Multi-Scale Examination of Estuarine Habitat Use and Migration of Southern Flounder (Paralichthyes lethostigma) with Implications for Novel Fisheries Management Approaches

In the last two decades, much effort has been devoted to the incorporation of spatial and temporal approaches in fisheries management. However, quantifying habitat use is arduous for species that exhibit complex life histories.  Addressing these questions require a multi-scale approach. Southern flounder habitat use and migration were studied using acoustic telemetry within a North Carolina estuary. Fine-scale focal follows were conducted for 36 hours to obtain estimates of daily activity space. On a weekly time scale, active tracking of acoustically tagged flounder was combined with sampling of habitat attributes (prey communities and sediment characteristics) within a larger tributary. At the estuary scale, a passive acoustic array was used to quantify migration timing and identify pathways.  During estuarine residency, southern flounder demonstrated small daily activity spaces (7,000m²) with limited movement. Weekly active tracking revealed flounder to mostly congregate in near-shore mid-tributary habitats associated with dense prey fish aggregations with high species richness. Migration followed two main pathways and occurred primarily within a 3-4 week period, with only modest variation among years.  Once migration behavior was initiated, most southern flounder exited the estuary within ten days, and behavior was linked to body size and environmental features associated with passing cold fronts.