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CC2 and may have accommodated fewer fish especially 
if (male) black drum establish territories which require 
some space between individuals (Locascio, 2010). Anoth- 
er interesting pattern was apparent in the correlation 
of synoptically recorded data from all sites. The higher 
correlations among the CC sites for chorus timing re- 
vealed that acoustic signaling by black drum may occur 
in the context of a communication network, where the 
calling behavior initiated by some individuals elicits 
responses from others and propagates throughout the 
population. We were not able to confirm this pattern in 
the Punta Gorda canal system because of having only 
one study site there. It is also possible that some over- 
arching environmental condition(s) helped initiate call- 
ing at each of the three Cape Coral sites. These results 
emphasize the need that complementary environmental 
data be collected along with acoustic data. 
In two previous studies, hydrophone recordings were 
used to investigate black drum spawning behavior. 
Saucier and Baltz (1993) conducted mobile hydrophone 
surveys in coastal southeast Louisiana and recorded 
black drum calls from January through April, in 15.0° 
to 24.0°C water temperatures, and peak sound pro- 
duction in March and April. The highest SPLs were 
recorded in 20.8°C (±1.01) and 18.9°C (±1.43) water 
temperatures for presumed large and moderate-size 
black drum aggregations, respectively. Mok and Gilm- 
ore (1983) also conducted mobile hydrophone surveys 
and recorded black drum during the winter and early 
spring in Indian River Lagoon, Florida. They reported 
maximal sound production during January in 18.0° to 
20.0°C water temperatures and no sound production 
occurred below 15.0°C. Although water temperature did 
not reach the apparent 15.0°C lower limit for sound pro- 
duction in our study, the temperature range over which 
black drum were recorded (bottom: 17-24°C, surface: 
17.5-26°C) and the range associated with highest levels 
of sound production (18-22°C) are consistent with these 
previous studies. Black drum are a demersal species 
which would account for the higher correlation between 
SPL and bottom water temperatures in this study. The 
higher correlation between surface water temperatures 
at a one day lag and sound production during the latter 
half of the season could indicate that black drum were 
higher in the water column or possibly that this was 
a response to increasing photoperiod, which would be 
positively correlated with temperature. 
The range of water temperatures associated with 
black drum sound production has also been reported 
for spawning. Peters and McMichael (1990) back-cal- 
culated larval black drum birthdates from collections 
made in Tampa Bay, FL, and estimated that water 
temperatures were 16-20°C during the early part of the 
spawning season and 21-24°C during peak season. Holt 
et al. (1988) collected black drum eggs in water tem- 
peratures of 18-25°C in the Gulf of Mexico near Port 
Aransas, Texas. Within the geographic range of black 
drum in U.S. waters, spawning has been documented 
to occur later in the year at more northern latitudes 
(Murphy and Taylor, 1989) but apparently within the 
