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Fishery Bulletin 111(2) 
Therefore, variation in emigration timing may exist not 
only by latitude but also among individual fish within 
a system. Some adult Summer Flounder have been 
known to return to the same estuary in subsequent 
years (Poole, 1962; Sackett et al., 2007; Henderson, 
2012), but factors that influence site fidelity in Sum- 
mer Flounder are not well understood. 
Acoustic telemetry has also been used to identify 
variations in Summer Flounder within-estuary activity. 
For example, Summer Flounder in the Mullica River- 
Great Bay estuary primarily used the lower bay (near 
the inlet), but some fish resided in other areas (Sack- 
ett et al., 2008). Likewise, most fish remained in the 
Mullica River-Great Bay estuary until emigration to 
the outer shelf, but several adults exited and entered 
the system multiple times (i.e., exhibited temporary 
emigration). Similar patterns were observed in the 
Chesapeake Bay (southern MAB), where some adults 
remained sedentary and resided at structured sites for 
long periods of time, and others were more active and 
traveled long distances (Henderson, 2012). 
The continuation of acoustic studies is necessary to 
identify similarities and differences in behavioral pat- 
terns between regions and to investigate the drivers 
behind these patterns. Our objectives for this study 
were to use acoustic telemetry to describe the migra- 
tory and within-estuary behaviors of adult Summer 
Flounder from a previously unstudied lagoon system in 
the southern portion of the MAB. The lagoon systems 
off Virginia’s Eastern Shore are subject to large fluc- 
tuations in temperature typical of most MAB systems 
(0-30°C), but they differ from larger estuaries in that 
they are shallow (mean depth <3 m), well-mixed, and 
polyhaline areas. These lagoon systems are a nursery 
ground for juvenile Summer Flounder (Schwartz, 1964; 
Norcross and Wyanski, 1994; Desfosse, 1995; Kraus 
and Musick, 2001), but they also support a large num- 
ber of adults and an active recreational fishery (Rich- 
ards and Castagna, 1970). Previous descriptions of the 
use of our chosen lagoon system by Summer Flounder 
have been limited to descriptions of juvenile habitat 
preferences (Wyanski, 1990; Norcross and Wyanski, 
1994) and adult migration patterns determined by tra- 
ditional mark-recapture methods (Kraus and Musick, 
2001; Desfosse, 1995). 
We used the data from our acoustic telemetry study 
to determine 1) dispersal and return rates, 2) duration 
of residency, 3) spatiotemporal distribution, and 4) ac- 
tivity of fish within the system. Because tidal stage, 
time of day, and temperature all have been associated 
with flatfish activity (Olla et al., 1972; Casterlin and 
Reynolds, 1982; Wirjoatmodjo and Pitcher, 1984; Malloy 
and Targett, 1991; Szedlmayer and Able, 1993; Hender- 
son, 2012), these factors were considered in our exami- 
nation of within-estuary activity. We also analyzed the 
effects of seasonal temperature, photoperiod, and fish 
size on dispersal, returns, and residency times (Smith, 
1973; Able and Kaiser, 1994). 
Materials and methods 
Study site 
The estuarine lagoon system near Wachapreague, Vir- 
ginia, resides behind a series of low barrier islands and 
primarily connects with the Atlantic Ocean through 
Wachapreague Inlet (Fig. 1). The 2 main channels 
leading from Wachapreague Inlet divide into smaller 
channels that cut through marsh areas (dominated by 
smooth cordgrass [Spartina alterniflora]) before they 
open into large, shallow tidal flats. Channels were 
identified as areas -3-12 m deep, and tidal flats were 
identified as areas <3 m deep. As with most seaside 
lagoon systems in Virginia, the system near Wachapre- 
ague is characterized by restricted access to the ocean, 
minimal freshwater input, and a moderate tidal range 
(1.2-1. 4 m; NOAA Center for Operational Oceano- 
graphic Products and Services, http://tidesandcurrents. 
noaa.gov/tides07/tab2ec2b. html#44). Strong currents 
are typical because of natural constrictions at the in- 
let and in the channels (Conrath, 2005), although cur- 
rents generally dissipate with distance from the inlet. 
Sediment type follows the energy gradient, with coarse 
sand within and near the inlet, and progressively finer 
(muddy) sediments at greater distances from the inlet 
(Wyanski, 1990). 
We divided our study area into 4 regions (Fig. 1): 
1 Wachapreague Inlet — the primary point of ingress 
and egress of fish characterized by depths of 6-15 m 
and strong currents; the inlet is about 625 m wide. 
2 Upper channels — the channel leading north from 
Wachapreague Inlet and its divergent channels. 
3 Lower channels — the channel leading south from 
Wachapreague Inlet and its divergent channels. 
4 Tidal flats (also known locally as bays ) — the shal- 
lowest bodies of water included in our study. Al- 
though several tidal flats are present in this area, 
only Swash Bay was included in our study area be- 
cause we could monitor the movements of Summer 
Flounder into and out of this area. 
We recorded environmental conditions in the in- 
let, channels, and tidal flat from 8 June 2007 to 29 
July 2008 with 3 YSI 6920-O 1 multiparameter water- 
quality sondes (YSI, Inc., Yellow Springs, OH; Fig.l), 
which recorded temperatures and dissolved oxygen con- 
centrations once per hour. Sondes were replaced with 
calibrated units every 1-2 weeks in the summer and (as 
fouling diminished) every 2-4 weeks thereafter. Errone- 
ous recordings due to membrane fouling, battery failure, 
and calibration drift were removed from the data set. 
Data from the water-quality sondes confirmed that dis- 
solved oxygen concentrations generally remained above 
the critical oxygen level (27.2%, 2.0 mg O 2 L _1 ) for adult 
Summer Flounder at typical summer bottom-water 
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