Capossela et al : Migratory and within-estuary behaviors of adult Paralichthys dentatus of the southern mid-Atlantic Bight 
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had a later mean dispersal date than the fish that did 
not use the lower channels. Divergent patterns of be- 
havior have been observed in other acoustic telemetry 
studies on Summer Flounder. In the Mullica River- 
Great Bay estuary, up to 80% of fish remained in the 
lower bay near the inlet where they were tagged (Sack- 
ett et al. 2008), but several fish did move into the river 
system. At an artificial reef in the Chesapeake Bay, 
larger Summer Flounder were more likely to stay in 
close proximity to the reef structure than were smaller 
fish (Henderson, 2012). 
The behavior of Summer Flounder in estuaries has 
been described as sedentary with only minor activity 
before fall emigration (Desfosse, 1995; Sackett et al., 
2008; Henderson, 2012). This description characterized 
Summer Flounder in the Wachapreague lagoon sys- 
tem, where fish rarely exhibited large-scale movements 
(100s of meters) between receivers in the upper chan- 
nels. However, passive telemetry cannot capture small- 
scale movements adequately, and fish may have been 
active within smaller areas (<100s of meters). Active 
tracking of Summer Flounder in the Mullica River- 
Great Bay estuary revealed that fish were in motion 
within small areas (0.18 km 2 ) for most of the time that 
they were observed and that small-scale movements in 
deeper waters (-8.5 m) were not related to tidal cur- 
rents or temperature (Sackett et al., 2008). Small-scale 
activity was attributed to feeding, competition, or ter- 
ritorial behaviors (Sackett et al., 2008). We did not ob- 
serve significant effects of temperature or tidal stage 
on large-scale (100s of meters) fish activity in the up- 
per channels during the residency period. Fish in these 
regions may have an ample supply of prey delivered 
by the currents and, therefore, may not need to make 
large-scale movements or use energetically beneficial 
tidal conditions (e.g., Wirjoatmodjo and Pitcher, 1984; 
Szedlmayer and Able, 1993; Miller, 2010). 
During the residency period, fish activity in the up- 
per channels of the Wachapreague lagoon system was 
significantly greater at night than during the day. 
Laboratory-based observations revealed that Sum- 
mer Flounder are more active during the day (Olla et 
al., 1972), but such studies considered activity on a 
much smaller scale (e.g., in a seawater tank that was 
10.6x4.5x3.0 m). Similar large-scale (200-400 m) activ- 
ity of Summer Flounder in the Chesapeake Bay also 
was greatest at night and influenced by lunar phase 
(Henderson, 2012). Although benthic foragers (such as 
Summer Flounder) are generally more light sensitive 
than are other estuarine pelagic piscivores (Horodysky 
et al., 2010), the foraging ability of visual predators 
is most likely limited at night. Therefore, night-time 
movements may be associated with behaviors other 
than prey localization and feeding. 
Conclusions 
One of the benefits of acoustic telemetry is the ability 
to identify variation in behavior within a population 
that renders a species differentially vulnerable to es- 
tuarine conditions, predation, and harvesting. Differ- 
ences and similarities in behavior patterns observed 
for a species by multiple researchers can be used to 
identify factors that influence such patterns. Our study 
confirms that, although the life history and migration 
dynamics of Summer Flounder are well described, in- 
dividual fish are not uniform in their use of estuaries 
during summer residencies throughout the MAB. 
Residence times vary by estuary, indicating that lo- 
cal conditions are important to population success. Fish 
size may also effect how long Summer Flounder remain 
in an estuarine system. As was found in a northern 
MAB estuary, most tagged Summer Flounder in the 
Wachapreague lagoon system were sedentary over 100s 
of meters and remained in deeper (>3 m) waters near 
the inlet until they undertook the spawning migration 
(although a small number of individuals did make use 
of other regions). 
Further research is needed to consider the effects 
of release location and year on distribution of tagged 
Summer Flounder. Studies that combine acoustic moni- 
toring with the distribution and availability of preda- 
tors and prey may help explain observed distributions. 
Establishment of a network of strategic acoustic moni- 
toring stations within multiple MAB estuaries and 
along the continental shelf would enable monitoring of 
fish in these habitats and could help clarify the fate of 
early or temporary emigrants (Grothues et al., 2005; 
Able and Grothues, 2007). A better understanding of 
Summer Flounder habitat preferences and behaviors in 
estuaries along their range of distribution is essential 
for protecting areas that promote year-class strength 
and spawning success. 
Acknowledgments 
We thank the following individuals for their assistance 
with this study: R Bushnell, D. Gauthier, M. Hender- 
son, J. Smith, and L. Smith. We acknowledge M. Luck- 
enbach, S. Fate, R. Bonniwell, and the support staff of 
the Virginia Institute of Marine Science Eastern Shore 
Laboratory. We also thank T. Targett for his comments 
on earlier drafts of this manuscript and D. Fox for 
sharing detections from Delaware Bay. Funding for 
this project was provided by the Oceanside Conserva- 
tion Co., Inc., Student Research Grant, and the Eastern 
Shore Graduate Research Grant. This is contribution 
3251 from the Virginia Institute of Marine Science, 
College of William & Mary. 
