Movements, habitat utilization, and post-release survival of cobia (Rachycentron canadum) that summer in Virginia waters assessed using pop-up satellite archival tags

Background: Cobia (Rachycentron canadum) is a cosmopolitan marine fish that inhabits tropical, sub-tropical, and temperate marine and estuarine waters and supports a major recreational fishery along the U.S. Atlantic and Gulf of Mexico coasts. Recent changes in U.S. cobia management have sparked controversy and highlighted limitations in our understanding of the species' biology. This study utilized pop-up satellite archival tags (PSATs) to assess the movements, habitat utilization, and post-release survival of cobia that summer in Virginia waters. Results: PSATs were deployed on 36 cobia caught in Virginia state waters using standard recreational techniques in August 2016 and August-September 2017. All fish larger than 37-in total length were tagged, and several of these were hooked deeply. No mortalities were inferred for the 20 cobia whose PSATs reported and remained attached for at least 10 days. Premature release of tags was an issue, and only five PSATs remained attached for the full 180-day deployment period. Some fish undertook long seasonal movements, with one individual entering Florida waters well beyond the current stock demarcation boundary. Several fish overwintered in waters offshore of North Carolina near the continental shelf break. Cobia demonstrated a strong affinity for waters ≥ 20 °C, even in the coldest months. They displayed distinct seasonal differences in habitat utilization, spending high proportions of their time near the surface during the summer months and extended periods at depths ≥ 20 m in the winter months. Conclusions: Cobia are hardy fish with low post-release mortality when handled respectfully. Their migratory patterns are clearly temperature driven, and seasonal changes in habitat utilization means varied vulnerability to fishing gears. Further understanding of cobia migratory patterns, particularly in conjunction with spawning activity, is needed to best manage this species.