Acoustic monitoring indicates a correlation between calling and spawning in captive spotted seatrout (Cynoscion nebulosus)

Abstract

BackgroundFish sound production is widespread throughout many families. Territorial displays and courtship are the most common reasons for fish sound production. Yet, there is still some questions on how acoustic signaling and reproduction are correlated in many sound-producing species. In the present study, our aim was to determine if a quantitative relationship exists between calling and egg deposition in captive spotted seatrout (Cynoscion nebulosus). This type of data is essential if passive acoustics is to be used to identify spawning aggregations over large spatial scales and monitor reproductive activity over annual and decadal timeframes.MethodsAcoustic recorders (i.e., DSG-Oceans) were placed in three laboratory tanks to record underwater sound over an entire, simulated reproductive season. We enumerated the number of calls, calculated the received sound pressure level, and counted the number of eggs every morning in each tank.ResultsSpotted seatrout produced three distinct call types characterized as “drums,” “grunts,” and “staccatos.” Spotted seatrout calling increased as the light cycle shifted from 13.5 to 14.5 h of light, and the temperature increased to 27.7 °C. Calling decreased once the temperature fell below 27.7 °C, and the light cycle shifted to 12 h of light. These temperature and light patterns followed the natural reproductive season observed in wild spotted seatrout in the Southeast United States. Spotted seatrout exhibited daily rhythms in calling. Acoustic signaling began once the lights turned off, and calling reached maximum activity approximately 3 h later. Eggs were released only on evenings in which spotted seatrout were calling. In all tanks, spotted seatrout were more likely to spawn when male fish called more frequently. A positive relationship between SPL and the number of eggs collected was found in Tanks 1 and 3.DiscussionOur findings indicate that acoustic metrics can predict spawning potential. These findings are important because plankton tows may not accurately reflect spawning locations since egg capture is likely affected by predator activity and water currents. Instead, passive acoustics could be used to monitor spotted seatrout reproduction. Future studies can use this captive study as a model to record the estuarine soundscape precisely over long time periods to better understand how human-made stressors (e.g., climate change, noise pollution, and chemical pollutants) may affect spawning patterns.

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

“…Positive temperature anomalies increased calling, while negative temperature anomalies decreased sound production. These findings are similar to reports from captive studies with spotted seatrout, weakfish, oyster toadfish, and red drum, where higher temperatures increased the amount of calling and the number of pulses in a call (Fine 1978, Connaughton et al 2000, Maruska & Mensinger 2009, Montie et al 2016, 2017.The lunar phase significantly influenced calling intensity of oyster toadfish and spotted seatrout. We detected pronounced cyclic patterns in the amount of calling and chorus duration for spotted seatrout.…”

“…chilipepper rockfish Sebastes goodie, California halibut Paralichthys californicus) (Asch 2015). As shown in captive experiments for spotted seatrout, red drum, and weakfish, spawning is strongly associated with the production of courtship sounds (Connaughton & Taylor 1996, Montie et al 2016, 2017. Therefore, listening to the estuarine soundscape may provide an easier, more efficient alternative to plankton sampling to track interannual variability in spawning.…”

“…Saucier & Baltz 1993, Mann & Lobel 1995, Luczkovich et al 2008, Walters et al 2009, Mann et al 2010, Montie et al 2016, 2017. Studies have recorded underwater sounds during spawning seasons and have shown that patterns of peak calling coincide with patterns of reproductive senescence (i.e.…”

“…Red drum sound production peaked in the fall. Based on captive studies that illustrated a positive relationship between the amount of calling and spawning success in sciaenids (Connaughton & Taylor 1996, Luczkovich et al 1999, Lowerre-Barbieri et al 2008, Montie et al 2016, 2017, we speculated that chorusing (i.e. calling intensity score = 3) was a reliable indicator of spawning for silver perch, spotted seatrout, and red drum (Table 4).…”

“…Estimates of the dates for the initiation and termination of the reproductive season, its overall duration, and the number of days and hours in which chorusing occurred may be correlated to year class strength. When comparing multiple years of acoustic data, it is possible that years in which more hours of chorusing were detected would result in larger yields of egg biomass (Guest & Lasswell 1978, Mok & Gilmore 1983, Saucier & Baltz 1993, Connaughton & Taylor 1995, 1996, Luczkovich et al 1999, Aalbers & Drawbridge 2008, Montie et al 2016, 2017. Larger seasonal egg yields may result in a stronger year class.…”