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Fishery Bulletin 106(4) 
may 1) exit the Gulf Stream and settle north of North 
Carolina, 2) continue across the North Atlantic in the 
Gulf Stream and possibly settle in the eastern Atlantic, 
3) complete a circuit of the North Atlantic until they 
return to the western North Atlantic, or 4) ultimately 
not contribute to their respective populations (McBride 
and Able, 1998; Ross et al., 2007). Even though Sargas- 
sum and associated fishes can be transported into the 
Middle Atlantic Bight or farther north (Dooley, 1972), 
the first alternative is unlikely given that most demer- 
sal fish species using Sargassum are of tropical or warm 
temperate origins and are not established as adults 
north of North Carolina (Winge, 1923; McBride and 
Able, 1998). The second alternative, also suggested by 
Dooley (1972), seems possible because fifty-three (66%) 
of the 80 total species collected off North Carolina are 
established in the eastern Atlantic (Hureau and Monod, 
1973a, 1973b), but the link (if any) between these fishes 
and those in the western Atlantic remains unclear. The 
third alternative seems least likely because most of the 
fishes collected in the surface waters do not have larval 
or juvenile periods long enough to complete a circuit of 
the Atlantic basin (Ross et al., 2007). It seems likely 
that many of the fishes remaining in the Sargassum 
north of Cape Hatteras eventually perish. Pelagic spe- 
cies (e.g., carangids, exocoetids, Coryphaena spp.) are 
probably not as restricted and can emigrate from Sar- 
gassum habitat to open-water habitat over a broader 
geographic area. Despite the fact that huge numbers of 
fishes use Sargassu?ii habitat in the early life stages, 
data are lacking regarding its role in transporting ju- 
veniles to inshore habitats, in settlement processes, and 
to what extent Sargassum- associated fishes contribute 
to their respective populations. 
Sargassum is an unusual and difficult habitat to sam- 
ple, and no ideal sampling method has yet been applied. 
The algae and their medium (water) are in constant 
motion, and the density and structure of the habitat 
are constantly changing. One cannot predict exactly 
when or where Sargassum will occur and, unlike static 
habitats, it cannot be mapped. Thus, it is generally 
difficult to collect a known number or type of samples 
from this habitat. Sampling in this study was balanced 
between day and night, but for the above reasons was 
not balanced between the two habitats. Sampling the 
Sargassum fauna includes collecting the habitat as well, 
and the density of the habitat coupled with the three 
dimensional layering of associated nekton reduce the 
efficiencies of most sampling gear (especially dip nets). 
The approach in this study of using a large neuston 
net to consistently encompass a substantial volume of 
surface water allowed for large enough samples over a 
wide range of algal densities. 
There is little doubt that Sargassum habitat consti- 
tutes an important and unique marine ecosystem. It 
provides a feeding area for many large pelagic fishes, 
marine mammals, seabirds, and sea turtles. Sargassum 
may enhance early survival of many fishes by protecting 
them from predation and by concentrating prey, thus 
providing a unique nursery habitat in an otherwise 
relatively barren area of the western North Atlantic 
Ocean. For these reasons, Sargassum was designated 
as essential fish habitat by the South Atlantic Fisheries 
Management Council. The role of Sargassum in trans- 
porting juveniles to inshore habitats and subsequent im- 
pacts on population recruitment should be investigated. 
Acknowledgments 
This research was partially funded by grants from the 
National Oceanic and Atmospheric Administration Office 
of Ocean Exploration (to S. W. Ross, lead PI). The 1999 
and 2000 cruises were partially supported by the North 
Carolina Legislature (to S. W. Ross). The August 2001 
RV Cape Hatteras cruise was sponsored by the Duke/ 
University of North Carolina Oceanographic Consortium 
(to S. W. Ross). United States Geological Survey, Florida 
Integrated Science Center (through K. J. Sulak) provided 
personnel and logistics support. We thank T. Lankford 
for assistance with statistics, D. Weaver for recording 
the underwater video, and A. Quattrini, M. Mclver, and 
anonymous reviewers for constructive suggestions on an 
earlier draft of the manuscript. 
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