Capossela et al.: Migratory and within-estuary behaviors of adult Paralichthys dentatus of the southern mid-Atlantic Bight 
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MB Upper channel 
l l Lower channel 
Inlet 
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Nov Dec Jan 
Figure 6 
(A) The monthly mean proportion of time that Summer Floun- 
der ( Paralichthys dentatus) occupied the upper channels, lower 
channels, and Wachapreague Inlet in the Wachapreague lagoon 
system from June 2007 to January 2008. For a given month, 
the proportion of time that individual fish occupied each re- 
gion was calculated as the ratio of the amount of time that 
a fish resided in a region in relation to the total time it was 
detected that month, with proportions for a month adding to 
1. iB) The monthly proportion of individual Summer Flounder 
detected in the upper channels, lower channels, and Wacha- 
preague Inlet. The proportion of fish that occupied a region 
was determined as the ratio of the number of individual fish 
identified in that region to the number of fish detected in the 
system that month. The sum of the proportions of fish in each 
region could be <1 if not all fish could be assigned objectively 
to a region in any given month. The sum of the proportions of 
fish that used each region could be >1 if a single fish occupied 
more than 1 region in any given month. 
75% of tagged fish in the Wachapreague lagoon 
system did not disperse until early December, 
and mean residence time was 1.5 times longer 
(130 days, June-January) than the time previ- 
ously reported for the Mullica River— Great Bay 
estuary (86 days, May-December; Sackett et ah, 
2008). Seasonal changes in temperature strong- 
ly influenced residence time, as indicated by the 
increase in dispersal rates with the seasonal 
decline in temperature. A similar relationship 
between water temperature and seasonal mi- 
gration was observed in winter flounder through 
the use of passive acoustic telemetry (DeCelles 
and Cadrin, 2010). 
On the basis of the life history of Summer 
Flounder, fish that dispersed from the Wacha- 
preague lagoon system during the emigration 
period (after 11 October 2007) were most likely 
moving offshore to spawn. Our study revealed 
that smaller fish were more likely than larger 
fish to leave during the emigration period, con- 
firming previous reports that larger Summer 
Flounder commence spawning migrations ear- 
lier than smaller fish (Smith, 1973). Summer 
Flounder that dispersed from the Wachapreague 
system during the emigration period had signifi- 
cantly greater odds of returning to the system 
the following year than did those fish that dis- 
persed during the residency period. 
The percentage of fish returning to the 
Wachapreague lagoon system (36%) was similar 
to the percentage reported for more northern 
estuaries (25-35% and 39% in New York and 
New Jersey, respectively; Poole, 1962; Sackett et 
ah, 2007). Unlike returns in a previous mark- 
recapture study (Desfosse, 1995), returns to the 
Wachapreague lagoon system were not detected 
after April, although the expected battery life of 
our transmitters would have permitted detec- 
tion through July 2008. Summer Flounder did 
return to the Wachapreague lagoon system as 
early as February, indicating that some fish may 
actually remain in this system for upwards of 
10 months (i.e., from February to the following 
December). 
Acoustic telemetry permitted the identifi- 
cation of early and temporary emigrants from 
estuaries in this and a previous study (Sackett 
et ah, 2007). It is possible that early emigrants 
migrate to the outer continental shelf to spawn, 
but the timing of these events is much earlier 
(typically in the early summer) than the tim- 
ing reported for the spawning migration of this 
species. Fish that disperse early or temporarily 
may instead occupy habitats on the inner continental 
shelf or in other estuaries before final emigration to 
the outer continental shelf to spawn. On the basis of 
the confirmed observation of a single fish that was sub- 
sequently detected in Delaware Bay approximately 2 
weeks after tagging, there is at least some movement 
of Summer Flounder between coastal estuarine sys- 
tems within the same summer. Previous mark-recap- 
ture studies have also indicated that Summer Flounder 
move from Virginia to more northern MAB estuaries 
