Dunton et at: Abundance and distribution of Aapenser oxyrinchus within the Northwest Atlantic Ocean 
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75°0'W 70°0'W 65°0'W 
Figure 1 
Coverage area of the Maine-New Hampshire inshore bottom trawl 
survey (ME-NH), Massachusetts Division of Marine Fisheries 
bottom trawl survey (MADMF), New York bottom trawl survey 
(NYBTS), New Jersey Department of Environmental Protec- 
tion finfish survey (NJDEP), and the National Marine Fisheries 
Service bottom trawl surveys (NMFS). The area covered by the 
NMFS survey is represented by horizontal stripes. All other 
surveys are represented by shades of gray. 
lantic sturgeon inhabit shallow in- 
shore areas of the continental shelf 
(Stein et al., 2004a, 2004b). More re- 
cently, some long-term fishery-inde- 
pendent data have revealed that juve- 
nile Atlantic sturgeon use the inshore 
waters of North Carolina during the 
winter months (Laney et al., 2007). 
Additionally, there are a handful of 
reported cases of Atlantic sturgeon 
captured in deeper offshore areas (Ti- 
moshkin, 1968; Collins and Smith, 
1997; Stein et al., 2004a, 2004b). 
Still, more information is needed to 
guide management towards the best 
mechanisms to protect the remaining 
Atlantic sturgeon. 
One contributing factor to the con- 
tinued decline of Atlantic sturgeon 
populations is incidental capture of 
juveniles in non-target marine fish- 
eries (Collins et al., 1996; Stein et 
al., 2004a). Most of the current by- 
catch mortality occurs in gill and 
drift net fisheries (Stein et al., 
2004a; ASSRT 3 ). Discard mortality 
from trawl fisheries is hard to esti- 
mate because few direct mortalities 
are observed. Mortality however may be 
very high due to delayed effects on cap- 
tured individuals (Davis, 2002; Broadhurst 
et al., 2006). Because Atlantic sturgeon do 
not reach maturity until 12-14 years of age 
and reproductive output increases later in 
life (Van Eenennaam and Doroshov, 1998), 
reducing mortality on juveniles is key to 
restoring depleted populations (Boreman, 
1997). 
In order to adequately protect both juvenile and adult 
Atlantic sturgeon, marine distributional patterns must 
be identified such that essential habitat may be pro- 
tected. In this article we use data from five different 
oceanic fishery-independent surveys to reveal the sea- 
sonal distribution, abundance, and habitat use of Atlan- 
tic sturgeon along the Northwest Atlantic continental 
shelf from Cape Hatteras, NC, to the Gulf of Maine 
(GOM) (Fig. 1). 
Materials and methods 
We analyzed data from five fishery-independent sur- 
veys conducted by the following agencies: 1) National 
3 Atlantic Sturgeon Status Review Team (ASSRT). 2007. Status 
review of Atlantic sturgeon ( Acipenser oxyrinchus oxyrin- 
chus), 174 p. Report to National Marine Fisheries Service, 
Northeast Regional Office, Gloucester, MA, 23 Feb 2007. 
National Oceanic and Atmospheric Science Administration, 
Washington D.C. 
Marine Fisheries Service (NMFS); 2) New Jersey 
Department of Environmental Protection (NJDEP); 
3) Maine Department of Marine Resources and the 
New Hampshire Fish and Game Department (ME- 
NH); 4), Massachusetts Division of Marine Fisheries 
(MADMF); and 5) New York Bottom Trawl Survey 
(NYBTS) (Fig. 1). Catch per unit of effort (CPUE) was 
calculated (number of fish per tow) for each survey and 
depth (m). Depth (m), temperature (°C), and salinity 
(ppt) data were obtained from the NMFS, NJDEP, and 
NYBTS databases to estimate environmental prefer- 
ences. For all surveys, except the MADMF, depth was 
calculated as the average between the maximum and 
minimum values. Depth values used in the MADMF 
analysis are the depth at which the tow started. For 
all surveys, tows were analyzed for each season, which 
are defined as winter (21 Dec-20 Mar), spring (21 
Mar-20 Jun), summer (21 Jun-20 Sept), and fall (21 
Sep-20 Dec). Specifics of each survey are discussed 
in detail below. 
Because male and female Atlantic sturgeon mature 
at different size ranges (van Eenennaam and Doroshov, 
