Hydrodynamic mechanisms driving scallop beach strandings: coupling among wind, waves, and currents in San José Gulf, Patagonia, Argentina

Abstract

Tehuelche scallop (Aequipecten tehuelchus) beach strandings are recurrent events along the northern coast of San José Gulf (Patagonia, Argentina), with major ecological and fishery implications. This study analyzed six historical strandings (1973–2022) using environmental reanalysis datasets, wave modelling and in situ current measurements, aiming to characterize the hydrodynamic mechanisms driving these events. Southerly windstorms can generate waves capable of producing orbital motion in the bottom with intensity higher than 50 cm/s in shallow waters (<5 m), facilitating the dislodgement of scallops. Once dislodged, scallops are transported onshore by Stokes drift with magnitude on the order of 1–5 cm/s and wind-driven currents. Near the coast, scallops are affected by strong longshore currents of about 100 cm/s that promote their accumulation in convergence zones along the northeast coast. This study shows the interaction of wind, currents and wave-driven processes as the main hydrodynamic mechanism of scallop beach strandings, providing insights for understanding the resource's population dynamics and guiding fishery management strategies.