150 
Fishery Bulletin 115(2) 
A 
New Jersey 
Navesink River 
Age-1 + striped bass, 2006 o i km 2 3 
40.38°N- 
40.36°N- 
Age-1+ striped bass, 2007 
T-1- 
I I Low activity 
Moderate activity 
m High activity 
=;=:= Reach 
Plots of home ranges derived from acoustic detections of ultrasonically tagged fish in the Navesink River in 
New Jersey: age-l+ striped bass (Morone saxatilis) in (A) 2006 and (B) 2007 and weakfish {Cynoscion regalis) 
in (C) 2006 and (D) 2007. Parallel dashed lines denote reaches 1-4 of the estuary. 
upper river rather than in a nearby channel. The front 
was well developed in summer 2007, and we were able 
to test the hypothesis. The data for age-0 and age-l+ 
bluefish conformed to the hypothesis at that time, but 
data for weakfish did not. Among forage fish, only At¬ 
lantic silverside was caught exclusively at the salinity 
front; other species were caught at both the front sta¬ 
tion and the channel station. Atlantic silverside feed on 
zooplankton, such as copepods, ostracods, mysids, and 
the young stages of many estuarine organisms (Collette 
and Klein-MacPhee, 2002), and zooplankton productiv¬ 
ity is known to be concentrated at salinity fronts (Mor¬ 
gan et al., 1997; Martino and Houde, 2010). More At¬ 
lantic silverside were found in stomachs of fish collected 
at the salinity front than in stomachs of fish captured 
at the channel. In and around the front, chlorophyll-a 
concentration was highest as expected, and high turbid¬ 
ity was limited to locations upriver from the front. The 
abundance of Atlantic menhaden particularly is associ¬ 
ated with patches of high chlorophyll-a concentration 
that result from phytoplankton blooms (Friedland et 
al., 1996; Collette and Klein-MacPhee, 2002); however, 
Atlantic menhaden were collected at both the front and 
channel stations in summer. In fall, in the absence of 
a defined hydrographic front, Atlantic menhaden were 
abundant at both stations. 
The estuarine turbidity maximum does not control 
the availability of all prey resources that support the 
3 predator species that we investigated. Atlantic men¬ 
haden and the majority of other forage fish were not 
limited to the area of the estuarine turbidity maxi¬ 
mum. Invertebrate prey, particularly blue crabs and 
sand shrimp, were almost as important as Atlantic 
menhaden by percent weight in the predator diets in 
spring and summer. These 2 invertebrate prey species 
are abundant throughout the Navesink River (Meise 
and Stehlik, 2003; senior author, unpubl. data). We be¬ 
lieve that, in addition to the main salinity front, other 
areas in the Navesink River have hydrodynamics and 
benthic habitats that are suitable for supporting the 3 
predator species. 
We found that the diets of bluefish and weakfish in 
2007 generally contained the same major prey taxa. 
Other researchers have recognized dietary overlap 
with these 2 species and with striped bass (Hartman 
and Brandt, 1995; Wuenschel et al., 2013). The fish 
species that are the major prey customarily consumed 
by bluefish, weakfish, and striped bass in mid-Atlantic 
estuaries and nearshore areas are bay anchovy, At¬ 
lantic menhaden, and Atlantic silverside (Juanes and 
Conover, 1994; Buckel and Conover, 1997; Taylor et al., 
2007). 
