Full Description

"We performed a control experiment to test this assumption, using a grunt produced by a toadfish and a train of pulses produced by a croaker (Micropogonius undulatus) restrained in a net under water."

"The acoustic pressure of the croaker sounds was 114 dB (re: 1 µPa at 1 m) in recordings from both the free hydrophone and the one within the terra cotta tile; similarly, the toadfish grunt was 124 dB from both hydrophones. Further, power spectra from the two hydrophones appeared identical for each species. Spectra for the croaker (Fig. 5) are illustrated because they include higher frequency energy, which is more likely to be affected by the terra cotta. Note that the small peak at 1380 Hz had a relative value of –47 dB in both recordings."

Observation Environment Quotes

"Because of the small dimensions of the terra cotta tile compared with the acoustic wavelength of 200 Hz under water, we assumed that the tile (density 1.925 g/cm3; Brady 1977) would not have a major effect on the sound field, particularly at the low frequencies utilized by the toadfish. We performed a control experiment to test this assumption, using a grunt produced by a toadfish and a train of pulses produced by a croaker (Micropogonius undulatus) restrained in a net under water."

Behaviour Description Quotes

"We performed a control experiment to test this assumption, using a grunt produced by a toadfish and a train of pulses produced by a croaker (Micropogonius undulatus) restrained in a net under water."

Sound Name Quotes

"We performed a control experiment to test this assumption, using a grunt produced by a toadfish and a train of pulses produced by a croaker (Micropogonius undulatus) restrained in a net under water."

Full Description

"To determine if the directionality of toadfish sound is consistent with this hypothesis, boatwhistle advertisement calls of individually identified males were recorded in the York River, Virginia, by means of two calibrated hydrophones and a waterproof recording system: one hydrophone was fixed 1 m in front of the fish and the second was roving. Boatwhistles in the horizontal plane propagated in a modified omnidirectional pattern that was bilaterally symmetrical. The mean sound pressure was 126 dB re: 1 µPa at 0°. The sound pressure level decreased by approximately 1 dB at ±45°, after which levels increased to 180°, averaging 3–6 dB greater behind (mean 130 dB) than directly in front of the fish."

"Grunt levels overlapped but were slightly lower than boatwhistle values."

"Both sexes produce an agonistic grunt call, which is a variable series of short-duration pulses with a fundamental frequency of 90–110 Hz (Fish 1954; Tavolga 1958; Gray and Winn 1961). The boatwhistle is a long-duration tonal call with a fundamental frequency commonly over 200 Hz and harmonic bands at multiples of the fundamental frequency (Fish 1954; Tavolga 1958; Winn 1964; Fine 1978). The boatwhistle is produced exclusively by nesting males (Gray and Winn 1961) and functions to advertise the male’s presence to other males and females; playbacks of the boatwhistle have been shown to attract gravid females and increase the calling rate of territorial males (Winn 1967, 1972; Fish 1972)."

"The acoustic pressure of the croaker sounds was 114 dB (re: 1 µPa at 1 m) in recordings from both the free hydrophone and the one within the terra cotta tile; similarly, the toadfish grunt was 124 dB from both hydrophones. Further, power spectra from the two hydrophones appeared identical for each species. Spectra for the croaker (Fig. 5) are illustrated because they include higher frequency energy, which is more likely to be affected by the terra cotta. Note that the small peak at 1380 Hz had a relative value of –47 dB in both recordings."

"The absolute sound pressure was 126 ± 1.2 dB re: 1 µPa, with a range of 13 dB for all fish (Table 1), and the ranges for individual fish varied from 4 to 9 dB, with a median range of 4 dB. Fish 1 had the largest range, with a minimum level of 119 dB and two calls with maximum levels of 127 and 128 dB. Excluding these three calls, the remaining 67 boatwhistles ranged from 122 to 126 dB, similar to data from the other fish. Maximum values recorded 1 m behind the fish averaged 130 dB and ranged from 127 to 134 dB. Fundamental frequencies varied from 230 to 270 Hz, but the ranges for individual fish were much smaller, 0 Hz in three fish and 10 Hz in two fish. Duration averaged 286 ms, ranging from 175 to 407 ms, and there were clear differences in duration between individuals. The range of durations for individuals averaged 119 ms and ranged from 64 to 164 ms. Coefficients of variation (the standard deviation divided by the mean) for fundamental frequency and sound pressure level were quite stereotyped, averaging 0.6 and 0.9%, respectively; duration was considerably more variable, averaging 8.1%. Four of the individuals produced one or more grunts during the recording period (Table 2), with a mean level of 123 dB. The sound pressure levels of the single grunt and the mean boatwhistle for fish 3 were identical at 130 dB, and the other three fish averaged 4 dB less for the grunt than for the boatwhistle, although there was some overlap in three of the four cases (Tables 1, 2)."

