196 
Fishery Bulletin 111(2) 
r 14.28 48 
14 27 30 
14.21 54 
14 20 24 
7/1/2007 
3/1/2008 
Figure 5 
The proportion of Summer Flounder (Paralichthys dentatus ) that dis- 
persed from (^) and returned to (■) the Wachapreague lagoon system 
from 8 June 2007 to 7 April 2008 (when the last fish was detected return- 
ing), on the basis of the Kaplan-Meier estimator. Photoperiod (day length 
in hours; gray line) is also plotted. Confidence intervals have been omit- 
ted for clarity. 
detected in the upper channels, but only 27% (12 in- 
dividuals) of the fish that were detected in the upper 
channels were also detected in the lower channels. This 
finding indicates that the majority of fish released in 
the upper channels (73%, 32 individuals) remained near 
the release site in the upper channels until dispersal. 
The proportion of time and the proportion of fish in 
the upper channels were significantly greater during 
the residency period than during the emigration period 
(Table 2; z tlme =17.0, P<0.05; z fish =4.2, P<0.05). Use of 
the lower channels was greatest during the emigration 
period, both in terms of proportions of time spent in 
these habitats and the number of fish detected (Ta- 
ble 2; z time =14.6, P<0.05; z fish =2.6, P<0.05). Most fish 
(85%) detected in the lower channels occupied the up- 
per channels for a mean of 132 ±14 days before they 
were detected in the lower channels. Fish detected in 
both the upper and lower channels had a later mean 
emigration date (15 November 2007) than that of fish 
that did not use the lower channels (24 August 2007). 
Only 4% (2 individuals) of Summer Flounder briefly 
occupied the tidal flat between October and December 
2007 (6 ±5 days, range: 1-11 days). Summer Flounder 
did not appear to regularly occupy the additional por- 
tions of the Wachapreague system monitored by the 
supplementary receivers. Only 7% (3 individuals) of 
Summer Flounder were detected by these receivers, 
and the mean residency was 6 ±4 days (range: 0.2-13 
days). Fish presence was, however, likely underesti- 
mated because of the limited coverage and the shorter 
period of receiver deployment. 
Although the inlet region was fre- 
quented by Summer Flounder over the 
course of our study (Fig. 6B), fish spent 
a smaller proportion of time at the in- 
let (2%) than in the upper and lower 
channels (97%; Table 1). The mean 
time at the inlet was 2 ±0.6 days. 
Not surprisingly, both the proportions 
of time and fish at the inlet were 
greatest during the emigration period 
(Table 2; Ztime=4.9, P< 0.05; z fish =3.0, 
P<0.05). 
Only 5 Summer Flounder in the up- 
per channels moved between adjacent 
or nonadjacent receivers more than 
10 times during the residency period. 
The mean observed activity did not 
vary significantly by week (x 2 =19.06, 
P=0.33), but it did vary significantly 
with time of day; the mean activity 
index was significantly greater dur- 
ing night than during day (x 2 =6.13, 
P<0.05). Individuals appeared most ac- 
tive during the flood tide or during the 
slack tide before ebb, but differences in 
mean activity among tidal stages were 
not statistically significant (x 2 =6.97, 
P=0.07). Activity also was not affected 
by differences in mean temperature for a given tidal 
stage (x 2 =0.46, P= 0.55). 
Discussion 
Migratory behaviors 
The observed timing of Summer Flounder dispersal 
from the Wachapreague system (October though Janu- 
ary) is consistent with the established seasonal pro- 
gression of spawning migration from north to south 
(Smith, 1973; Morse, 1981; Kraus and Musick, 2001; 
Sackett et al., 2007). It most closely matches the re- 
ported timing of emigration for Summer Flounder in 
the nearby Chesapeake Bay. Summer Flounder pri- 
marily emigrate from Chesapeake Bay from October 
through December, and some fish emigrate as late as 
February (Desfosse, 1995; Henderson, 2012). In New 
Jersey’s Mullica River-Great Bay estuary (-250 km 
to the north), acoustically tagged fish generally emi- 
grated earlier — between August and December (Able et 
al., 1990; Roundtree and Able, 1992b; Szedlmayer and 
Able, 1993). By mid-September, 75% of tagged Summer 
Flounder had dispersed from a study site on the inner 
shelf near New Jersey (Fabrizio et al. 3 ). In contrast, 
3 Fabrizio, M. C., J. P. Pessutti, J. P. Manderson, A. F. Drohan, 
and B. A. Phelan. 2005. Use of the historic area remedia- 
tion site by black sea bass and summer flounder. Northeast 
Fish. Sci. Cent Ref. Doc. 05-06, 95 p. 
