RT info:eu-repo/semantics/article T1 Comparison of visual and passive acoustic estimates of beaked whale density off El Hierro, Canary Islands A1 Alcázar Treviño, Jesús A1 Arranz, Patricia A1 Miranda, D. A1 Gkikopoulou, K. C. A1 Cardona, A. A1 Aguilar de Soto, Natacha A1 Marques, T. A. A2 Ingeniería Industrial A2 BIOECOMACDepartamento de Biologia Animal, Edafologia y Geologia. Universidad de La Laguna. Avenida Astrofisico F. Sanchez, s/n. 38206 San Cristobal de La Laguna, Tenerife, Spain AB Passive acoustic monitoring (PAM) offers considerable potential for density estimation of cryptic cetaceans, such asbeaked whales. However, comparative studies on the accuracy of PAM density estimates from these species arelacking. Concurrent, low-cost drifting PAM, with SoundTraps suspended at 200 m depth, and land-based sightings,were conducted off the Canary Islands. Beaked whale density was estimated using a cue-count method, with clickproduction rate and the probability of click detection derived from digital acoustic recording tags (DTags), and distance sampling techniques, adapted to fixed-point visual surveys. Of 32 870 detections obtained throughout 206 h ofPAM recordings, 68% were classified as “certain” beaked whale clicks. Acoustic detection probability was 0.15[coefficient variation (CV) 0.24] and click production rate was 0.46 clicks s1 (CV 0.05). PAM density estimateswere in the range of 21.5 or 48.6 whales per 1000 km2 [CV 0.50 or 0.44, 95% confidence interval (CI) 20.7–22.4 or47–50.9), depending on whether “uncertain” clicks were considered. Density estimates from concurrent sightingsresulted in 33.7 whales per 1000 km2 (CV 0.77, 95% CI 8.9–50.5). Cue-count PAM methods under application provide reliable estimates of beaked whale density, over relatively long time periods and in realistic scenarios, as thesematch the concurrent density estimates obtained from visual observations YR 2023 FD 2023 LK http://riull.ull.es/xmlui/handle/915/34716 UL http://riull.ull.es/xmlui/handle/915/34716 LA en DS Repositorio institucional de la Universidad de La Laguna RD 27-dic-2024