Revisiting taxonomy of cephalopod prey of sperm whales caught commercially in subtropical and Southern Ocean waters

• Published in: Deep Sea Research Part I: Oceanographic Research Papers
• Main Author: Cherel, Yves
• Other Authors: Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: Antarctica; Cetacean; Histioteuthidae; Odontocete; Squid; Trophic relationships; [SDE]Environmental Sciences; Antarctic; Macleod; Southern Ocean; The Antarctic; Antarc*; Mesonychoteuthis hamiltoni; Sperm whale; toothed whale
• Online Access: https://hal.archives-ouvertes.fr/hal-03179766; https://doi.org/10.1016/j.dsr.2021.103490

International audience The sperm whale is the largest toothed whale that feeds almost exclusively on oceanic cephalopods. Since it wasactively hunted commercially, considerably more is known about its food than for many other large marine apexpredators. However, the use of those unique dietary information is today hampered by out-of-date cephalopodtaxonomy. Here, the names of cephalopod prey of sperm whales were revisited by reviewing taxonomic investigationsand tracking over time the names of sclerotized beaks that accumulate in predators’ stomachs. Thestudy focused on the seminal investigations by Clarke (1980) and Clarke and MacLeod (1982), which form thebasis of our knowledge on the feeding habits of sperm whales in the Southern Hemisphere. Forty-five differentbeaks were identified, of which the labelling of 24% taxa is valid today, 7% are still undetermined, and the nameof the 69% remaining beaks had to be changed due to improvement in both taxonomy (31%) and beak identification(27%), and to initial misidentifications (11%). Few taxonomic changes occurred at the family level, butchanges at the species level are substantial and reveal the dietary importance of poorly known squid species (e.g.Galiteuthis suhmi, Histioteuthis macrohista). Within the southern subtropics, sperm whales feed primarily on fivehistioteuthids, with Histioteuthis atlantica ranking first numerically, and on octopoteuthids, cranchiids andonychoteuthids. In contrast, whales caught in the Antarctic prey mainly upon three species of Southern Oceanendemics, the cranchiid Mesonychoteuthis hamiltoni, and the onychoteuthids Filippovia knipovitchi and Moroteuthopsislongimana. In conclusion, revisiting taxonomy allowed a better understanding of the deep-sea ecosystemby improving our knowledge on oceanic cephalopods and on the feeding habits of sperm whales, a cephalopodpredator that has a key trophic role in the oceans.