Thresher Shark - Alopias vulpinus

Status: Vulnerable … Thresher Shark stun their prey with a thrash of their long tails

Type: Fish (Alopiidai)

Location: Found throughout the world’s oceans, in both tropical and cold-temperate seas.

Size: Approx 6m in length, including tail fin.

Habitat: Coastal and oceanic waters, ranging from the surface to over 350 metres depth.

Main Threats:
Thresher sharks are threatened from unmanaged and unreported fishing and bycatch fisheries. The meat is highly prized fresh for human consumption and is also eaten smoked and dried salted. The fins are valuable for shark-fin soup, the hide is useable for leather and the liver oil can be processed for vitamins. They are particularly vulnerable to even moderate levels of exploitation because they don’t reach sexual maturity until 8-13 years old.

Many countries fish for thresher sharks commercially throughout their extensive ranges. They are often caught by offshore longline and pelagic gillnet fisheries, as well as being fished with anchored bottom and surface gillnets. They are also caught as bycatch of other gear including bottom trawls and fish traps. They are also an important sport fishery resource, the meat is considered excellent for consumption, and the large fins are highly valued. The growing and largely unregulated shark fin trade also represents a serious threat to thresher sharks.

The adoption of shark finning bans by governing bodies around the world is accelerating and should increasingly prevent the fishing of thresher sharks for their fins alone. Thresher sharks are a designated prohibited species under EU law, which means that the deliberate targeting of thresher sharks in the Atlantic and Indian Oceans by EU and third party vessels is prohibited, although retention of thresher sharks caught as bycatch is allowed in the Atlantic.

Thresher sharks are viviparous, meaning they bear live young that have developed inside the mother’s body. However, unlike in humans, the young is not fed through an umbilical cord but with the egg yolk surrounding the young. Mating occurs in mid-late summer. Thresher sharks are pregnant for nine months, then give birth to 3 to 7 young in spring. They prey on small bait fish including anchovies, herring, mackerel, lancetfish, lanternfish, as well as salmon, squid, octopus, crabs and shrimp.

Did you know?

• The unusually long tail, which gives the shark its name, can be as long as the shark’s body and is used for hunting. The sharks herd prey fish into tight shoals, and then rapidly swim at the shoals thrashing with their long tails to stun some of the fish, which are then quickly captured and eaten.
• They have small mouths with over 80 very sharp teeth, but are no threat to humans.
• They are strong, fast swimmers and, if provoked, can leap clear out of water, a behaviour that makes them much sought after by sport anglers.
• Thresher sharks are endothermic, which means they can generate and maintain a higher internal body temperature than that of their surroundings. This is why they thrive in both warm and colder waters.

What MCS is doing:

• Working towards better protection of important marine habitats in the UK;
• Campaigning at EU level for more effective regulation of fisheries that can impact thresher sharks.