Distribution and Age Composition of Red Snapper across the Inner Continental Shelf of the North-Central Gulf of Mexico

The Red Snapper Lutjanus campechanus is an economically and ecologically important species in the northern Gulf of Mexico, where it often dominates the reef fish community in shallow to mid water depths along the continental shelf. The affinity of Red Snapper for artificial and natural reefs is well established; however, this affinity appears to vary with age. We used a multigear survey that targeted all age-classes of Red Snapper to determine the distribution by age-class on artificial reefs, natural reefs, and unconsolidated mud-sand bottom across the shallow-water (<100 m) portion of the north-central Gulf of Mexico continental shelf. Bottom trawl, remotely operated vehicle (video), vertical longline, and bottom longline surveys were conducted in randomly selected 2-kmx2-km grids that were previously surveyed with side-scan sonar to yield a synoptic understanding of habitat use by age-class. Zero- and 1-year-old Red Snapper (collected from trawls) were found primarily in shallow water (similar to 20-40m deep) on unconsolidated muddy bottom in the northwestern portion of the survey area. Vertical longline catch per unit effort was highest at artificial reef sites, followed by natural reef sites and lastly sites with unstructured bottom. The vertical longline surveys collected 2-8-year-old Red Snapper near artificial and natural reefs, yet the mean age and size of these fish did not differ between the two habitats. Older Red Snapper (5-42years old) were collected on bottom longlines, away from reef structures on unstructured bottom throughout all depth strata. Our results demonstrate ontogenetic changes in habitat use for Red Snapper (from unstructured bottom areas to artificial or natural reefs and back to unstructured bottom areas), but unlike the results from previous studies they do not show a strong trend toward increases in the prevalence of older Red Snapper with increasing depth.