Pelagic Thresher Shark

Overview

The pelagic thresher is the smallest of the three thresher sharks. Like its relatives, it is known for a very long, whip-like upper tail lobe. It lives in tropical and subtropical waters of the Indian and Pacific Oceans. It is listed as Endangered by the IUCN, mainly because of fishing pressure.

Distribution & habitat

This is mainly an open-ocean shark that usually stays far from shore. It sometimes comes inshore and may enter atoll lagoons. Divers have reported it near coral reefs, drop-offs and seamounts. In a few places, such as Malapascua in the Philippines, it visits cleaning stations where small fish clean its skin. Sightings elsewhere are mostly random and often distant.

Appearance

The body is torpedo-shaped, with long, straight pectoral fins that have broad, rounded tips. The upper tail lobe is nearly as long as the rest of the body. It is dark grey to bronze above and white below. A dark patch over the pectoral fin bases separates it from the similar common thresher, which has a white patch there.

Feeding

It eats mainly small midwater fish, and probably squid as well. It stuns prey with whip-like strikes of its tail.

Reproduction

Pups develop inside the mother and are born live, usually two per litter. After the yolk sac is used up, the embryos feed on unfertilised eggs the mother produces. Pups are born large, at roughly 130–160 cm. Females mature late, at around 9–13 years in studied populations, and there is no set breeding season. Together with heavy longline fishing, this slow reproduction makes populations slow to recover.