Abstract
Passive acoustic recording ( PAR ) systems are non‐invasive and allow researchers to collect data over large spatial and/or temporal scales. As fish sounds are species‐specific and repetitive, PAR can provide a large amount of data about spatio‐temporal variation in fish distribution and behaviors. Ophidion rochei , found in the Mediterranean and Black Seas, is a sand‐dwelling species, meaning that the behavior of this cryptic nocturnal fish cannot be observed in the field. Fortunately, male O. rochei produce long, multiple‐pulsed calls that are easy to identify. The aim of this study was to determine whether or not male calls are linked to reproduction behaviors. If so, PAR would allow a detailed description of the seasonal and daily rhythms in O. rochei reproduction behavior. A hydrophone was deployed from 18 July 2011 to 21 June 2012 and from 7 June 2013 to 2 July 2013 on a sandy area (42°34′48′′ N, 8°43′43′′ E) in front of the STARES O research station ( NW Corsica). Male sounds were obtained only at night from late spring to early fall. The annual sound production period corresponds to the reproductive season of O. rochei . Sound production followed diel cycles: it was sustained for the entire night at the beginning of the sound production season but limited to shorter periods in the evening during the second half of the season. These differences in daily and seasonal sound production tempo can be used in future recordings to make inter‐annual comparisons and estimate the physiological state of the fish.