Long-term acoustic monitoring of fish calling provides baseline estimates of reproductive time-lines in the May River estuary, southeastern USA

In this study, our goal was to perform acoustic monitoring of the May River, South Carolina (USA), for a 9 mo period and estimate reproductive timelines for a community of soniferous fishes. Acoustic recorders were deployed to collect sound samples for 2 min, every 20 min at 4 stations from the source to the mouth from February to November 2013. We detected the acoustic presence of 6 fish species: Atlantic croaker Micropogonias undulatus, black drum Pogonias cromis, silver perch Bairdiella chrysoura, oyster toadfish Opsanus tau, spotted sea trout Cynoscion nebulosus, and red drum Sciaenops ocellatus. Acoustic detection rates and diversity of soniferous fish were higher near the mouth and de creased towards the source, suggesting a selection of deeper water and/or more stable water quality conditions for spawning. We estimated the start and end dates of the spawning season and calculated the total hours of chorusing for silver perch, oyster toadfish, spotted seatrout, and red drum. Each species followed a specific seasonal and daily pattern of calling, and we observed synchrony of these calling patterns among stations. For silver perch, oyster toadfish, black drum, and spotted seatrout, a negative tem perature anomaly correlated with decreased calling intensity, while a positive anomaly increased sound production. For oyster toadfish and spotted seatrout, the lunar phase significantly influenced calling. These data serve as a foundation for future studies that are investigating how climate variability may affect seasonal spawning timelines and year class strength of fish populations using passive acoustic monitoring.