Derville Solène auteur aut IRD Calambokidis J. auteur aut IRD Palacios D. M. auteur aut IRD Tackaberry J. auteur aut IRD Hayslip C. auteur aut IRD Flynn K. auteur aut IRD New L. auteur aut IRD Baker C. S. auteur aut IRD Steel D. auteur aut IRD Martien K. K. auteur aut IRD Moore J. E. auteur aut IRD Lauf M. auteur aut IRD Wickman L. auteur aut IRD Wall A. auteur aut IRD Newell C. auteur aut IRD Torres L. G. auteur aut IRD text journalArticle eng text/pdf reformatted digital access Entanglements in fishing gear are a significant threat to cetaceans worldwide and a concern for large whales in US waters. Yet, entanglement events are infrequently observed, and their lethal and sublethal impacts are likely underestimated. Photographic analysis of wrapping scars on whales shows promise to better assess entanglement. Here, we analyzed scars on 571 individual humpback whales photographed in Oregon, USA, waters (2005-2023). We scored 1533 photos of the tailstock and fluke regions for evidence of prior entanglement. We found that scarring prevalence varied by photo type, with perpendicular/forward tailstock photos showing the highest scarring prevalence (respectively 19.1% and 17.6% most likely caused by entanglements) compared to photos of the fluke underside that tended to miss likely entanglement events (57.4% false negatives). Depending on the scoring approach, 8.2 to 27.3% of sampled whales were likely entangled at least once in their lifetime. We found no significant spatial effect on scarring prevalence and a weak increasing (2016-2020), then decreasing (2020-2023), temporal trend. Males had a significantly higher scarring prevalence than females. Simulations of population trajectory and photographic sampling designs revealed that, even in an unrealistically optimistic scenario of new fishing regulations reducing the number of entanglements to zero, 165 ind. yr-1, for 5 yr, would need to be sampled with good-quality tailstock photos to detect the decrease in scarring prevalence with 80% statistical power. Our findings enable recommendations for monitoring impacts of fishing gear interactions with humpback whales using US West Coast waters. specialized Fisheries bycatch Large whales Photographic data Genetics Scar analysis Simulation Oregon US West Coast ETATS UNIS PACIFIQUE OREGON 040 082 57 253-271 2025 1863-5407 https://www.documentation.ird.fr/hor/fdi:010094397 10.3354/esr01416 1863-5407 [F B010094397] https://www.documentation.ird.fr/hor/fdi:010094397 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2025-09/010094397.pdf IRD - Base Horizon / Pleins textes 2025-09-24 2025-09-24 fdi:010094397 fre