Migratory group discrimination between eastern Gulf of Mexico and Atlantic king mackerel (Scomberomorus cavalla) using otolith shape analysis

King mackerel, Scomberomorus cavalla, are recreationally and commercially important scombrids that migrate from eastern Gulf of Mexico and southeastern Atlantic waters into an area in south Florida known as the mixing zone during winter. Fisheries management allocates all winter landings in the mixing zone during winter to the Gulf migratory group, which does not reflect real conditions. I used otolith shape analysis to develop migratory group-specific tags during summer when groups were separate. Otolith area, perimeter, roundness, circularity, rectangularity, and the first twenty Fourier harmonics were used to compare otolith shape between the two migratory groups. Migratory group classification accuracies using these variables ranged from 65-75%. Winter landings across three zones in south Florida were estimated using a maximum likelihood estimation procedure parameterized with summer shape variables. Estimates indicated higher Atlantic migratory-group contributions in east Florida and lower contributions in west Florida.