Pelagic Thresher

The Pelagic Thresher is a large shark distinguished by an extraordinarily elongated upper caudal fin lobe, which can equal the length of the rest of its body. This adaptation is used as a hunting tool, allowing the shark to stun schooling fish and squid by whipping its tail through the water at high speed. Slender-bodied and typically dark blue-grey to brownish above with a paler underside, this species is a highly migratory, active predator occupying the upper layers of the open ocean, occasionally venturing into coastal waters.

It plays an important role in regulating populations of small schooling fish in pelagic ecosystems.

The species has a wide distribution across tropical and warm-temperate waters of the Indian and Pacific Oceans, with confirmed presence in the coastal and offshore waters of over 30 countries, including the Philippines, Indonesia, Taiwan, Mexico, and Australia. It inhabits marine oceanic environments, generally favoring areas near seamounts, offshore islands, and productive continental shelf edges.

The primary threat to the Pelagic Thresher is fishing, both targeted and incidental. Its long fins are highly valued in the international shark fin trade, and its low reproductive rate—typically producing only two pups per litter—limits population recovery. It is caught in longline and gillnet fisheries throughout its range, often as bycatch in tuna fisheries.

Conservation measures include listings under CITES Appendix II, which regulates international trade in thresher shark products, and regional fishing restrictions or finning bans in some countries. Enforcement remains inconsistent across much of its range. With continued fishing pressure and slow reproduction, the population is assessed as decreasing, and the species remains at significant risk of further decline without stronger, consistently enforced management.