Investigating the seasonal migration of Cobia (Rachycentron canadum) and the influence of temperature on movement ecology
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The pelagic Cobia (Rachycentron canadum) is the target of a popular recreational fishery from the Gulf of Mexico to the mid-Atlantic that shifts seasonally as these fish migrate along the east coast of the United States. Variation in migratory behaviors, when consistent through time, drives the formation of genetic substructure within a population. Movement ecology research works in combination with other stock delineation techniques, like genetic analyses, to indicate such population structure. Intrapopulation variability in spatio-temporal distributions has significant consequences for fishery encounter rates. Temperature is a proposed driver of this seasonal movement in Cobia. In this study, we used passive acoustic telemetry to investigate the migration of Atlantic Cobia. Our results corroborated the timing and spatial distribution of the described north-south Cobia spawning migration in which North Carolina waters serve as a migration corridor and Chesapeake Bay in Virginia is a major spawning site. We characterized seasonal differences in space use — longitudinal variation in path, with Cobia travelling nearshore in the spring and dispersing offshore in the fall — and other intrapopulation variation in migratory behavior (i.e., distinct subsets of Cobia overwintering offshore in North Carolina waters and spending the spawning period in marine habitat south of Chesapeake Bay) that will inform management of the fishery and future interpretation of genetic studies. Following our preliminary analysis, the influence of temperature (i.e., warm, thermally stable continental shelf habitat facilitating offshore overwintering in North Carolina) on the migration of this highly migratory species — and thus on a lucrative fishery — is better understood.