Impacts of vessel noise on Red Drum (Sciaenops ocellatus) spawning choruses in Saint Andrew Bay, Florida, U.S.A.

Noise pollution is an increasing threat to soniferous fishes like Red Drum ( Sciaenops ocellatus ), an estuarine, recreational fishery species that vocalizes during spawning. We hypothesized that Red Drum increase, decrease, or do not alter vocalizations in relation to vessel noise exposure. We conducted passive acoustic monitoring in 2021 and 2022 at an estuarine inlet and used Generalized Least Squares models (GLS) to assess vessel noise amplitude over time (sound exposure level, SEL) and other abiotic parameters on Red Drum spawning chorus SELs. GLS models of daily crepuscular choruses indicated a > 5% reduction in proportion to crepuscular vessel noise (dB) in 2021 but not 2022. GLS models testing the influence of abiotic variables and prior vessel noise, also predicted reduced chorus SELs proportional to prior noise SEL: ca. 5% and 3% of vessel SEL in 2021 and 2022, respectively. In some instances, crepuscular chorus SELs exceeded SELs of periods when vessel noise was present. Acute examples were observed in which chorus SELs exceeded SELs of vessel noise periods that occurred immediately before or after. Together, results indicate fish reduce chorus amplitudes during vessel noise, as combined amplitudes (vessel + fish) were lower than fish choruses alone. In peak spawning season (September and October) vessel noise was frequent, detected in > 31% of daily crepuscular recordings on average for both years and up to 100% of recordings on some dates. Observations of disrupted spawning choruses and high vessel noise prevalence suggest spawning behavior may be impacted where vessel noise is abundant.