Full Description

"Spotted seatrout produced three distinct call types characterized as ‘‘drums,’’ ‘‘grunts,’’ and ‘‘staccatos.’’ Spotted seatrout calling increased as the light cycle shifted from 13.5 to 14.5 h of light, and the temperature increased to 27.7 _C. Calling decreased once the temperature fell below 27.7 _C, and the light cycle shifted to 12 h of light. These temperature and light patterns followed the natural reproductive season observed in wild spotted seatrout in the Southeast United States. Spotted seatrout exhibited daily rhythms in calling. Acoustic signaling began once the lights turned off, and calling reached maximum activity approximately 3 h later. Eggs were released only on evenings in which spotted seatrout were calling. In all tanks, spotted seatrout were more likely to spawn when male fish called more frequently. A positive relationship between SPL and the number of eggs collected was found in Tanks 1 and 3."

"Our findings indicate that acoustic metrics can predict spawning potential."

"It was estimated that spotted seatrout in age classes 1–3 spawn every 4.7, 4.2, and 4 days, respectively, in Charleston Harbor, South Carolina (Roumillat & Brouwer, 2004). Tabb (1966) was the first to report that male spotted seatrout use acoustic signals that are associated with reproductive activity. Mok & Gilmore (1983) discovered that male spotted seatrout produce four major sound types, which were all recorded at spawning sites in Indian River Lagoon, Florida. These calls were designated as (i) a ‘‘grunt’’ followed by a series of ‘‘knocks’’, (ii) ‘‘aggregated grunts,’’ (iii) ‘‘long grunt’’; and (iv) a rapid series of short pulses known as the ‘‘staccato.’’ Females do not have a sonic muscle and do not produce sound (Mok & Gilmore, 1983). It is well known that spotted seatrout form large mating aggregations (i.e., leks). These aggregations produce higher sound pressure levels (>50 dB–90 dB re 1 mPa at 3 m) as compared to the levels of individual callers (<30 dB re 1 mPa at 3 m) (Gilmore, 2003). It is speculated that this combined acoustic energy derived from a male aggregation increases the number of receptive spawning females attracted to the lek (Gilmore, 2003)."

"We determined that Fmin = 541 Hz, which was different than the expected peak frequency of spotted seatrout chorusing in the wild (i.e., _239 Hz; E Montie, 2016, unpublished data); thus possible resonance was minimal."

"In our captive study, we grouped the ‘‘grunt followed by knocks’’ and ‘‘aggregated grunts’’ observed by Mok & Gilmore (1983) together because of their similarity in call structure and described these calls as ‘‘drums’’ to avoid confusion with the ‘‘grunt.’’ We classified the ‘‘long grunt’’ as the ‘‘grunt,’’ while the ‘‘staccato’’ strictly followed the description provided by Mok & Gilmore (1983)."

"What we report here is that most of the acoustic energy of calling occurred between 50 and 1,000 Hz (Figs. 2E–2G). A staccato call was characterized as having multiple pulses (n > 5) (Figs. 2A, 2B, 2E). A grunt call was composed of a single pulse displaying multiple harmonics (Figs. 2A, 2C, 2F). A drum call was composed of one to five pulses (Figs. 2A, 2D, 2G). In all tanks, the number of drums, grunts, and staccatos were positively correlated with each other (Pearson Correlation Test; P < 0:05 for all comparisons). Sound pressure levels during periods when fish were calling were higher than the background noise levels when spotted seatrout were not calling (Figs. 3B, 3E, 3H). In all tanks, drums were the most frequently produced followed by grunts and then staccatos (Table 2; Fig. 4). Sound pressure level and the total number of calls (i.e., sum of drums, grunts, and staccatos) were positively correlated (Pearson Correlation Test; r = 0:917, P < 0:01 for Tank 1; r = 0:688, P < 0:01 for Tank 2; and r = 0:457, P < 0:01 for Tank 3)."

"Maximal calling occurred when the photoperiod shifted to 14.5 h of light, and the temperature increased to 27.7 _C."

"In all tanks, spotted seatrout showed daily rhythms in sound production (Fig. 5). Generally, calling began once the lights turned off (i.e., 17:45). The highest number of drums occurred at 21:20 in Tank 1; 21:00 in Tank 2; and 20:40 in Tank 3 (Fig. 5). The number of grunts, staccatos, and received SPLs followed similar patterns."

"In this captive experiment, our data indicated that sound production served an important function in courtship."

"On many evenings, male spotted seatrout did call and no spawning was observed, but spawning never happened without asignificant increase insound production."

"In the present captive study, all of these call types (i.e., ‘‘drums,’’ ‘‘grunts,’’ and ‘‘staccatos’’) were associated with courtship behavior and spawning."

"Generally, rapid rises in temperature increased calling rates, while rapid declines in temperature decreased calling."

"In the wild, there is some evidence that spotted seatrout calling and spawning are associated with the lunar cycle. Gilmore jr (1994) discovered that spotted seatrout calling occurred most often on the full moon or within three to four days after the full moon."

"These findings may indicate that having more males that are acoustically active in a spawning aggregation are key factors in enhancing reproductive output and sustaining populations."

