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50. Pelagic Thresher

Alopias pelagicus

About

This species has an extraordinarily long caudal fin it uses a whip to stun its prey, and distinctive prominent eyes. Although it has a circumpolar range, little is known on its biology and ecology.

In order to hunt their prey, pelagic threshers herd schooling fish together and then use their tails to stun them, making the prey easier to catch.

Pelagic threshers only produce two very large (150-190 cm) offspring per litter, making their annual rate of population increase very low (between 2 and 4%). This makes them very vulnerable to population decrease from over fishing. The embryos are oophagous, meaning that they feed on other eggs inside the female. Pelagic threshers can live up to 29 years of age.

The main threat to this species are pelagic fisheries. Along with other thresher sharks, the long caudal fin makes them vulnerable to being caught as bycatch by longline tuna fisheries and they are also caught by some targeted fisheries. Some parts of the threshers such as the skin, liver and their fins are sought after. Although, within the shark fin market, the pelagic thresher’s fins are not highly valued, they are abundant in the Hong Kong fin market. This species is mainly caught on the high seas and so there is very little regulation in place to protect this species. Catches of pelagic threshers are also under reported worldwide, making targeted conservation efforts difficult.

Conservation measures directly targeting this species are not in place, however is affected by other general tools aimed at the management of migratory shark species as well as those addressing illegal and unreported fisheries and shark’s fin trade.

  • Order: Lamniformes
  • Family: Alopiidae
  • Population: Unknown
  • Trend: decreasing
  • Size: Up to 428cm (?)
  • Depth Range (m): Up to 152m

EDGE Score

EDGE Score: 5.52 (?)
ED Score: 61.29 (?)
GE / IUCN Red List (?)
Not Evaluated Data Deficient Least Concern Near Threatened Vulnerable Endangered Critically Endangered Extinct in the Wild Extinct

Distribution

The pelagic thresher is found across the globe in the Indo-Pacific Ocean.

Habitat and Ecology

Not much is known about this epipelagic species ecology. It is a highly migratory species found near the equator in winter but not in summer.

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Download the Survival Blueprint for this species below. Each survival blueprint is compiled by an EDGE Fellow working on the species with input from collaborators and stakeholders. The Survival Blueprint provides a status review (information on the distribution, protection status, habitat & ecology, threat and stakeholder analysis) and more information on the action programme listed here.  

Vision (30-50 years)

Healthy Populations of Pelagic Thresher Sharks in Indonesian waters

Goal (5-10 years)

  • Large commercial shark fisheries are managed to achieve sustainable shark fisheries in Indonesia by 2030
  • Small-scale and artisanal shark fisheries are managed to achieve sustainable shark fisheries in Indonesia by 2030
  • Strengthen the management of domestic and international trade by 2030

Objectives

Priority
Minimise industrial bycatch of pelagic thresher shark by 50%, through development and uptake of mandatory bycatch reduction strategy particularly in purse seine and tuna longline fisheries by 2030 High
Strengthen the implementation of surveillance and monitoring system in all commercial fisheries vessel by 2030 High
Develop mitigation plan, incentive and alternative livelihood scheme to reduce thresher shark catch in small-scale fisheries by 2030 High
Reduce bycatch mortality of pelagic thresher shark by encouraging live release in industrial/commercial fisheries particularly in purse seine and tuna longline fisheries by 2030 Medium
Estimate sustainable quotas for catch and for domestic and international trade by 2030 Medium

Muhammad Ichsan

  • Project name: Pelagic Thresher shark fisheries in Indonesia: characterising industrial by-catch and local-scale targeted fisheries in Aceh
  • Project site: Aceh Province, Indonesia
  • Active: 2019 - ongoing
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