Estimating the impact of ship strikes on the Mediterranean fin whale subpopulation

• Published in: Ocean & Coastal Management
• Main Authors: Sèbe, Maxime, David, Léa, Dhermain, Frank, Gourguet, Sophie, Madon, Bénédicte, Ody, Denis, Panigada, Simone, Peltier, Hélène, Pendleton, Linwood
• Other Authors: Aménagement des Usages des Ressources et des Espaces marins et littoraux - Centre de droit et d'économie de la mer (AMURE), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Universidad de Sevilla = University of Seville
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: [SDV]Life Sciences [q-bio]; Balaenoptera physalus; Fin whale
• Online Access: https://hal.science/hal-04204004; https://doi.org/10.1016/j.ocecoaman.2023.106485

The Mediterranean fin whale (Balaenoptera physalus) subpopulation is under threat from collisions with ships. Given the international dimension of the issue, the French, Italian, Monegasque and Spanish governments have proposed a Particularly Sensitive Sea Area (PSSA), i.e., a management zone of the International Maritime Organization (IMO), in which mandatory and voluntary protective measures can be implemented. Defining the risk and its impact at the subpopulation level is required to improve the chances of an IMO acceptance for such a proposal. While previous research partially succeeded in defining the collision risk, its impact on the subpopulation has not been thoroughly evaluated, especially at the spatial scale of the envisioned PSSA. Our study uses the carcass recovery approach to estimate the number of deadly collisions within the proposed PSSA. We then assess the probability that this number exceeds three management rules: Potential Biological Removal (PBR), Alert Reference Point (ARP) and Critical Reference Point (CRP). These management rules describe thresholds beyond which (a) the incidental mortality may prevent the recovery of the population within 100 years (PBR), (b) there is a cause for concern about incidental mortality (ARP), and (c) there is a critical need to lower the incidental mortality (CRP). We conclude that mortality from collisions alone is in excess of PBR. Taking into account confirmed and suspected collisions in strandings in calculations, the collision mortality exceeds ARP; this threshold being considered unacceptable by some international organisations. Additionally, there is almost a 35% chance that the mortality due to ship strikes exceeds the CRP, likely resulting in a population decline. The probability of anthropogenic mortality exceeding CRP is 60% if we include the fishery-related mortality in stranding (i.e., taking into account the total incidental mortality from bycatch and ship strikes). The PSSA proposal could use our approach to estimate the impact of collisions ...