Full Description

"A mismatch between sound production and hearing in the oyster toadfish, Opsanus tau L., suggests the hypothesis that toadfish communicate over short distances."

"Unlike the case in most animals, a mismatch between sound production and hearing in the oyster toadfish, Opsanus tau, suggests that toadfish communicate over short distances."

"By 200Hz, a typical fundamental frequency of the courtship boatwhistle call (Fine, l978), its threshold has declined over 20dB. An intensely suprathreshold call from a nearby fish is necessary to facilitate a calling male (Fish and Offuiitt, 1972)."'Toadfish may be unable to localize far-field sounds. Since males often call in dense choruses, increased sensitivity to the boatwhistle could be disadvantageous to a receptive female, increasing confusion without adding useful information."

"Even though the boatwhistie is one of the most intense fish sounds (40 dB re: 1dyn/cm^2, equivalent to 114 dB re: 0.0002 dyn/cm^2; Tavolga, 1971) it may not be audible over long distances. Sound does not propagate in water shallower than about a quarter of a wavelength over a rigid bottom (Officer, 1958; Gerald. 1971). Toadfish commonly call in 1m deep water, and a 200 Hz sound (a typical boatwhistle fundamental frequency) has a wavelength of 7.5 m."

"Considering the acoustically complicated nature of a shallow water habitat. our propagation curves for tones are suprisingly regular. Transmission losses were greatest in the first few meters, where spreading loss is maximal, and then declined somewhat more slowly (Figs I and 2, Table I). Transmission loss was large in all cases. Attenuation of 200 Hz tones ranged from 23 to 34.5 dB (Fig. I) between 1 and 4 m from the source at Site 1 and averaged 21.5 dB at site 2 (Fig.2). Absorption coefficients for these data are 6.1, 9.4 and 5.6dB/m respectively."

"Similar to tones, playbacks of boatwhistles attenuated rapidly and were lost in the noise beyond 5 m from the source (Figs 4 and 5). At Site 1 the SPL of a boatwhistle with a fundamental frequency of 220 Hz dropped 17 dB between 1 and 5 m (Fig. 4), yielding an absorption coefficient of 2.75 dB/m. The signal was band-passed filtered to separately measure the SPL of the fundamental frequency and second harmonic (440 Hz)."

"Tavolga (1964),in a review article on fish sound production, mentions some measurements he made on Upsanus ruu boatwhistles in Florida. He stated that bottom type and distance from the calling fish influenced the harmonic structure of the call and that a 250 Hz fundamental was usually lost at a distance of 10m. Recording depth was not given."

"Toadfish produce sounds that do not propagate well in their habitat, and a mismatch between the courtship call and the auditory system suggests short-range communication."

"The fundamental frequency and discrete harmonics of the boatwhistle are determined by contraction rate of the paired swimbladder muscles (Skoglund, 1961) and apparently not by resonance properties of the bladder (Fine. 1983). The fundamental frequency changes seasonally from under 150 Hz to over 250 Hz (Fine, 1978; Fine et ul., 1982)"

"Toadfish boatwhistle commonly in shallow water, and occasionally we tiave found calling males in depths of less than a foot."

"While the toadfish appears unique among species studied in not having neurons tuned to its mating call (Fine and Capranica, 1979; Fine, 19X1), it is by no means the only species in which selection pressures have apparently not acted to maximize communication range."

"Male oyster toadfish (Opsunus tau) commonly produce their courtship boatwhistle call in water so shallow that it might not support acoustic propagation of low frequency sound."

Observation Environment Quotes

"Tones, boatvvhistles or broadband noise (+4dB from 30Hz upward). either prerecorded on a Nakamichi 550 stereo casette recorder or produced by an audio oscillator or noise generator, were amplified, attenuated and broadcast underwater from a Navy .I4 sound projector (Aat +4dB from 40 to 10,000 Hz, below 40 Hz it falls off at 6dB/octave). Sounds were recorded unfiltered with a Wilcoxon H-505 omnidirectional hydrophone onto another Nakamichi 550 recorder."

Behaviour Description Quotes

"By 200Hz, a typical fundamental frequency of the courtship boatwhistle call (Fine, l978), its threshold has declined over 20dB. An intensely suprathreshold call from a nearby fish is necessary to facilitate a calling male (Fish and Offuiitt, 1972)."

"While the toadfish appears unique among species studied in not having neurons tuned to its mating call (Fine and Capranica, 1979; Fine, 19X1), it is by no means the only species in which selection pressures have apparently not acted to maximize communication range."

"Male oyster toadfish (Opsunus tau) commonly produce their courtship boatwhistle call in water so shallow that it might not support acoustic propagation of low frequency sound."

Sound Name Quotes

"By 200Hz, a typical fundamental frequency of the courtship boatwhistle call (Fine, l978), its threshold has declined over 20dB. An intensely suprathreshold call from a nearby fish is necessary to facilitate a calling male (Fish and Offuiitt, 1972)."

"Toadfish may be unable to localize far-field sounds. Since males often call in dense choruses, increased sensitivity to the boatwhistle could be disadvantageous to a receptive female, increasing confusion without adding useful information. "

"Toadfish commonly call in 1m deep water, and a 200 Hz sound (a typical boatwhistle fundamental frequency) has a wavelength of 7.5 m."

"The fundamental frequency and discrete harmonics of the boatwhistle are determined by contraction rate of the paired swimbladder muscles (Skoglund, 1961) and apparently not by resonance properties of the bladder (Fine. 1983). The fundamental frequency changes seasonally from under 150 Hz to over 250 Hz (Fine, 1978; Fine et ul., 1982)"

"Male oyster toadfish (Opsunus tau) commonly produce their courtship boatwhistle call in water so shallow that it might not support acoustic propagation of low frequency sound."