Abundance of fin whales ( Balaenoptera physalus ) in the north‐western Mediterranean Sea, using photo‐identification and microsatellite genotyping

• Published in: Marine Ecology
• Main Authors: Tardy, Céline, Ody, Denis, Gimenez, Olivier, Planes, Serge
• Other Authors: Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), Université Paul-Valéry - Montpellier 3 (UPVM)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud )-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro Montpellier, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université de Montpellier (UM)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: [SDE]Environmental Sciences; Balaenoptera physalus; Fin whale
• Online Access: https://hal.science/hal-04234625; https://doi.org/10.1111/maec.12737

Abstract The Mediterranean fin whale population, Balaenoptera physalus , is resident, with almost no exchanges with the Atlantic population. The entire population was estimated at 1300 or 13,300 individuals by a recent project depending on the platform used. This disparity shows the importance of long‐term monitoring with a unique protocol of survey. Capture‐recapture approaches using dorsal photographs and genetic identity collections over a 10 years period were used to estimate the abundance of the north‐western Mediterranean fin whale. We identified 332 individuals using photographs and 470 using genotypes, with a total of 546 individuals identified between 2008 and 2019, when some whales were double‐marked. The inter‐annual percentage of recapture varied between 15% and 17% respectively for genotypes and photographs methods. Using Cormack‐Jolly‐Seber models, the abundance of fin whales in the north‐western Mediterranean is estimated at 1295 individuals (95% CI: 1116–1474) with a survival probability of 0.945 (95% CI: 0.690–0.993) from genotypes. Abundance estimates from combined collections (photographs and genotypes) and corrected photograph estimates were similar to the genetic ones. Future studies might prioritize the genetic approach which is the least biased and with a narrower confidence interval. The genetic abundance estimates show relative stability over time, when compared to 1990 estimates, and should be included in future conservation actions.