The influence of boating disturbance on the parental care behaviors of smallmouth bass (Micropterus dolomieu)

Anthropogenic noise is a sensory pollutant altering aquatic soundscapes through increases in human-generated noise, such as those from the growing use of recreational boats. Motorboats produce low-frequency noise that overlaps with marine and freshwater fish hearing, yet freshwater species are less studied than their marine counterparts. While anthropogenic noise has been found to influence freshwater fish behavior, alterations to behaviors associated with reproduction, such as parental care, may be more detrimental to a population. To fill this gap, we conducted a manipulative field-based study to examine how anthropogenic noise from motorboats impacted parental care behaviors of smallmouth bass (Micropterus dolomieu). Smallmouth bass were exposed to boat disturbance manipulations with four distinct noise phases: a five-minute pre-boat noise phase (no noise manipulations prior to boat pass), a 30-s boat noise phase (boat driven within 2 m of the nest), post-boat noise 1 (0-5 min) and post-boat noise 2 (5-10 min). Findings show that bass decreased the amount of time swimming on the nest after the noise disturbance (2.5 %) compared to the behavior demonstrated prior to the noise (14 %). These changes persist for at least 10 min after the disturbance. Furthermore, smallmouth bass changed their behavioral repertoire when exposed to boat noise manipulations including aggression, with behavioral changes persisting 10 min after the boat noise had passed. Aggression was not present prior to the disturbance. Parental care behaviors are essential for successful spawning events in various taxa, and interruptions during this critical period can have implications for population dynamics due to reduced offspring survival.