665 
AbStr3Ct.— Young-of-the-year(YOY) 
bluefish, Pomatomus saltatrix, were 
collected during the summers of 1992 
and 1993 in the Hudson River estuary 
with beach seine, surface trawl, and gill 
nets. The temporal and spatial patterns 
of catch-per-unit-of-effort (CPUE) and 
gut-fullness values were used to infer 
bluefish movement and feeding periods, 
respectively. Estimates of daily ration 
were made from gut-fullness values and 
previously published estimates of gas- 
tric evacuation rate. Nearshore beach- 
seine CPUE was highest during day 
collections and lowest at night. Offshore 
gill-net CPUE was highest during cre- 
puscular or night periods and lowest 
during day sets. Hence, YOY bluefish 
appear to occupy nearshore environ- 
ments during the day and move away 
from shore at night. Gut-fullness val- 
ues for bluefish captured with beach 
seines were highest at diurnal and cre- 
puscular periods and declined at night; 
however, there were indications of night 
feeding on some dates. The magnitude 
and pattern of daily ration estimates 
of YOY bluefish in the Hudson River 
estuary were similar to values mea- 
sured in previous studies with other 
methods. Interannual differences in the 
magnitude of daily ration were ob- 
served and may be a result of day-to- 
day variation in feeding or differences 
in available prey type and size. Clu- 
peids, striped bass, and bay anchovy 
were important prey in 1992, whereas 
striped bass, bay anchovy, and Atlan- 
tic silversides were the dominant prey 
of YOY bluefish in 1993. Improved un- 
derstanding of the spatial and tempo- 
ral patterns of bluefish feeding, as well 
as fine-scale temporal resolution of es- 
timates of bluefish consumption rates, 
will aid in assessing the impact ofYOY 
bluefish predation on fish populations 
within the Hudson River estuary. 
Manuscript accepted 28 May 1997. 
Fishery Bulletin 95:665-679 (1997). 
Movements, feeding periods, and daily 
ration of piscivorous young-of-the-year 
bluefish, Pomatomus saltatrix, 
in the Hudson River estuary* 
Jeffrey A. Buckel** 
David O. Conover 
Marine Sciences Research Center 
State University of New York 
Stony Brook, New York 1 1 794-5000 
**Present address: James J. Howard Marine Sciences Laboratory 
National Marine Fisheries Service, NOAA 
74 Magruder Road 
Highlands, New Jersey 07732 
E-mail address: jbuckel@sh.nmfs.gov 
The movements of fishes are con- 
trolled by both biotic and abiotic 
phenomena. In estuaries, fish may 
move in relation to the availability 
of prey and to reduce the risk of pre- 
dation, as well as in response to fluc- 
tuations in light, tide, salinity, tem- 
perature, and dissolved oxygen lev- 
els (Miller and Dunn, 1980). Fish 
distribution is often controlled by 
the interacting effects of these fac- 
tors (Miller and Dunn, 1980; Gibson 
et al., 1996). An understanding of 
the factors that govern the move- 
ments and distributions of predators 
and prey is prerequisite to quantify- 
ing predator-prey interactions. 
The bluefish, Pomatomus salt- 
atrix, is a marine piscivorous preda- 
tor of circumglobal distribution. On 
the U.S. east coast, spawning occurs 
offshore over the continental shelf, 
but young-of-the-year (YOY) mi- 
grate abruptly into estuaries at ~60 
mm fork length (Kendall and Wal- 
ford, 1979; Nyman and Conover, 
1988; McBride and Conover, 1991; 
Juanes and Conover, 1995). Blue- 
fish spawned in the South Atlantic 
Bight in the spring (spring-spawned) 
are advected northward in waters 
associated with the Gulf Stream 
(Hare and Cowen, 1996) and move 
into New York-New Jersey estuaries 
in June (Nyman and Conover, 1988; 
McBride and Conover, 1991). A sec- 
ond wave of recruits made up of sum- 
mer-spawned fish (spawned in the 
Middle Atlantic Bight) appear in 
nearshore waters in mid- to late- 
summer. The habitat shift from oce- 
anic waters to estuarine areas co- 
incides with a shift from feeding that 
is zooplanktivorous to one that is pi- 
scivorous (Marks and Conover, 1993). 
This study is part of a larger 
project designed to estimate the 
predatory impact that YOY bluefish 
have on their piscine prey popula- 
tions in the Hudson River estuary. 
Young-of-the-year bluefish are 
known to prey on larval and juve- 
nile fishes in marine embayments 
and estuaries along the U.S. east 
coast (Grant, 1962; Friedland et al., 
1988; Juanes et al., 1993; Creaser 
and Perkins, 1994; Hartman and 
Brandt, 1995a; Juanes and Cono- 
ver, 1995). In the Hudson River es- 
tuary, YOY bluefish prey include the 
young of several resource species 
such as striped bass, Morone sax- 
* Contribution 1067 of the Marine Sciences 
Research Center, State University of New 
York, Stony Brook. 
