Pelagic Habitat Use by Juvenile Reef Fishes in the Northern Gulf of Mexico

The assemblage composition, abundance, biomass, and vertical distribution of juvenile reef fishes in the offshore pelagic habitat of the northern Gulf of Mexico are described. This study, a component of the NOAA-supported Offshore Nekton Sampling and Analysis Program, is the first to examine juvenile reef fish distributions across the oceanic northern Gulf of Mexico after the Deepwater Horizon oil spill. Results presented here are derived from a 3-month, spring/summer research cruise in 2011 on the M/V Meg Skansi. A 44-station sampling grid covering an area of 420 X 120 nautical miles was sampled with a 10-m2 MOCNESS midwater trawl from the surface to a depth of 1500m, both day and night at each station. A total of 85,475 fish specimens were collected from 373 samples, including 767 reef fish specimens representing 52 species from 29 families. Initial analysis has revealed the presence of juveniles of some species in locations where adults are not known to occur. Juveniles were found almost exclusively in the uppermost 200m of the water column. A greater number of individuals were collected in nighttime trawls. Surprisingly, some individuals were sampled between 1000- 1500m. During the MS7 sampling program, hydrographic profiles of the water column were recorded. This information provides the hydrographic background setting against which the coastal reef fish distributions in the offshore pelagic habitat of the Gulf of Mexico can be characterized. Results of fish distributions as a function of location (relative to the shelf break) and major mesoscale oceanographic features will be presented