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Fishery Bulletin 113(2) 
Figure 5 
Diel variation in distance from area of localized daytime residency 
(ALDR) for individual weakfish ( Cynoscion regalis) detected by using 
active telemetry (from 30 June to 31 July 31 2008). All weakfish (n=9), 
except one fish (ID 100), were originally tagged at Deep Point in the 
lower Mullica River and distances (km) from that site were pooled and 
averaged by 2-h bins for each tagged fish. Error bars represent stan- 
dard error of means for individuals and sample sizes are displayed 
above bars. Gray boxes indicate approximate nighttime periods (1930- 
0430 hours). The ALDR was defined for each individual in the evalu- 
ation of diel movements as the seasonal area of localized residency 
(ALR) by weekly active tracking events (3 or more consecutive weekly 
detections within 500 m of each other). The ALDR corresponded to the 
original release site (Deep Point) for all fish, except one fish (ID 100). 
The area below the horizontal dotted line indicates distances (<0.5 km) 
within the defined ALDR. For sampling locations, see Figure 1. For 
details for individual tagged weakfish, refer to Table 2. 
(1800-2000), indicating that initiation of nighttime 
movements was dynamic among individuals (e.g., the 
fish with ID 103). 
Nighttime is also the period when peak weakfish 
spawning occurs (Taylor and Villoso, 1994). Concur- 
rent research in the study area during active tracking 
events confirmed nightly weakfish drumming, indicat- 
ing that spawning may have occurred during the track- 
ing period (Turnure, 2010). These results confirm ob- 
servations from previous studies of weakfish movement 
in Delaware Bay during the sundown period that was 
related to spawning activity (Connaughton and Taylor, 
1994). In this study, fish facing inshore (presumably 
in prespawning mode) were frequently caught in gill 
nets during the early evening hours and in the later 
evening (presumably after spawning), fish were caught 
facing offshore. Further, few fish were caught in gill 
nets during the early morning and early afternoon, 
likely the time when weakfish decreased their move- 
ments (Connaughton and Taylor, 1994). Those authors 
also examined the drumming pattern 
of weakfish and noted that the highest 
level of spawning vocalizations occurred 
inshore during early evening (Connaugh- 
ton and Taylor, 1995). 
Diel movements and day-night chang- 
es in use of space are common among 
other sciaenid species (e.g., red drum: 
Dresser and Kneib, 2007; sea raven: 
Alos and Cabanellas-Reboredo, 2012; and 
Japanese croaker: Naesje et al., 2012) 
and in other families (e.g., white stur- 
geon ( Acipenser transmontanus): Pars- 
ley et al., 2008; red snapper ( Lutjanus 
campechanus ): Topping and Szedlmayer, 
2011) but this article provides the first 
description of similar behavior in weak- 
fish. Juvenile weakfish movements in 
relation to diel-cycling of hypoxia events 
were observed during summer in a small 
tributary of the Delaware Bay (Tyler and 
Targett, 2007; Brady and Targett, 2013) 
and modeled (Brady et al., 2009). During 
the former study, juveniles exhibited a 
daily escape response (~1 km) in areas 
where hypoxia events occurred (dissolved 
oxygen <2 mg/L), indicating that move- 
ment patterns could be more dynamic in 
affected systems where daily fluctuations 
in dissolved oxygen are common. The re- 
sults from the tracking study described 
here represent weakfish movement pat- 
terns within a relatively undisturbed 
estuary where low dissolved oxygen is 
infrequent. 
The dynamics of movements in adult 
weakfish appear to be related to scaling 
over seasonal and diel time frames, and 
these results represent new evidence of 
the affinity of adult weakfish to specific 
estuarine localities and of their ability to return to 
them from relatively large distances within an estuary 
across ecologically relevant time scales. Although the 
site fidelity of other adult fishes (e.g., summer floun- 
der ( Paralichthys dentatus ): Capossela et al., 2013), 
including those fishes previously studied in this sys- 
tem (striped bass: Ng et al., 2007; summer flounder: 
Sackett et al., 2007) has been observed in small estua- 
rine systems and site fidelity has been quantified at 
the regional estuarine scale for weakfish (Thorrold et 
al., 2001), fine-scale behaviors have not been previously 
quantified in adult weakfish. 
In further studies of weakfish estuarine movements, 
one step would be to reexamine the previous model of 
natal homing and site fidelity in adult weakfish (Thorr- 
old et al., 2001) at smaller spatial scales. The long-term 
spatial memory needed to enable a fish to return back 
to relatively small areas (Fukumori et al., 2010) on a 
yearly basis was not observed in weakfish (Turnure et 
al., in press), but a similar ability to relocate to an 
