70 
Fishery Bulletin 120(1) 
from data from the NOAA Visible Infrared Imaging 
Radiometer Suite at a spatial resolution of 4.17 km (avail- 
able from website). Daily SSH data were collected from 
the Naval Oceanographic Office Hybrid Coordinate Ocean 
Model and Navy Coupled Ocean Data Assimilation at a 
spatial resolution of 1/12° (available from website). Values 
for oceanographic characteristics were matched to daily 
shark positions by using the xtractomatic function in R, 
vers. 3.6.0 (R Core Team, 2019). 
All location and environmental data were visualized 
by using ArcMap 10.7 (Esri). The overwinter cumulative 
activity space (i.e., home range) for the tracked sharks 
was characterized by using a minimum convex polygon. 
By using ArcMap, the resulting minimum convex polygon 
was compared to spatial management areas for highly 
migratory species, including to the boundaries of the cur- 
rent EFH for YOY white sharks (Federal Register, 2017) 
and to the Mid-Atlantic Shark Closure Area—an area 
off North Carolina that is closed to shark bottom long- 
line fishing from 1 January through 31 July each year to 
reduce fishing mortality on overfished dusky (Carcharhi- 
nus obscurus) and sandbar (C. plumbeus) sharks (NMFS}). 
Results 
Twenty YOY white sharks were tagged near Montauk, 
New York, in August 2016 (number of samples [n]=9) 
and August 2017 (n=11). For 9 of those sharks, 1111 tag 
detections were recorded in their first overwinter period 
(2016: n=4; 2017: n=5) (Table 1). Analysis of habitat use 
was based on a total of 184 daily positions, including 19 
detections from 16 acoustic receivers at unique locations 
in the MATOS network, 76 positions transmitted to Argos 
satellites, and 89 positions interpolated between tag 
detections. During both years, sharks occupied a similar 
distribution, mostly in continental shelf waters off the 
coasts of North and South Carolina (32—37°N) (Fig. 1A). 
The sharks traveled along the coastline mostly over depths 
<100 m, although a few excursions were made beyond 
the continental shelf break over bottom depths >2000 m. 
The mean depth associated with tag positions was 74 m 
(standard deviation [SD] 329) when these extreme depths 
are included. However, 92% of all positions occurred over 
depths <80 m. 
The YOY white sharks were exposed to similar ranges 
of oceanographic conditions in their overwinter habitat. 
The SSTs ranged from 12.9°C to 23.4°C with a mean of 
18.4°C (SD 2.5). The majority of observations (60%) fell 
within a range of 16.0—21.0°C. Despite their proximity to 
the Gulf Stream, the tagged sharks generally were not 
located in its warmer waters (Fig. 1A). The YOY sharks 
occurred in waters with a mean SSH of -0.5 m (SD 0.2) 
and rarely occurred in areas with positive SSH (e.g., the 
Gulf Stream) or in areas with SSH less than —0.9 m. Addi- 
tionally, the sharks used somewhat productive areas with 
Table 1 
Descriptions of 9 young-of-the-year white sharks (Carcharodon carcharias) tracked in the Northwest Atlantic 
Ocean during winter months (December—April) between 2016 and 2018, as well as of their tracking and 
detected positions and of characteristics of the habitat they used. Mean and range of sea-surface temperature 
(SST), depth (bathymetry), chlorophyll-a (Chl-a) concentration, and sea-surface height (SSH) are provided 
with standard deviations in parentheses. Shark IDs correspond to the individual sharks described in Shaw 
et al. (2021). 
Total 
Shark length 
ID (cm) 
Tracking 
Sex period 
WS1 142 
29-Jan-2017 
17-Jan-2017 
WS2 158 
WS7 162 10-Mar-2017 
WS8 162 4-Dec-2016 to 
20-Apr-2017 
22-Dec-2017 to 
5-Mar-2018 
5-Dec-2017 to 
8-Mar-2018 
2-Dec-2017 to 
2-Apr-2018 
5-Dec-2017 to 
1-Apr-2018 
2-Feb-2018 to 
16-Feb-2018 
WS9 150 
WS11 166 
WS13 147 
WS16 154 
WS17 152 
No. daily 
positions 
8-Dec-2016 to 13 
1 
Chl-a 
(mg/m*) 
Depth 
SST (°C) (m) SSH (m) 
15.3 (0.9) 90 (89) 0.7 (0.6) 
14-16.5 14-339 0.3-2.3 —0.7-0.5 
20.4 27 1.0 —0.6 
17.9 39 1.2 -0.7 
18.6 (2.0) 30 (5.5) 1.3 (0.7) -0.6 (0.1) 
13.5-21.7 18-41 0.6—-3.2 —0.9-0.4 
19.5 (2) 45 (57) 0.7(0.6)  —0.5 (0.1) 
14.6—22.8 7-342 0.3-3.2 —0.9-0.2 
18.6 (2.3) 124 (527) 0.8(0.9)  —-0.5 (0.2) 
12.9-23.4 1-3283 0.2-6.1 —0.8-0.1 
14.9 (1.3) 13 (4) 1.8(0.6)  —-0.4 (0.2) 
13.5-17.1 6—20 0.8-2.7 -—1.0-0.1 
16.4 (1.0) 9 (5) 2.8(1.3) -0.4 (0.2) 
15.5-17.8 5-14 1.44.0 -—0.7-0.1 
21.2 (0.6) 57 (30) 0.4(0.1) -0.6 (0.1) 
19.4-22.0 27-134 0.3-0.7 —0.7-0.5 
-0.6 (0.1) 
