized in diel vertical migr...