Document
Endangered Species Act Status Review of Common Thresher (Alopias vulpinus) and Bigeye Thresher (Alopias superciliosus) Sharks
The 2016 status review report conducted on two petitions to list the common and bigeye thresher…
Atlantic Common Thresher Shark
Atlantic Common Thresher Shark
Alopias vulpinus
Also Known As
Thresher shark, Fox shark, Sea fox, Swingletail, Whiptail shark, Thintail shark
Quick Facts
Location
New England/Mid-Atlantic,
Southeast
About the Species
U.S. wild-caught Atlantic common thresher shark is a smart seafood choice because it is sustainably managed and responsibly harvested under U.S. regulations.
Population Level
The stock has never been assessed. The population level is unknown, but presumed stable.
Fishing Status
At recommended level.
Habitat Impacts
Gear used to harvest Atlantic common thresher shark does not contact the ocean floor and has no impact on habitat.
Bycatch
Bycatch is low because Atlantic common thresher sharks are primarily incidental catch in other fisheries.
Status
- Atlantic common thresher sharks have never been assessed and the population status is unknown. The fishing rate has been kept at the recommended level.
- The International Commission for the Conservation of Atlantic Tunas conducted an ecological risk assessment for pelagic sharks caught in Atlantic pelagic longline fisheries and ranked thresher sharks as the least vulnerable to these fisheries and more productive than the other species included in the risk assessment.
Appearance
- Thresher sharks are brown, gray, blue-gray, or blackish on the back and underside of their snout.
- They are lighter on the sides, and fully white below.
- Their pectoral, pelvic, and dorsal fins are blackish, and there are sometimes white dots on the tips of the pectoral, pelvic, and tail fins.
- Their tail fin is sickle-shaped, and the upper part is extremely long, about half the length of their body.
Biology
- Common thresher sharks live a long time (19 to 50 years), reproduce late in life, and have only a few young at a time.
- They grow slowly, but can reach up to 20 feet long.
- Males sexually mature when they’re 8 to 11 feet long and 3 to 6 years old. Females are able to reproduce when they’re 8 to 9 feet long and 4 to 5 years of age.
- Common thresher sharks mate in late summer. Eggs are fertilized internally and develop within the mother. Females bear live, fully developed young after a long gestation period (9 months), and only have a few pups.
- Common thresher sharks are aggressive predators that feed near the top of the food chain on schooling fish such as herring and mackerel and occasionally on squid and seabirds.
- They are named for their long, scythe-like tail, which is used to stun fish before preying on them.
- Adult common thresher sharks have few predators, but younger, smaller ones may fall prey to larger sharks.
Where They Live
- Common thresher sharks are found in temperate waters around the world.
- In the northwest Atlantic Ocean, they range from Newfoundland to Cuba.
Management
- NOAA Fisheries and the Atlantic Highly Migratory Species Division manage the Atlantic common thresher shark fishery in the United States.
- Managed under the Consolidated Atlantic Highly Migratory Species Fishery Management Plan:
- Permits are required, and only a limited number of permits are available.
- Commercial quotas and limits on how many sharks can be landed per fishing trip.
- Gear restrictions and requirements.
- Fishing season is generally year-round, but individual commercial shark fisheries close when the quota is reached.
- Shark dealers are required to attend Atlantic shark identification workshops to help them better identify shark species.
- Prohibited species—there are more than 20 species of sharks that cannot be landed (e.g., white, dusky, basking, longfin mako, night). Some of these species look similar to the species that can be landed. The recreational shark identification and the prohibited shark identification placards can help with identification.
- The Shark Conservation Act requires that all sharks, with one exception, be brought to shore with their fins naturally attached.
- Compliance guides are available for all commercial and recreational regulations across Atlantic highly migratory species fisheries.
- Highly migratory species, such as thresher sharks, have complicated management that requires international cooperation.
- A shark that is off the coast of Florida one week could be caught off the coast of Mexico the next. These resources must be managed both in the United States and at the international level.
- The United States negotiates with Regional Fisheries Management Organizations—including the International Commission for the Conservation of Atlantic Tunas, the Food and Agriculture Organization of the United Nations, and the Convention on International Trade in Endangered Species of Wild Fauna and Flora to enhance shark management worldwide.