James et al.: Overwinter habitat use of young-of-the-year Carcharodon carcharias 
Shark ID 
SST (°C) @WS1 @WSs11 
High: 30 © WS2 OWS13 
jee OWS7 @WS16 
__ @WS8 @WS17 
imum Low:0 ~ WS9 AMATOS 
76°W 7T4°W 72°W 
’ YOY White Shark 
EFH 
Atlantic 
Ocean 
YOY White Shark 
Overwinter Habitat 
Mid-Atlantic Shark 
Closure Area 
0 150 300 km 
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Figure 1 
Maps showing (A) daily positions (colored circles) and (B) the minimum convex 
polygon that delineates the area of cumulative activity space (i.e., home range; 
stippled area) based on detections of tags attached to or implanted in 9 young- 
of-the-year (YOY) white sharks (Carcharodon carcharias) tracked off the East 
Coast of the United States from December through April during 2016-2018. 
In panel A, positions are shown over average winter sea-surface temperatures 
(SST) and the 100-m, 200-m, and 2000-m isobaths (gray lines). Triangles indicate 
the locations of acoustic receivers in the Mid-Atlantic Acoustic Telemetry Obser- 
vation System (MATOS), and the open arrow denotes the location and direction 
of the Gulf Stream. Shark IDs correspond to individual sharks described in Shaw 
et al. (2021). In panel B, the area of cumulative activity space of tracked sharks 
is compared to the 200-m isobath (gray line), to the current essential fish habitat 
(EFH) area designated by the National Marine Fisheries Service for YOY white 
sharks (hatched area), and to the Mid-Atlantic Shark Closure Area (polygon out- 
lined with a thick black line). The black star in the EFH denotes the location 
where sharks were tagged in August 2016 and 2017. 
7\ 
Chl-a concentrations of 0.2-6.1 mg/m? 
(mean: 1.0 mg/m? [SD 0.9]). 
Overwinter distribution relative to 
key fisheries management boundaries 
varied. Positions of YOY white sharks 
did not overlap at all with the current 
EFH designated for this life stage, and 
they actually extended up to 960 km 
beyond the current EFH boundary 
(Fig. 1B). In contrast, the overwinter 
distribution of YOY white sharks signifi- 
cantly overlapped with the Mid-Atlantic 
Shark Closure Area. Over half (54%) of 
the daily positions indicate that tagged 
sharks were within the boundaries of the 
closure area during the time the closure 
was in effect (from 1 January through 
July 31). 
Discussion 
The results of this study improve the 
understanding of overwinter distribution 
and habitat use of YOY white sharks in 
the Northwest Atlantic Ocean, and this 
advancement is important because YOY 
is a life stage that has been historically 
little studied in this region (Curtis et al., 
2018; Shaw et al., 2021). Preliminarily, 
results from analysis of tracking data for 
9 individuals from 2 cohorts indicate that 
YOY white sharks make seasonal migra- 
tions to the coastal waters of North and 
South Carolina during their first winter 
period (from December through April). 
The combination of both satellite and 
acoustic tag technologies provided more 
insight into overwinter habitat use than 
either technology would have on its own, 
as has been recently reported for habitat 
use of YOY white sharks in their sum- 
mer nursery area in the New York Bight 
(Curtis et al., 2018; Shaw et al., 2021). 
The data presented herein support 
the hypothesis that the area occupied 
by these tracked YOY white sharks rep- 
resents an overwinter nursery area. The 
area meets the shark nursery area cri- 
teria proposed by Heupel et al. (2007): 
our data indicate that YOY white sharks 
occur more frequently in this area than 
in other areas during winter (crite- 
rion 1), they remain in the area for an 
extended period (criterion 2), and they 
use the same area repeatedly across 
years (criterion 3). However, this infor- 
mation is based on only the movements 
of 9 individuals across 2 years, and 
