A Comparison of Fish Community Structure at Mesophotic Artificial Reefs and Natural Banks in the Western Gulf of Mexico

Abstract

Oil and gas platforms along the northwestern Gulf of Mexico (GOM) shelf have served as artificial reefs since oil and gas exploration intensified in the 1950s. As these structures are decommissioned, they must be removed; however, some are converted to permanent artificial reefs. Despite the potential effects these artificial habitats may have on marine fisheries, investigations that assess the fish communities inhabiting these structures relative to natural habitats are rare. During fall 2012, we used remotely operated vehicle surveys to compare fish communities between artificial reefs (i.e., reefed platforms; n = 5) and adjacent natural banks (n = 5) in the western GOM. Our surveys successfully documented 79 species representing 28 families. Multivariate analyses suggested that fish communities at artificial reefs were distinct from those at natural banks. Post hoc analyses indicated that the differences were driven by high abundances of transient, midwater pelagics and other gregarious species at artificial reefs. Many fisheries species, like the Red Snapper Lutjanus campechanus, were found in both habitat types, with density at artificial reefs estimated to be nearly eight times greater than at natural banks. Despite lower densities at natural banks, the disproportionately large areas of these habitats resulted in relatively high total abundance estimates—approximately 5% of the 2012 GOM Red Snapper annual catch limit (3.67 million kg [8.08 million lb])—a finding that has significant implications for Red Snapper and artificial reef management in the GOM. Our study suggests that although fish community structure may differ between these two habitats, artificial reefs serve as important habitat for species like Red Snapper by potentially diverting fishing pressure from natural habitats; however, future studies that address species-specific life history traits will be needed to better understand the function and performance of artificial reefs in supporting fisheries productivity.

Received May 4, 2016; accepted December 29, 2016

ACKNOWLEDGMENTS

We are grateful to the Schmidt Ocean Institute for ship time aboard the R/V Falkor and for making the Global Explorer ROV available for this research. Additionally, we thank Thomas Shirley and Wes Tunnell for leading the Coralgal Banks of South Texas cruise and for sharing data and ROV video from the natural banks for our analysis. While onboard the R/V Falkor, our goals could not have been accomplished without the help of the captain, crew, ROV pilots, and scientists. We extend thanks to the staff, students, and interns of the Center for Sportfish Science and Conservation at the Harte Research Institute for Gulf of Mexico Studies for their support of this work. We are especially grateful to Allison Lund and Tara Topping for their help with video processing.