399 
National Marine 
Fisheries Service 
NOAA 
Fishery Bulletin 
e established in 1881 << 
Spencer F. Baird 
First U.S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Abstract—Improved understanding of 
the seasonal distribution, habitat use, 
and fishery interactions of the common 
thresher shark (Alopias vulpinus) in the 
western North Atlantic Ocean (WNA) is 
required for future management. We 
compiled and analyzed 3478 fishery- 
dependent capture records in the WNA 
between 1964 and 2019 to examine 
dynamics by sex and life stage (i.e., 
young of the year, juvenile, and adult). 
Sharks were captured over a broad geo- 
graphic range from the Gulf of Mexico to 
the Grand Banks, primarily in continen- 
tal shelf waters shallower than 200 m. 
Seasonal north-south movements along 
the east coasts of the United States 
and Canada were observed for all life 
stages and both sexes, with individu- 
als generally occurring at more north- 
erly latitudes in the summer and more 
southerly latitudes in the winter. Dis- 
tinct areas of more frequent capture 
in fisheries were identified for all life 
stages throughout their range. Com- 
mon thresher sharks were observed in 
waters with sea-surface temperatures 
of 4-31°C, most commonly of 12—18°C. 
The results of this study will help to 
identify essential fish habitat for each 
life stage of common thresher sharks 
along the U.S east coast and to develop 
management measures for the WNA 
population. 
Manuscript submitted 22 June 2020. 
Manuscript accepted 15 December 2020. 
Fish. Bull. 118:399-412 (2020). 
Online publication date: 31 December 2020. 
doi: 10.7755/FB.118.4.8 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Seasonal distribution and habitat use of the 
common thresher shark (A/lopias vulpinus) in 
the western North Atlantic Ocean inferred 
from fishery-dependent data 
Jeff Kneebone (contact author)! 
Heather Bowlby” 
Joseph J. Mello? 
Camilla T. McCandless* 
Lisa J. Natanson* 
Brian Gervelis” 
Gregory B. Skomal® 
Nancy Kohler’ 
Diego Bernal’ 
Email address for contact author: jkneebone@neaq.org 
" Anderson Cabot Center for Ocean Life 
New England Aquarium 
1 Central Wharf 
Boston, Massachusetts 02110 
? Bedford Institute of Oceanography 
Fisheries and Oceans Canada 
1 Challenger Drive 
P.O. Box 1006 
Dartmouth, Nova Scotia B2Y 4A2, Canada 
3 Northeast Fisheries Science Center 
National Marine Fisheries Service, NOAA 
166 Water Street 
Woods Hole, Massachusetts 02543 
4 Northeast Fisheries Science Center 
National Marine Fisheries Service, NOAA 
28 Tarzwell Drive 
Narragansett, Rhode Island 02882 
The common thresher shark (Alopias 
vulpinus) is one of 2 species in the fam- 
ily Alopiidae that occurs in temperate 
and subtropical regions of the North 
Atlantic Ocean (Compagno, 2001). 
In the western North Atlantic Ocean 
(WNA), common thresher sharks are 
thought to represent a discrete popu- 
lation (Castro, 2011; Rigby et al., 2019) 
and occur from Cuba to Newfoundland, 
Canada (Compagno, 2001). There is 
currently no large-scale, directed com- 
mercial fishery for this species in the 
WNA, but common thresher sharks 
are often caught incidentally in pelagic 
longline and demersal gill-net fisheries 
and occasionally are retained for sale in 
> Integrated Statistics for Northeast Fisheries 
Science Center 
National Marine Fisheries Service, NOAA 
16 Sumner Street 
Woods Hole, Massachusetts 02543 
© New Bedford Office 
Massachusetts Division of Marine Fisheries 
836 South Rodney French Boulevard 
New Bedford, Massachusetts 02744 
7 University of Massachusetts Dartmouth 
285 Old Westport Road 
Dartmouth, Massachusetts 02747 
the United States (NMFS, 2019a). The 
common thresher shark is also the tar- 
get of an extensive recreational shark 
fishery from Virginia to Maine with 
the majority of sharks landed (NMFS, 
2019a) because their flesh is considered 
excellent (Compagno, 2001). 
There is limited and conflicting 
information on the status of the pop- 
ulation of common thresher sharks in 
the WNA. Results of studies examining 
pelagic longline logbook data collected 
since the late 1980s for thresher sharks 
(i.e., the common thresher shark and 
the bigeye thresher, A. superciliosus, 
combined) indicate that their relative 
abundance has declined by 63-80% 
