Full Description

"Single, simultaneous twitches of the bilateral sonic muscles produce a single sound pulse consisting of a two- to threecycle acoustic waveform. Typical disturbance calls at 18 °C consist of trains of 2–15 pulses with a sound pressure level (SPL) of 74 dB re 20 µPa at 10 cm, a peak frequency of 540 Hz, a repetition rate of 20 Hz and a pulse duration of 3.5 ms. The pulse duration suggests an incredibly short twitch time. Sound pressure level (SPL) and pulse duration increase and dominant frequency decreases in larger fish, whereas SPL, repetition rate and dominant frequency increase and pulse duration decreases with increasing temperature. The dominant frequency is inversely related to pulse duration and appears to be determined by the duration of muscle contraction. We suggest that the lower dominant frequency of larger fish is caused by a longer pulse (=longer muscle twitch) and not by the lower resonant frequency of a larger swimbladder."

"Action potential duration (Fig. 1B), measured from the initiation of depolarization to the point where repolarization crossed the zero line, was 2.1±0.2 ms (mean ± S.D., N=20). This was followed by a waveform of opposite polarity that varied in duration from 5.8 to 11.5 ms (mean 8.9±1.8 ms) for a total duration that ranged from 7.9 to 13.6 ms. The time between the initiation of the action potential and the initiation of the sound pulse averaged 2.2±0.4 ms (Fig. 1B). The interval from the time of maximum depolarization of the action potential to the initiation of the sound pulse averaged 1.0±0.4 ms. These values do not take into consideration the speed of sound travelling from the muscle to the microphone 10 cm away, which would reduce the delay by approximately 0.3 ms."

"Disturbance calls evoked by removing fish from the water had a median of three pulses, and ranged from one to more than 20 pulses. A voluntary train of pulses recorded in the field (Connaughton and Taylor, 1994) or during spawning in the laboratory (Connaughton and Taylor, 1996) had a median of six pulses, and a range of 4–10 pulses, but disturbance and unsolicited calls were otherwise similar (Fig. 2). While pulses in a given train were typically of similar SPL, variations in pulse SPL of up to 9 dB were noted within a train, in both evoked and voluntary sounds (see Fig. 1A, top recording). Several trains of drumming were typically produced by the fish during handling. The oscillogram of recorded sound pulses consisted of 2–3 cycles of acoustic energy, with the third cycle often greatly attenuated. In most recordings, the second cycle had the greatest amplitude (Fig. 3, center recordings). A typical disturbance call for a fish of 28–31 cm total length, recorded at 18 °C, included a train of 2–15 pulses with a sound pressure level (SPL) of 74 dB (re 20 µPa at 10 cm), a peak frequency of 540 Hz, a repetition rate of 20.2 Hz and a pulse duration of 3.5 ms."

"Across a range of 11 cm of total length (25–36 cm), SPL increased by 9.7 dB from 65.6 to 75.3 dB, pulse duration increased by 0.6 ms from 3.3 to 3.9 ms and dominant frequency decreased by 91 Hz from 560 to 479 Hz."

"Over the range of temperatures from 12 to 23 °C, the call of 28–31 cm fish ranged in SPL from a mean of 69.6 to 75.5 dB, in repetition rate from 13.4 to 24.3 Hz and in dominant frequency from 494 to 554 Hz. Pulse duration decreased from 3.7 to 3.4 ms."

"Pulse duration ranged from 3.3 to 3.9 ms across a decrease of 81.2 Hz in dominant frequency (from 560.9 to 479.7 Hz) in the size experiment and from 3.21 to 3.95 ms across a decrease of 165 Hz (from 606 to 441 Hz) in the temperature experiment."

"Drumming behavior in weakfish has been correlated with spawning in the field (Connaughton and Taylor, 1994) and observed in courting fish in captivity (Connaughton and Taylor, 1996). The weakfish disturbance calls recorded in this study were similar to the voluntary calls recorded in the field during the spawning season (Fig. 2). Weakfish do not naturally produce the drumming call outside the spawning season (Connaughton and Taylor, 1995b), nor do they produce these sounds if startled in captivity (when chased with a net, M. Connaughton, personal observation). Together, these observations indicate that the acoustic repertoire of the weakfish is surprisingly undifferentiated, and that the courting and disturbance calls may be essentially the same call."

Observation Environment Quotes

"Fish used to determine the effects of total length on acoustic parameters were maintained in a 4500 l circular enclosure at 18 °C. Fish used to examine the effects of temperature on acoustic parameters were maintained in a 1500 l circular enclosure at temperatures that were changed from 18 °C to 23 °C to 12 °C and back to 18 °C during the course of the experiment."

Behaviour Description Quotes

"The purpose of the present study was to describe the disturbance call (a call made voluntarily when the fish is handled out of the water) of the weakfish, including quantitative effects of temperature and fish size on acoustic parameters, to gain insight into sound generation, and to examine the scope of variability likely to be encountered by investigators examining natural spawning populations."

"Simultaneous sound and EMG recordings were made in air from a single adult male weakfish (total length 31 cm) maintained under cold conditions for approximately 8 hours (10 °C) to prolong survival time out of the water. "

"Disturbance calls evoked by removing fish from the water had a median of three pulses, and ranged from one to more than 20 pulses. A voluntary train of pulses recorded in the field (Connaughton and Taylor, 1994) or during spawning in the laboratory (Connaughton and Taylor, 1996) had a median of six pulses, and a range of 4–10 pulses, but disturbance and unsolicited calls were otherwise similar (Fig. 2)."

"Drumming behavior in weakfish has been correlated with spawning in the field (Connaughton and Taylor, 1994) and observed in courting fish in captivity (Connaughton and Taylor, 1996)."

Sound Name Quotes

"Single, simultaneous twitches of the bilateral sonic muscles produce a single sound pulse consisting of a two- to threecycle acoustic waveform. Typical disturbance calls at 18 °C consist of trains of 2–15 pulses with a sound pressure level (SPL) of 74 dB re 20 µPa at 10 cm, a peak frequency of 540 Hz, a repetition rate of 20 Hz and a pulse duration of 3.5 ms. The pulse duration suggests an incredibly short twitch time. Sound pressure level (SPL) and pulse duration increase and dominant frequency decreases in larger fish, whereas SPL, repetition rate and dominant frequency increase and pulse duration decreases with increasing temperature. The dominant frequency is inversely related to pulse duration and appears to be determined by the duration of muscle contraction. We suggest that the lower dominant frequency of larger fish is caused by a longer pulse (=longer muscle twitch) and not by the lower resonant frequency of a larger swimbladder."

"We examined the effects of specimen total length (TL) and temperature on the characteristics of drumming sounds. "

"We recorded drumming bursts or trains, which consist of a series of sound pulses. A pulse consists of 2–3 cycles of acoustic energy."