Differential Predictors of Adult versus Juvenile Distributions of Two Coastal Pelagic, Surf Zone Fishes along the Northern Gulf of Mexico

As coastal human populations increase and offshore fishery regulations become more stringent in the northern Gulf of Mexico, nearshore fisheries may be subjected to increased exploitation. Spanish Mackerel Scomberomorus maculatus and Florida Pompano Trachinotus carolinus are two nearshore, coastal migratory pelagic species vulnerable to undergoing changes in fishing pressure; however, information is incomplete in regards to understanding their current distributions and movement patterns, both of which are important for effective fishery management. We used a 2-year (2011-2012) gill-net and seine survey to assess surf zone distributions of Spanish Mackerel and Florida Pompano in the northern Gulf of Mexico (Horn Island, Mississippi, to Pensacola, Florida). Unbiased catch-per-unit-effort estimates (by the delta method) were greatest in Alabama and during spring months. Lowest catches occurred during the warm summer months. Overall, subadult-adult Spanish Mackerel presence could be predicted (using a delta-lognormal general linear model) by geographic area, beach habitat, and depth. Florida Pompano presence could be predicted by month and beach habitat. For both species, the abundance could not be predicted by any of the examined variables. Juvenile Florida Pompano presence, contrastingly, could be predicted by month and salinity, and abundance by month and water temperature. Both species had spatio-temporal variability in distribution and catch rates, but beach habitat appeared to be a better predictor for subadults and adults of both species, whereas month and salinity were better predictors for juvenile Florida Pompano catches. Greater catches generally corresponded with proposed migration patterns but also suggest that individuals, at least temporarily, leave the surf zone during the day in the warm summer months. Furthermore, although legal-sized individuals of both species can co-occur in the surf zone in the northern Gulf of Mexico, the increase in Spanish Mackerel presence with depth suggests that Spanish Mackerel fisheries could potentially move further offshore to avoid user conflict with Florida Pompano fisheries.