Benthic Habitats and the Effects of Fishing

Delineating Juvenile Red Snapper Habitat on the Northern Gulf of Mexico Continental Shelf

William F. Patterson, Charles A. Wilson, Samuel J. Bentley, James H. Cowan, Tyrrell Henwood, Yvonne C. Allen, and Triniti A. Dufrene

doi: https://doi.org/10.47886/9781888569605.ch46

Abstract. A database of resource survey trawl samples was analyzed to determine if patterns in spatial variability of estimated density of juvenile red snapper Lutjanus campechanus in an approximately 15 × 10³-km² area in the north–central Gulf of Mexico were consistent among years from 1991 through 2000. Areas that consistently produced high (n = 1), median (n = 2), or low (n = 1) estimated juvenile red snapper density during this time series then were mapped with digital side-scan sonar, and differences in acoustic reflectance of the seabed were groundtruthed with sediment analyses of boxcore samples. Spatial variability in juvenile density estimated from trawl samples (n = 80) in summer and fall 2001 were similar to historic patterns. Juvenile density was significantly higher in areas with shell rubble or sponge habitat, thus indicating juveniles require habitat with small-scale (cm to m) complexity. Results of this study indicate our mapping techniques were effective in delineating juvenile red snapper habitat, but future studies also should examine diet, growth, and mortality of juveniles to distinguish suitable versus essential habitats.