Manderson et al.: Residence time and habitat duration for predators in a small mid-Atlantic estuary 
153 
D 
Freshwater discharge log (rp 3 s" 1 +1) 
Figure 5 
Plots from logistic generalized additive mixed models showing partial deviance effects 
of freshwater discharge from the Swimming River on the residence of the 3 predator 
species in the Navesink River (see Table 3) tagged in our study in 2006 and 2007: (A) 
Striped Bass (Morone saxatilis), (B) Weakfish ( Cynoscion regalis), and (C) age-0+ and (D) 
age-1 Bluefish ( Pomatomus saltatrix). Vertical lines crossing the horizontal line at 0.0 
indicate boundaries between positive and negative effects, and shaded areas represent 
±2 standard-error confidence band. 
telemetry study indicates that high abundances reflect 
relatively long-term residence times for predators <500 
mm TL rather than a rapid flux of many transient in- 
dividuals through the ecosystem. Long-term residences 
of individual fishes with little straying indicates that 
temperature, oxygen, and prey resources persist at 
suitable levels in the small tributary for relatively long 
periods. 
Predators with small body sizes had longer residen- 
cies and, therefore, appeared to be supported longer 
by habitat resources in the small ecosystem than were 
larger individuals. Large Striped Bass and Bluefish 
(>500 mm TL) used the tributary for a few days to a 
few weeks during the spring. Large Weakfish (>400 mm 
TL) released later in the summer were also relatively 
transient. Smaller age-l+ Bluefish remained in the es- 
tuary for intermediate lengths of time. Finally, age-0 
Bluefish and small age-l-i- Weakfish (<400 mm TL) had 
the longest residence times (median residence=29 d and 
~40 d) that were probably underestimated in our study. 
Although Weakfish were common in gill nets in May (L. 
Stehlik and senior author, unpubl. data), we were able 
to capture them only with hook and line in early July 
after their diets had shifted from invertebrate to fish 
prey. Small Bluefish (20-30 mm TL), which cannot be 
surgically tagged, are collected in Navesink River as 
early as June in beach seines and fine mesh gillnets 
(L. Stehlik, unpubl. data). Small Weakfish and Blue- 
fish were, therefore, resident in the Navesink River 
probably for much longer periods than those that we 
measured. Our observations of long residences of small 
predator cohorts in the Navesink River are consistent 
with observations made in larger estuarine ecosystems 
(Grothues and Able, 2007; Taylor et al., 2007; Wingate 
and Secor, 2007; Mather et al., 2009; Turnure, 2010). 
The size-dependent patterns of estuarine residence 
time for the 3 studied predators may have been relat- 
ed to size-dependent requirements for prey resources. 
