A Strategic Acoustic Telemetry Infrastructure for Marine Biodiversity in the Strait of Gibraltar and Gulf of Cádiz: STRAITS ^†

Abstract

Introduction: The Strait of Gibraltar, a narrow gateway between the Atlantic Ocean and the Mediterranean Sea, concentrates intense biotic exchange and functions as a global “ecological gate” for marine species. Despite its ecological relevance, sustained acoustic telemetry monitoring has long been hindered by oceanographic complexity, strong currents, intense maritime traffic, and geopolitical constraints. As its Atlantic approach, the Gulf of Cádiz is a highly productive area supporting diverse habitats, key spawning and nursery grounds, and major migration pathways, while underpinning important commercial fisheries. Objective: to deploy a system to enable continuous monitoring of animal movements across this key biogeographic boundary. Methodology: The EU-funded STRAITS project, a multidisciplinary consortium integrating physical oceanography and marine biotelemetry, has deployed an acoustic telemetry curtain across the Strait of Gibraltar, complemented by a coastal acoustic receiver array in the Gulf of Cádiz. Results: Over the past two years, a consistent pattern of frequent acoustic detections has demonstrated the system’s potential. Data reveal spatio-temporal migration patterns of commercially important species such as Atlantic bluefin tuna (Thunnus thynnus) and meagre (Argyrosomus regius), alongside conservation-relevant species like ocean sunfish (Mola mola). Conclusions: These results highlight the Strait of Gibraltar as a biodiversity hotspot and a strategic location for quantifying connectivity, migration timing, and species fluxes, supporting ecosystem-based management and blue policy frameworks.