Understanding the movements of highly mobile marine species is essential for identifying critical habitats and developing effective conservation measures. Although occasional movements of fin whales ( Balaenoptera physalus ) between the Mediterranean Sea and the North Atlantic Ocean have been reported, the extent to which these movements represent a recurrent component of Mediterranean fin whale ecology remains unclear. Here, we present satellite telemetry tracks from seven fin whales (2022–2025) with five years of supporting evidence from systematic land-based observations (2021–2025) in the western Ibiza Channel to investigate movement patterns, behavior, and habitat use beyond the North-Western Mediterranean Sea. All tracked whales left the Mediterranean Sea passing through the Strait of Gibraltar and subsequently moved northward along the Atlantic coast of the Iberian Peninsula, providing direct evidence of cross-basin movements from the Mediterranean to the North Atlantic. Behavioral analyses using two independent movement-modeling approaches identified a common pattern of directed transit followed by area-restricted search (ARS) behavior—commonly associated with foraging—in several Atlantic areas, including waters off the Iberian Peninsula and the Bay of Biscay. The occurrence of prolonged ARS behavior in these areas is consistent with the use of Atlantic feeding habitats. The similarity of movement trajectories across individuals, years, tagging locations, and data streams indicates that seasonal use of Atlantic waters may represent a regular component of the movement ecology of at least some fin whales in the Mediterranean Sea. Given that these movements span multiple jurisdictions and areas of intense maritime activity, conservation measures should consider both important feeding habitats and the migratory routes that connect them.

The development of automatic detection algorithms for fish vocalizations is essential for advancing passive acoustic monitoring and improving our understanding of marine soundscapes. We present an acoustic-feature-based detection framework that combines acoustic entropy and envelope modulation analysis to identify repetitive fish vocalizations in complex coastal environments. The framework was applied to passive acoustic recordings collected in the Cabo de San Antonio Marine Reserve (Spain), an area characterized by dynamic soundscapes and intense vessel traffic. Detection operates through two complementary configurations: an entropy-based mode that identifies temporally coherent low-entropy events, and a combined entropy–envelope modulation mode that validates detections using the relationship between the pulse repetition frequency (f₀) and its second-order modulation component (2·f₀). The combined configuration substantially reduced false-positive detections while simultaneously increasing true-positive detections and reducing false negatives. Event-level evaluation yielded a precision of 0.71, recall of 0.96, and F1-score of 0.82, compared with 0.52, 0.91, and 0.66, respectively, for the entropy-only configuration. Detected signals showed a marked nocturnal pattern with activity peaks around sunset. Their pulse period, peak frequency, and nocturnal occurrence were consistent with published descriptions of Sciaena umbra vocalizations, suggesting this species as a potential biological source while acknowledging that species-level attribution cannot be established from passive acoustic data alone. Overall, the proposed framework provides an interpretable feature-based approach for detecting structured fish vocalizations under the acoustically challenging conditions represented in this dataset.