Common Thresher Shark

About the Common Thresher Shark

The common thresher shark, also known as the fox shark or swiveltail, is the largest member of the thresher family. It can be found in tropical, temperate and cold-temperate waters from the surface to depths of 650 m (2,132 ft). Its range includes the Atlantic, Pacific, and Indian Oceans, as well as the Mediterranean and Black Seas.

Biology and Behaviour

Adults are on average about 4.5 m (14.8 ft) long, and the species can reach approximately 5.7 m (18.7 ft), with possible records of up to 6.3 m (20.7 ft) and a maximum weight of 510 kg (1,124 lb). Their most distinctive feature is their very long upper tail lobe, which can reach up to 3 m (9.8 ft)  in length and represent half of the shark’s total body length. This enormous tail is used as a whip to stun prey, such as herrings, mackerel and anchovies. To do this, they find a school of fish, swim around it to compress it and then strike quickly, often stunning several fish simultaneously.

In addition to its tail, the common thresher has several adaptations that make it a fierce predator. It is a fast swimmer and powerful enough to leap out of the water. It can also generate and maintain body heat better than most other sharks. And it has about 50 rows of teeth, with sharp, triangular teeth ideal for catching small prey.

The common thresher is very similar to the pelagic thresher (Alopias pelagicus), but the two can be distinguished by the common thresher’s white belly, which extends in a band over the bases of its pectoral fins.

Reproduction and Lifespan

Common threshers are ovoviviparous, meaning that embryos develop inside eggs that hatch within the female’s uterus. Each litter contains between 2 and 6 pups, and reproduction is annual or biennial. Pups measure approximately 120 to 150 cm (47.2–59.1 in) at birth. Females mature at around 13 years of age, and the species can live for up to 38 years.

Conservation

Common threshers are caught both as bycatch and intentionally for their meat and fins. They are assessed as vulnerable by the IUCN due to overfishing and their slow reproductive rates. They are listed in CITES appendix II, which means that international trade requires a permit. The species is protected in some regions, such as California, but internationally, they are not managed and there are no quotas.

Do you have images or videos of Common Thresher Sharks?
Submit them to [email protected].

Common Thresher Shark Gallery