"Source levels of grunts have not been previously measured in situ, although grunts evoked by electrical stimulation of the brain (Fine and Perini 1994) and spontaneous grunts of different-sized fish held in a net in air have been measured in the laboratory (Waybright et al. 1990). Source levels of grunts in our small sample tended to overlap but were somewhat weaker than levels of boatwhistles. The range of 5–10 dB for individual fish is similar to the range of 3–13 dB recorded for spontaneous grunts by Waybright et al. (1990). Grunt fundamental frequencies averaging 134–170 Hz are also in the range for spontaneous grunts (100–185 Hz) of York River fish, and are higher than the values of 90–110 Hz traditionally found for grunts (Fish 1954; Tavolga 1958). Fundamental frequencies varied by up to 50 Hz for an individual, which is clearly greater than the range in most fish recorded in the laboratory. Durations of grunts between 48 and 147 ms likewise overlap with the range of 44–300 ms for electrically evoked burst grunts."

"The high frequencies (230–270 Hz) recorded in this study are typical of late-season values, when water temperatures are high (Fine 1978). The stereotypy of the fundamental frequency (3 of 5 fish produced a single frequency and two fish varied over 10 Hz) suggests the existence of a precise timing mechanism in the pacemaker nucleus."

Observation Environment Quotes

"Toadfish were recruited to terra cotta drainage tiles (35 cm in length, 9.8 cm in internal diameter, and 1.1 cm thick), which males entered voluntarily and used as nesting shelters. Tiles were placed in rows at a depth of 1–2 m on a flat sandy substrate. Depth variation within a 1-m radius around the tile was typically less than 0.1 m, and the bottom was free of acoustic obstacles such as rocks, debris, or pier pilings. Although the fish were free to move, the internal diameter of the tile was small enough to restrict lateral movements of large nesting males (see Results)."

Behaviour Description Quotes

"To determine if the directionality of toadfish sound is consistent with this hypothesis, boatwhistle advertisement calls of individually identified males were recorded in the York River, Virginia, by means of two calibrated hydrophones and a waterproof recording system: one hydrophone was fixed 1 m in front of the fish and the second was roving. "

" Both sexes produce an agonistic grunt call, which is a variable series of short-duration pulses with a fundamental frequency of 90–110 Hz (Fish 1954; Tavolga 1958; Gray and Winn 1961). The boatwhistle is a long-duration tonal call with a fundamental frequency commonly over 200 Hz and harmonic bands at multiples of the fundamental frequency (Fish 1954; Tavolga 1958; Winn 1964; Fine 1978). The boatwhistle is produced exclusively by nesting males (Gray and Winn 1961) and functions to advertise the male’s presence to other males and females; playbacks of the boatwhistle have been shown to attract gravid females and increase the calling rate of territorial males (Winn 1967, 1972; Fish 1972)."

Sound Name Quotes

"To determine if the directionality of toadfish sound is consistent with this hypothesis, boatwhistle advertisement calls of individually identified males were recorded in the York River, Virginia, by means of two calibrated hydrophones and a waterproof recording system: one hydrophone was fixed 1 m in front of the fish and the second was roving. "

"Grunt levels overlapped but were slightly lower than boatwhistle values."

" Both sexes produce an agonistic grunt call, which is a variable series of short-duration pulses with a fundamental frequency of 90–110 Hz (Fish 1954; Tavolga 1958; Gray and Winn 1961). The boatwhistle is a long-duration tonal call with a fundamental frequency commonly over 200 Hz and harmonic bands at multiples of the fundamental frequency (Fish 1954; Tavolga 1958; Winn 1964; Fine 1978). The boatwhistle is produced exclusively by nesting males (Gray and Winn 1961) and functions to advertise the male’s presence to other males and females; playbacks of the boatwhistle have been shown to attract gravid females and increase the calling rate of territorial males (Winn 1967, 1972; Fish 1972)."

"Individual toadfish were isolated from the background chorus by moving the hydrophone to maximize sound amplitude."