Dear MARMAM community, On behalf of my co-auhtors, I am happy to share the publication of the following paper in Frontiers in Marine Science. "Matching visual and acoustic events to estimate detection probability for small cetaceans in the ACCOBAMS Survey Initiative" Ollier C, Sinn I, Boisseau O, Ridoux V and Virgili A (2023) ABSTRACT Estimating the detection probability of small cetaceans using either visual or acoustic surveys is difficult because they do not surface or vocalise continuously and can be imperceptible to an observer or hydrophone. Animals seen at the surface may have lower vocalisation rates, while submerged individuals may be more vocally active. This study aims to estimate visual, acoustic and combined detection probability by using Mark-Recapture Distance Sampling (MRDS) methodology. We used vessel-based visual sightings and acoustic data (based on click identification) collected simultaneously during the ACCOBAMS Survey Initiative in summer 2018 onboard the R/V Song of the Whale. This study focused on small cetaceans in the Mediterranean Sea, including the most commonlyencountered species, the striped dolphin (Stenella coeruleoalba). We identified duplicate events between visual and acoustic platforms using a decision tree based on time and distance thresholds to estimate g(0) (the detection probability on the trackline) for small cetaceans. A total of 30 duplicate events were identified from 107 and 109 events identified by the visual and acoustic platforms respectively. We tested the models with two key functions. With a hazard-rate key function, the g(0) was estimated at 0.52 (CV=21.0%) for both platforms combined, 0.29 (CV=25.6%) for the visual platform and 0.32 (CV=25.1%) for the acoustic platform. With a half-normal key function, g(0) was estimated at 0.51 (CV = 21.7%) for both platforms combined, 0.29 (CV = 25.6%) for the visual platform and 0.33 (CV = 23.2%) for the acoustic platform. Our results illustrate that passive acoustic monitoring can be used as an independent platform in MRDS to estimate the detection probability. Our estimate of g(0) was well below 1, far from the perfect detection commonly assumed for abundance estimation. Without correction for detection biases, total abundance would be underestimated by a factor of two when using both acoustic and visual data. This highlights the importance of using dual-platform surveys to estimate detection probability in order to improve abundance estimates and conservation efforts. Open Access the full research from here: https://doi.org/10.3389/fmars.2023.1244474 Best regards --- Camille Ollier PhD Student La Rochelle University, France. Centre d'Etude Biologique de Chizé (UMR 7372) Observatoire PELAGIS (UAR 3462) camille.oll...@univ-lr.fr
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