"In studies with wild spotted seatrout in the Barataria, Caminada, and eastern Timbalier Bay systems of Louisiana, tows downstream of drumming aggregations contained two to three times more eggs in comparison to tows upstream (Saucier & Baltz, 1993)."

Observation Environment Quotes

"Acoustic recorders (i.e., DSG-Oceans) were placed in three laboratory tanks to record underwater sound over an entire, simulated reproductive season. We enumerated the number of calls, calculated the received sound pressure level, and counted the number of eggs every morning in each tank."

Behaviour Description Quotes

"Our findings indicate that acoustic metrics can predict spawning potential."

"In all tanks, spotted seatrout were more likely to spawn when male fish called more frequently. A positive relationship between SPL and the number of eggs collected was found in Tanks 1 and 3.' 'It was estimated that spotted seatrout in age classes 1–3 spawn every 4.7, 4.2, and 4 days, respectively, in Charleston Harbor, South Carolina (Roumillat & Brouwer, 2004). Tabb (1966) was the first to report that male spotted seatrout use acoustic signals that are associated with reproductive activity. Mok & Gilmore (1983) discovered that male spotted seatrout produce four major sound types, which were all recorded at spawning sites in Indian River Lagoon, Florida. These calls were designated as (i) a ‘‘grunt’’ followed by a series of ‘‘knocks’’, (ii) ‘‘aggregated grunts,’’ (iii) ‘‘long grunt’’; and (iv) a rapid series of short pulses known as the ‘‘staccato.’’ Females do not have a sonic muscle and do not produce sound (Mok & Gilmore, 1983). It is well known that spotted seatrout form large mating aggregations (i.e., leks). These aggregations produce higher sound pressure levels (>50 dB–90 dB re 1 mPa at 3 m) as compared to the levels of individual callers (<30 dB re 1 mPa at 3 m) (Gilmore, 2003). It is speculated that this combined acoustic energy derived from a male aggregation increases the number of receptive spawning females attracted to the lek (Gilmore, 2003). "

"In this captive experiment, our data indicated that sound production served an important function in courtship. "

"In the present captive study, all of these call types (i.e., ‘‘drums,’’ ‘‘grunts,’’ and ‘‘staccatos’’) were associated with courtship behavior and spawning."

Sound Name Quotes

"Spotted seatrout produced three distinct call types characterized as ‘‘drums,’’ ‘‘grunts,’’ and ‘‘staccatos.’’ "

" It was estimated that spotted seatrout in age classes 1–3 spawn every 4.7, 4.2, and 4 days, respectively, in Charleston Harbor, South Carolina (Roumillat & Brouwer, 2004). Tabb (1966) was the first to report that male spotted seatrout use acoustic signals that are associated with reproductive activity. Mok & Gilmore (1983) discovered that male spotted seatrout produce four major sound types, which were all recorded at spawning sites in Indian River Lagoon, Florida. These calls were designated as (i) a ‘‘grunt’’ followed by a series of ‘‘knocks’’, (ii) ‘‘aggregated grunts,’’ (iii) ‘‘long grunt’’; and (iv) a rapid series of short pulses known as the ‘‘staccato.’’ Females do not have a sonic muscle and do not produce sound (Mok & Gilmore, 1983). It is well known that spotted seatrout form large mating aggregations (i.e., leks). These aggregations produce higher sound pressure levels (>50 dB–90 dB re 1 mPa at 3 m) as compared to the levels of individual callers (<30 dB re 1 mPa at 3 m) (Gilmore, 2003). It is speculated that this combined acoustic energy derived from a male aggregation increases the number of receptive spawning females attracted to the lek (Gilmore, 2003). "

"We determined that Fmin D 541 Hz, which was different than the expected peak frequency of spotted seatrout chorusing in the wild (i.e., _239 Hz; E Montie, 2016, unpublished data); thus possible resonance was minimal."

"The ‘wav’ file with the most abundant calls was used to determine the mean number of pulses in a ‘‘staccato’’ call as well as the mean duration for that specific day. "

"What we report here is that most of the acoustic energy of calling occurred between 50 and 1,000 Hz (Figs. 2E–2G). A staccato call was characterized as having multiple pulses (n > 5) (Figs. 2A, 2B, 2E). A grunt call was composed of a single pulse displaying multiple harmonics (Figs. 2A, 2C, 2F). A drum call was composed of one to five pulses (Figs. 2A, 2D, 2G). In all tanks, the number of drums, grunts, and staccatos were positively correlated with each other (Pearson Correlation Test; P < 0:05 for all comparisons). Sound pressure levels during periods when fish were calling were higher than the background noise levels when spotted seatrout were not calling (Figs. 3B, 3E, 3H). In all tanks, drums were the most frequently produced followed by grunts and then staccatos (Table 2; Fig. 4). Sound pressure level and the total number of calls (i.e., sum of drums, grunts, and staccatos) were positively correlated (Pearson Correlation Test; r = 0:917, P < 0:01 for Tank 1; r = 0:688, P < 0:01 for Tank 2; and r = 0:457, P < 0:01 for Tank 3)."