Common Thresher Shark

11/20/2018

Thresher shark, Alopias vulpinus, Alex Stoyda

We've mentioned before on The Fins United Initiative that there are three thresher sharks: Long-tailed or Common Thresher Shark (Alopias vulpinus), Bigeye Thresher Shark (Alopias superciliosus), and the Pelagic Thresher Shark (Alopias pelagicus). The Common and Bigeye thresher sharks are thought to occur throughout Dutch-Caribbean waters and has been confirmed in and around the Windward Islands, while the Pelagic Thresher is an Indo-Pacific animal. All three species are listed on the IUCN Red List of Threatened Species as “Vulnerable” because of their declining populations.

The common thresher shark is the largest of the thresher sharks, growing up to 6.1 metres (20 ft) and weigh up to 500 kilogrammes (1,100 pounds). They eat schooling fish such as sardines, mackerel or juvenile tuna. From our General: Thresher Sharks blog post: One of the more recognised sharks thanks to their whip-like tail. Just as deadly as Zorro’s sword, they instead use the elongated upper lobe of their caudal (tail) fin to herd, stun, and ultimately kill their prey (which includes small fish, squids, octopi and sometimes seabirds).

Like many shark species, they are viviparous with placentas, and result in small litters of two to four large, well-developed pups; these pups are known to feed on the mother’s unfertilised eggs, a practice known as oophagy.

WHAT DID YOU LEARN ABOUT THIS ANIMAL?

GLOSSARY

Bycatch: The part of a fishery’s catch that is made up of non-target species.
Commercial fishery: The activity of catching fish and other seafood for profit.
Crustaceans: Group of animals with a hard exoskeleton, jointed legs and segmented body.
Endemic: Native to a specific region or environment and not occurring naturally anywhere else.
Gestation: The period in which a fetus develops, beginning with fertilization and ends at birth.
IUCN: International Union for Conservation of Nature.

Oophagy: Sometimes called "oviphagy;" when developing embryos feed on unfertilized eggs.
Pup: Give birth to baby sharks, skates, rays or chimaeras (pups).
Pups: Baby sharks, skates, rays, or chimaeras.
Trawl fisheries: Fisheries that pull a fishing net through the water behind one or more boats.
Viviparous with yolk-sac: Also known as aplacental viviparous and previously known as ovoviviparous/ovoviviparity; it is the production of eggs that are fertilised and hatch inside the female shark but the embryos lack a placental connection to the oviduct or uterus and so do not feed off the mother.