Mather et al.: Use of non-natal estuaries by migratory Morone saxatilis in summer 
337 
gren and Lieberman, 1978), but these coastal migrants 
were larger (>450 mm; Dorazio et al., 1994). We provide 
evidence that small adult striped bass, captured in Mas- 
sachusetts during the summer, were also part of the 
coastal migratory stocks. 
These recaptures of migratory fish at the location 
where they were tagged were much higher than our 
model predicted if movements were random. In this 
study, during the first summer after tagging, many 
striped bass were recaptured in a relatively small, local 
area (<20 km 2 ). Striped bass recaptured in the Great 
Marsh (77%) used only 0.73% of the New England coast- 
line available for feeding by migratory striped bass. 
Striped bass recaptured along the Massachusetts coast 
(100%) used only 25.1% of the New England coastline. 
Furthermore, no fish tagged and released in Massa- 
chusetts in summer was recaptured in other New Eng- 
land states in summer, in spite of high fishing effort. 
These results indicate that some highly mobile striped 
bass that have traveled hundreds of kilometers to feed, 
cease their mobile lifestyle, and remain in relatively 
local areas (i.e., the Great Marsh or the Massachusetts 
coast) for a prolonged period in summer. Summer is an 
important period for food acquisition, and understand- 
ing why striped bass may choose one feeding area over 
another is critical to managing a fish that uses multiple 
habitats separated by hundreds of kilometers. Migra- 
tion patterns of striped bass may be linked to different 
conditions across habitats. High temperatures, low oxy- 
gen, and inadequate prey may deter striped bass from 
remaining in specific habitats (Coutant and Benson, 
1990; Hartman and Brandt, 1995). In addition, growth 
can be higher in some locations than in others (Welsh 
et al., 2003). As such, migration may have evolved to 
move striped bass away from poor conditions (e.g., high 
temperature, low oxygen, or poor prey conditions) or 
towards better foraging conditions (e.g., seasonally 
abundant prey, moderate water temperatures). Prey 
resources may be available during a longer period of 
physiologically suitable conditions in northern estuaries 
than in southern estuaries. This feature could facilitate 
prolonged use of feeding habitats in northern estuaries 
in summer. 
The degree of site fidelity observed was surprisingly 
high given that this highly mobile fish migrates hun- 
dreds of kilometers annually, encounters tens of estu- 
aries, and has the potential for multidirectional move- 
ment. Site fidelity has been documented in freshwater 
(Buzby and Deegan, 2000; McCairns and Fox, 2004), 
marine (Thorrold et al., 2001; Szedlmayer and Schro- 
epfer, 2005), and anadromous fish (Stewart et al., 2004; 
Minakawa and Kraft, 2005). However, many of these ex- 
amples of site fidelity are within physically constrained 
riverine systems. Some site fidelity has been observed 
for striped bass in freshwater (Jackson and Hightow- 
er, 2001), but it has only recently been examined for 
coastal migrants (Wingate and Secor, 2007; this study). 
Home range, or the habitats used over a period of 
time (day, season, year), can be a useful way of think- 
ing about a species distribution and its relationship to 
environmental conditions. The size of a home range can 
vary with sex, season, availability of resources, body 
size, feeding strategy, and group size (Baker, 1978). 
Although home range can be measured for any animal, 
the concept of home range may make little sense for 
animals that roam widely. For migratory fish that feed 
throughout their entire range or that use a large ocean 
feeding area, the concept of a feeding home range may 
have limited utility. However, a feeding home range pro- 
vides a useful conceptual framework for understanding 
movements of fish like striped bass that may migrate 
between discrete spawning and feeding areas. This 
discrete feeding home range of individual fish can also 
have implications for fisheries management. Migratory 
fish that stay in a specific area for a prolonged time 
may adopt different feeding strategies based on previ- 
ous experience in the estuary, and these feeding strate- 
gies may result in spatially explicit patterns of growth. 
In addition, local fishing pressure may influence feeding 
groups such that migratory fish that stay in a local area 
for a prolonged period may be caught and released more 
frequently, resulting in higher mortality. Consequently, 
knowing the movements of individual migratory fish in 
foraging areas is crucial for appropriate management. 
Acknowledgments 
This project was administered through the Massachu- 
setts Cooperative Fish and Wildlife Research Unit. The 
Massachusetts Cooperative Fish and Wildlife Research 
Unit is an association among the U.S. Geological Survey; 
University of Massachusetts Department of Natural 
Resources Conservation; Massachusetts Division of 
Marine Fisheries; Massachusetts Division of Fisheries 
and Wildlife, and the Wildlife Management Institute. 
J. Hightower and D. Parrish provided useful comments. 
We extend special thanks to the Plum Island Long Term 
Ecological Research Site (OCE 9726921) for generously 
providing lodging and the USFWS for compiling the 
tag database. 
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