Sound production by red hind Epinephelus guttatus in spatially segregated spawning aggregations

Abstract

Many fishes, including groupers, produce sounds associated with mating behavior; recording and analyzing the occurrence of these sounds can provide long time-series records of grouper use of spawning habitat. Red hind Epinephelus guttatus sound production was recorded on spawning aggregation sites off the west coast of Puerto Rico and at Mona Island, Puerto Rico. Audiovideo recordings were used to identify a species-specific sound produced by male red hind, most commonly during territorial patrols, and also during interactions with females. This sound is low in frequency (50 to 400 Hz) and consists of a series of pulses repeated at a variable rate. Long-term acoustic recorders were placed off the west coast of Puerto Rico at Abrir La Sierra and at Mona Island to record the timing of red hind sound production from January through March. Red hind sounds were detected at all times of the day, with peaks in sound production just before dusk. Monthly peaks in sound production were evident in each time series, but the monthly peak in sound production at Abrir La Sierra was 6 d later than the peak at Mona Island, suggesting that the timing of spawning of these 2 aggregations, while on a lunar schedule, was not broadly synchronized during this time period. This research lays the groundwork for both long-term monitoring and mapping of red hind spawning sites that will be useful for managing spawning aggregations, especially in remote areas.KEY WORDS: Red hind · Spawning aggregation · Sound production · Mona Island · Puerto Rico Resale or republication not permitted without written consent of the publisherRed hind were recorded by Tavolga (1968) and Fish & Mowbray (1970) as part of a survey of sounds produced by fishes. In their studies, red hind were found to produce low-frequency pulsed sounds with most of the energy below 200 Hz. These sounds were recorded from captive specimens, and were likely defensive sounds associated with being handled. It is possible that the sounds recorded in captivity were not representative of the sounds that might be produced by aggregating red hind, as has been observed for many sciaenids. The goals of the present study were to record and characterize sounds from wild red hind on known spawning aggregation sites and to document long-term patterns of sound production from daily to monthly time scales at 2 sites separated by deep water in Puerto Rico during the red hind spawning season. MATERIALS AND METHODS Underwater video recordings.Underwater audiovideo recordings of red hind behavior were conducted by SCUBA divers at Mona Island, Puerto Rico, using Sony PC-110 and SR80 video cameras. Each camera was housed in an Ocean Images underwater video housing and connected to an HTI 96-min hydrophone (sensitivity 2 Hz to 37 kHz; -164 ± 1 dBV µPa -1 ). Recordings were made from January to March 2007 during dives from 16:00 h through dusk. The video recordings were used to record red hind behavior and associated sound production. The audio portion of the recordings was only used for des...

Sound production as an indicator of red hind density at a spawning aggregation

“…Daily sound levels show trends similar to the density build-up and post-spawning departure described by Nemeth et al (2007), with maximum levels around sunset (Mann et al 2010) when red hind have been observed spawning (Colin et al 1987). While passive acoustic methods have been used to describe patterns of sound production at red hind spawning aggregations, the relationship between changes in red hind sound production and density has not been established.…”

“…Red hind produce a low frequency mixed tonalpulse species-specific vocalization associated with courtship and territorial behaviors at spawning aggregations , Mann et al 2010. Daily sound levels show trends similar to the density build-up and post-spawning departure described by Nemeth et al (2007), with maximum levels around sunset (Mann et al 2010) when red hind have been observed spawning (Colin et al 1987).…”

“…Red hind distributions at aggregation sites are relatively fixed, with males protecting a given territory and harem (Shapiro et al 1993a); therefore, surveying the area repeatedly allowed for the documentation of daily changes in density while minimizing variance due to clustering effects. UVC surveys began at 16:00 h Atlantic Standard Time (AST; UTC − 4) when light levels were favorable and red hind territorial, reproductive, and acoustic behaviors were known to be increasing from midday levels (Mann et al 2010, T. J. Rowell pers. obs.…”

“…Following Mann et al (2010), re ceived sound pressure levels in the 100 to 200 Hz frequency band (band levels) were used as a second measurement of red hind sound production; the majority of red hind acoustic energy is within the 100 to 200 Hz band. Band levels were calculated in a custom MATLAB (The Mathworks) software called DSGLab.…”

“…Sound production in a number of species is known to be associated with courtship, territoriality, or reproduction, warranting the use of passive acoustics to locate spawning aggregations (Luczkovich et al 1999, 2008b, Walters et al 2009, Rowell et al 2011) and determine temporal spawning behavior and habitat use by different species , 2010, Nelson et al 2011, Schärer et al 2012.…”