Patterns of Habitat Use by Age-1 Red Drum within an Estuarine Seascape in the Northern Gulf of Mexico

Acoustic telemetry was used to examine patterns of fine-scale habitat use of age-1 red drum Sciaenops ocellatus in the northern Gulf of Mexico.  Red drum were collected in December 2010 from Galveston Bay, Texas, and surgically fitted with Vemco V9 acoustic transmitters (69kHz). A VR2W Positioning System (VPS) array consisting of a grid of eight passive receivers was positioned on a shallow flat in Christmas Bay, Texas, a small secondary bay in the Galveston Bay estuary containing multiple habitat types (e.g. seagrass, oyster reef, mash edge, and sand bar). The VPS estimated fish position by triangulation, using simultaneous detections of a specific tag by multiple receivers.  Red drum were released into the VPS array in December 2010 and data on habitat use within the array was recorded for 30 days. A total of 16,648 tag detections was recorded by receivers within the array during the study period. Fish positions were plotted in a Geographic Information System (GIS) containing detailed benthic habitat maps, and Euclidean Distance-based Analysis (EDA) was used to determine non-random use of specific habitat types (shoal grass, turtle grass, oyster reef, marsh edge, and sand bar) by red drum. Multiple Analysis of Variance (MANOVA) indicated that habitat use (EDA ratios) differed significantly from expected values for random habitat use. Patterns of habitat use within the array were analyzed in relation to physicochemical characteristics to examine the influence of environmental conditions on the behavior of age-1 red drum in this shallow estuary.