Seasonal movements and habitat use of Cobia (Rachycentron canadum) in the Gulf of Mexico

Background Cobia ( Rachycentron canadum ) is a coastal migratory pelagic species that supports a popular recreational fishery along the U.S. Atlantic coast and throughout the Gulf of Mexico (Gulf). Limited knowledge of seasonal movements, stock boundaries, and the subsequent distribution of fishing mortality is a key source of management uncertainty for the Gulf migratory stock. Therefore, the goal of this study was to estimate the seasonal movement patterns and habitat use of Gulf cobia using conventional and satellite tagging. Results Between June 2020 and October 2024, 125 cobia ranging from 432–1302 mm FL were conventionally tagged off the coast of Texas, USA. Of these, 34 were tagged with pop-up archival transmitting (PAT) tags. Excluding six nonreporting tags and four PATs with deployment durations < 10 days, PAT tags released between mid-August and mid-April with deployment durations ranging from 20–180 days (mean = 73 d; SD = 43 d). Observed dispersal from the tagging region suggested cobia moved south-southwest (n = 14; mean = 173.4 km; range = 8.6–719.6 km) or east (offshore; n = 3; mean = 46.9 km; range = 35.8–56.2 km) between September and April. While movements of most individuals were restricted to the tagging region, three PAT tags reported pop-up locations off Mexico. Geolocated maximum likelihood tracks revealed complex movements, with total distances traveled ranging from 697.5–5256.7 km. Estimates of post-release mortality were 3.6% and 26.5%, depending on the treatment of tag attachment failure and non-reporting tags. Cobia displayed strong preferences for surface waters in summer and progressively reduced their time near the surface into winter. Diel- and reverse diel vertical migration behaviors were also observed. Seasonal fidelity to the tagging region was observed, and no cobia were detected north of Galveston, TX. Conclusions This study advances our knowledge of cobia seasonal movement patterns and habitat use in the western Gulf and suggests the South Texas Shelf serves as suitable overwintering habitat for Gulf cobia. Evidence of migratory contingents warrants expansion of cooperative tagging and genetic sampling to better understand stock dynamics and advance effective management strategies in the Gulf.