Full Description

"One was a low-frequency rumble with a prominent energy peak at approximately 150 Hz. The other was a clearly distinguishable call made by individual or small groups of red drum. Calls of individual red drum were detected along most sections of all transects. There were extensive areas along each transect where no close drumming was heard and where drumming rates were primarily low (<16 calls/min). Calls were detected in both extensive clusters and isolated occurrences along the transects. The distribution of drumming fish suggests that some, if not most, spawning takes place among widely dispersed individuals as opposed to highly aggregated groups. Only 7% of the 1-min summaries recorded high drumming rates (16 calls/min), and even these typically were produced by only a few individuals. Most low drumming rates were produced by a single fish."

"Red drum produce low-frequency sounds that are described as knocks (Fish and Mowbray 1970) or drumming (Guest and Lasswell 1978). Although Guest and Lasswell (1978) found that the ‘‘dominant energy’’ of their red drum recordings from a tank was around 240–1,000 Hz, I have found the fundamental frequency of red drum calls obtained from unconstrained fish in the field to consistently be around 140–160 Hz, as did Luczkovich et al. (1999). Each call consists of a variable number of pulses or knocks that are repeated at a range of pulse repetition rates (Guest and Lasswell 1978 from laboratory observations; my unpublished data from field observations)."

"Guest and Lasswell (1978) reported that the maximum call rate of red drum was around 16 calls/min."

"The most intense drumming activity occurred between 1830 and 2130 hours. Little drumming was heard after 2130 hours at Matagorda Island or San Jose Island transect A. Low and high drumming rates were distributed throughout this time period without any temporal pattern."

Observation Environment Quotes

"Based on the 1999 survey results, the 2000 study was designed to concentrate on the 10-m depth contour between the Aransas Pass tidal inlet and Pass Cavallo, the next major tidal inlet 93 km to the north. Three transects were established: one near each inlet and one at the midpoint between them. Transects were surveyed (1 night/transect) between 28 September and 5 October. The towed array was composed of eight hydrophones in an 80-m cable connected to a 200-m towing cable and towed at approximately 7.4 km/h (4 knots) from the 32-m (105-ft) stern-trawler Longhorn."

Behaviour Description Quotes

"Male red drum make loud, characteristic sounds associated with courtship and spawning (Guest and Lasswell 1978); these sounds offer another potential means of locating spawning sites."

"Courtship-associated sounds (calls) of red drum could clearly be detected by ear on the towed array recordings."

Sound Name Quotes

"One was a low-frequency rumble with a prominent energy peak at approximately 150 Hz. The other was a clearly distinguishable call made by individual or small groups of red drum. Calls of individual red drum were detected along most sections of all transects. There were extensive areas along each transect where no close drumming was heard and where drumming rates were primarily low (<16 calls/min). Calls were detected in both extensive clusters and isolated occurrences along the transects. The distribution of drumming fish suggests that some, if not most, spawning takes place among widely dispersed individuals as opposed to highly aggregated groups. Only 7% of the 1-min summaries recorded high drumming rates (16 calls/min), and even these typically were produced by only a few individuals. Most low drumming rates were produced by a single fish."

"Red drum produce low-frequency sounds that are described as knocks (Fish and Mowbray 1970) or drumming (Guest and Lasswell 1978). Although Guest and Lasswell (1978) found that the ‘‘dominant energy’’ of their red drum recordings from a tank was around 240–1,000 Hz, I have found the fundamental frequency of red drum calls obtained from unconstrained fish in the field to consistently be around 140–160 Hz, as did Luczkovich et al. (1999). Each call consists of a variable number of pulses or knocks that are repeated at a range of pulse repetition rates (Guest and Lasswell 1978 from laboratory observations; my unpublished data from field observations)."