Abstract
The species identification of whales, dolphins and porpoises at sea remains challenging, particularly for cryptic species like beaked whales (Family: Ziphiidae). Here we use environmental (e)DNA for identification of Sato’s beaked whale, Berardius minimus , at sea. This species was first described in 2019 and, to date, all but one genetic sample has been collected from beachcast carcasses. Sato’s beaked whales are difficult to distinguish at sea from the larger Baird’s beaked whales ( Berardius bairdii ), highlighting the need for reliable methods to identify this species in the field. Using high-throughput metabarcoding of the mtDNA control region, we confirmed visual identification of Sato’s beaked whales in six of the eight eDNA samples collected in the Nemuro Strait. One of the samples also provided a haplotype consistent with a killer whale. From the samples of Sato’s beaked whales, we recovered three of the five previously described haplotypes and resolved two novel variants. These haplotypes have the potential to further describe diversity and population structure in this elusive whale. Our results demonstrate the potential of eDNA metabarcoding as a non-invasive tool for detecting and assessing the genetic diversity of Sato’s beaked whales and other deep-diving cetaceans.