Full Description

"During their spawning period (June to mid-July) in the Gironde estuary, meagre Argyrosomus regius produce two distinct sounds: regular long grunts, the most common calls, and sometimes also short grunts. It is suggested that long grunts serve the formation of spawning aggregations and short grunts announce the beginning of courtship behaviour. The meagre’s long grunts include long series of 30–112 closely spaced pulses placed into call units. Each pulse produces multiple and rapidly decaying swimbladder vibrations with a dominant frequency varying between 336 and 444 Hz."

"During this period (May to July), large choral aggregations of male and female meagre form, and their mating calls facilitate fishing in this particular spawning site (Duhamel de Monceau, 1769–1789; Que´ ro, 1989a). Fishermen listen, with their ear to the hull of theirs boats, to the aggregative calls and try to place their gillnets as close as possible to the fish aggregations."

"Meagre spawning sounds were produced during spawning periods in the Gironde estuary in dense choruses in which individual sound emissions were impossible to discriminate [Fig. 2(a)]."

"The most common calls were long grunts with durations of 598–2496 ms (Figs 2 and 3). The rate of calling (12–13 long grunts min1), as well as the call duration varied individually (Table I). Long grunts consisted of trains of 30–112 pulses. The pulse period (i.e. sonic muscle contraction rate) was very regular: mean +- S.D. = 20.1 +- 0.9 ms (n = 77), giving a pulse rate frequency varying between 41 and 52 Hz (mean +- S.D. = 50 +- 2 Hz, n = 77; Fig. 3). Pulses consisted of about three cycles and varied in duration from 7.4 to 14.4 ms (mean +- S.D. = 11 +- 2 ms; n = 77). Their dominant frequency ranged from 336 to 444 Hz (Table I). Most energy occurred in the first cycle, and the amplitude of the second cycle decayed by about half. A third cycle was barely above background. The period of each successive cycle increased suggesting a forced response rather than one dictated by the resonant frequency of the bladder."

"Short grunts consisted of trains of four to six pulses (Fig. 4). Pulses consisted of 1.5 to 2.5 cycles and varied in duration from 4.5 to 11.7 ms (mean +- S.D. = 7 +- 2 ms; n = 33). Similarities were observed in the waveform of short grunts and long grunts. The short grunt durations varied from 69.9 to 99.2 ms and their periods between 594 and 5281 ms (Table I). Although distance to the recorded fish is unknown, the somewhat shorter and weaker pulses suggest that this sound may be weaker than the long grunt. After short grunt emissions, long calls of nearby individuals ceased."

"Nevertheless, the knowledge of the fishermen places the peak of meagre sound emissions late in the afternoon, in accordance with what is known concerning several other sciaenid species (Mok & Gilmore, 1983; Holt, 2003)."

"Nevertheless, it was observed on board the fishing boat that adult males (weighing between 6 and 20 kg) continued having contractions of the sonic muscles (felt by hand) and long grunts were heard for a few minutes after being caught. Females, which were caught less often, were not observed producing sound. In addition, hypertrophy in male sonic muscles, similar to those observed in the male weakfish (Ono & Poss, 1982; Connaughton & Taylor, 1994; Connaughton et al., 1997), indicates that meagre males could be the main contributors to the recorded sound emissions. The observations, however, do not allow sound production by females to be rejected, which could exist as observed by Takemura et al. (1978)."

"The recording of short grunts was rare in the field. Therefore, it is difficult to interpret the potential role of these short calls."

Observation Environment Quotes

"The recording material was taken aboard a Gironde estuary fishing boat, and the recordings were made either during the drifting of the boat pulling the net, with the engine stopped, or during periods when the fisherman was listening for fish aggregations."

Behaviour Description Quotes

"During their spawning period (June to mid-July) in the Gironde estuary, meagre Argyrosomus regius produce two distinct sounds: regular long grunts, the most common calls, and sometimes also short grunts. It is suggested that long grunts serve the formation of spawning aggregations and short grunts announce the beginning of courtship behaviour. The meagre’s long grunts include long series of 30–112 closely spaced pulses placed into call units. Each pulse produces multiple and rapidly decaying swimbladder vibrations with a dominant frequency varying between 336 and 444 Hz."

"Nevertheless, it was observed on board the fishing boat that adult males (weighing between 6 and 20 kg) continued having contractions of the sonic muscles (felt by hand) and long grunts were heard for a few minutes after being caught. Females, which were caught less often, were not observed producing sound."

"Nevertheless, the meagre spawning sounds are different from typical sciaenid sounds because pulses are so close together (pulse period = 20 ms) that they are heard as a unit of pulses (long grunt) rather than a train of individual pulses."

Sound Name Quotes

"During their spawning period (June to mid-July) in the Gironde estuary, meagre Argyrosomus regius produce two distinct sounds: regular long grunts, the most common calls, and sometimes also short grunts. It is suggested that long grunts serve the formation of spawning aggregations and short grunts announce the beginning of courtship behaviour. The meagre’s long grunts include long series of 30–112 closely spaced pulses placed into call units. Each pulse produces multiple and rapidly decaying swimbladder vibrations with a dominant frequency varying between 336 and 444 Hz."

"During this period (May to July), large choral aggregations of male and female meagre form, and their mating calls facilitate fishing in this particular spawning site (Duhamel de Monceau, 1769–1789; Que´ ro, 1989a). Fishermen listen, with their ear to the hull of theirs boats, to the aggregative calls and try to place their gillnets as close as possible to the fish aggregations."

"Meagre spawning sounds were produced during spawning periods in the Gironde estuary in dense choruses in which individual sound emissions were impossible to discriminate [Fig. 2(a)]."

"Because meagre short calls correlated with the cessation of drumming, they were probably emitted by a female meeting a male to involve a courtship with it, or by a male starting a pursuit of a female."

"Nevertheless, the meagre spawning sounds are different from typical sciaenid sounds because pulses are so close together (pulse period = 20 ms) that they are heard as a unit of pulses (long grunt) rather than a train of individual pulses. This characteristic gives a tonal nature to the long grunt sound emissions contrasting with the pulsed sound emitted by the majority of other sciaenid species (Fish & Mowbray, 1970), excepted the two species studied by Takemura et al. (1978): N. albiflora and A. argentatus."