Fish chorusing patterns and their environmental drivers in California National Marine Sanctuaries

Marine soundscapes are dominated by fish choruses, when many fish vocalize concurrently, often for mating purposes. Passive acoustic monitoring (PAM) allows us to analyze spatiotemporal patterns of fish chorusing, identifying breeding grounds, species distributions, and mating seasons. By integrating PAM with environmental data (temperature, salinity, etc.), we can assess the environmental drivers of fish chorusing. Through the Sanctuary Soundscape Monitoring project, we collected PAM data across nine sites in Monterey Bay (MBNMS), Chumash Heritage (CHNMS), and Channel Islands National Marine Sanctuaries (CINMS), each recording for ∼2 years for a cumulative 17.9 years. We identified: (1) WHO: five fish choruses, including plainfin midshipman, bocaccio rockfish, white seabass, and two unidentified species; (2) WHERE: spatial variation in chorus types and occurrence; (3) WHEN: predominantly nocturnal, seasonal chorusing aligned with reproductive cycles; and (4) DRIVERS: environmental variables associated with different water masses drive chorusing presence, and fish tended to chorus more during marine heatwaves. Through non-invasively listening to fish, we gain critical insights into their reproductive behavior and environmental drivers, to better inform effective management and conservation, particularly under changing environmental conditions.