Marine Mammal Detection Summary

The purpose of the Adrift project was to collect baseline data to identify which marine mammal species frequent the Morro Bay, Humboldt, and Oregon Wind Energy Areas, and to describe their seasonal occurrence and distribution within the greater California Current Ecosystem. Different call types are understood to be associated with specific behaviors and therefore provide information related to habitat use. For mysticete (baleen) whales, we focused on blue whales (Balaenoptera musculus), fin whales (B. physalus), Bryde’s whales (B. edeni), sei whales (B. borealis), humpback whales (Megaptera novaeangliae), gray whale (Eschrichtius robustus) and minke whales (B. acutorostrata). For odontocetes (toothed whales), we focused on sperm whales (Physeter macrocephalus), beaked whales (all regional species), dolphins (including Risso’s dolphins, Grampus griseus, and Pacific white-sided dolphins, Lagenorhynchus obliquidens), and narrow band high frequency (NBHF) species (harbor porpoise, Phoceona phocoena, Dall’s porpoise, Phocoenoides dalli, and Kogia spp.). Passive acoustic monitoring relies on sounds produced by animals for detection, and therefore PAM studies cannot identify the absence of animals. Data analysis for fin, sei, and Bryde’s whales was contracted through OSA (Ocean Science Analytics). Specific details on detection methods are provided in our GitHub Adrift Analysis Methods.

Presence of sounds were noted in hourly bins; and detection methods varied by species. Analysis was not conducted on recordings deemed unusable due to excessive self-noise. In addition, an acoustic event of unknown species (possible sei/blue whale) was detected on Adrift-060 off Oregon in 2023; this extended acoustic encounter includes a number of frequency-modulated call types (for more information, see OSA_Appendix_UniqueAcousticEncounters.docx on our Github Repository).