Environmental and Structural Drivers of Fish Distributions among Petroleum Platforms across the U.S. Gulf of Mexico

Abstract

Petroleum platforms in the U.S. Gulf of Mexico (GOM) are important habitats for fishes and support regional fisheries. However, drivers of the horizontal (i.e., latitudinal and longitudinal) and vertical (i.e., position in the water column) distribution patterns of fishes associated with these artificial habitats are not fully understood on a GOM-wide scale. To build upon previous studies on a large spatial scale and focus on species-specific drivers, we conducted 114 submersible rotating drop-camera and water quality sonde surveys at 54 platforms throughout the GOM. We then fitted two sets of binomial generalized additive mixed models integrating environmental and structural (i.e., characteristics of platforms) predictors to encounter/nonencounter data for 17 fish species so as to understand their horizontal and vertical distribution patterns throughout the GOM in platform habitat. Significant predictors for horizontal distribution included distance from shore (for Bermuda Chub Kyphosus saltatrix, Greater Amberjack Seriola dumerili, Vermilion Snapper Rhomboplites aurorubens), salinity (Bermuda Chub, Red Snapper Lutjanus campechanus), the number of platforms within 5 km (Blue Runner Caranx crysos, Crevalle Jack Caranx hippos), and dissolved oxygen concentration (Red Snapper). Significant predictors for vertical distribution included temperature (for Atlantic Spadefish Chaetodipterus faber, Bermuda Chub, Blue Runner, Greater Amberjack, Red Snapper), salinity (Greater Amberjack, Red Snapper), dissolved oxygen concentration (Red Snapper), and seafloor depth (Red Snapper). However, the majority of the study species were not influenced by the predictors included in the horizontal (11 of 17 species) and vertical distribution (12 of 17 species) generalized additive mixed models. Thus, many GOM fishes were found to associate with platforms over a relatively wide range of environmental conditions and platform characteristics. This suggests specific environmental conditions and distinct platform characteristics may not be as important as the simple number of available platforms for determining the distributions of many platform-associated fishes in the GOM.