Spatial and Temporal Variability in the Egress of Southern Flounder in the Northern Gulf of Mexico
Abstract
Long-term fisheries independent data indicate that southern flounder (Paralichthys lethostigma) populations in the northwestern Gulf of Mexico have declined in recent years. Although fishing regulations have been implemented to promote the rebuilding of the southern flounder population in Texas, the specific timing and magnitude of spawning runs is poorly understood, limiting the ability of fishery managers to match regulations (e.g., timing of reduced bag limits) with natural migration patterns. Egress patterns of southern flounder were assessed using conventional tags and acoustic telemetry with receivers strategically placed throughout the Galveston Bay Complex (GBC), including the coverage of tidal passes connecting bays to the Gulf of Mexico (GoM).
Vemco V-9 acoustic transmitters were placed inside the peritoneal cavity of adult southern flounder (range: 40-60 cm TL), tagged at several locations within the GBC to ensure that movement behaviors were representative of the GBC population. Southern flounder showed high site fidelity to tagging sites during the summer but made directed movements (> 5 km) out the GBC in the fall and early winter (November-January). Although egress into the GoM was observed for several tagged southern flounder, others were detected in the GBC throughout the suspected spawning season, suggesting that some fraction of the population may overwinter in the bay. This research also demonstrated that southern flounder have the capacity for large-scale movements into adjacent bay systems in Texas, and therefore it is possible that the population in the GBC may rely on production or recruitment from other bay systems along the Texas coast.
Citation
Steffen, Christopher (2019). Spatial and Temporal Variability in the Egress of Southern Flounder in the Northern Gulf of Mexico. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /189195.