Pelagic Thresher
Also known as: Alopias pelagicus (scientific name) · Pelagic fox shark · Smalltooth thresher
Definition
The pelagic thresher (Alopias pelagicus) is a slender shark distinguished by a whip-like upper tail fin as long as its body, found across the Indo-Pacific and made famous in the Philippines by Monad Shoal off Malapascua Island, Cebu, the only place in the world where these shy, oceanic sharks reliably gather at cleaning stations reachable by recreational divers. Heavily fished for its meat and fins across Asia, it is classified as Endangered, and the Malapascua dive economy has become a celebrated case of a shark being worth more alive than caught. (Wikipedia)
Identities
| Source Type | Identity |
|---|---|
| Wikipedia | Pelagic thresher |
| Wikidata | Q1274522 |
| DBpedia | N/A |
| ProductOntology | N/A |
| Wiktionary | N/A |
| Library of Congress Subject Headings (LCSH) | Sharks |
| MeSH | N/A |
| NCBI Taxonomy | Alopias pelagicus |
| AGROVOC | sharks |
| Google Scholar | Alopias pelagicus pelagic thresher Malapascua Monad Shoal conservation endangered fishery Philippines |
| ConceptNet | shark |
| OpenCyc | N/A |
Also Known As
- Alopias pelagicus (scientific name)
- Pelagic fox shark
- Smalltooth thresher
Examples and Analogies
- Tail as a Whip: It stuns schooling fish with slaps of its elongated tail, the only shark group known to use the caudal fin as a weapon this way.
- Alarm Clock Diver’s Shark: Dawn dives at Monad Shoal are timed like a train schedule, because the sharks visit cleaning stations most reliably in early-morning light.
Usage Scenarios
1. Shark Diving Tourism
Malapascua’s dive shops run daily dawn trips to Monad Shoal, sustaining much of the island’s economy.
2. Conservation Campaigns
The species anchors anti-finning advocacy in the Visayas, demonstrating how protected dive sites reduce local catch pressure.
Strategies
- Enforce no-fishing rules and mooring discipline at Monad Shoal and nearby seamounts to protect cleaning-station behavior.
- Pair tourism revenue with community fisheries support so islanders benefit directly from live sharks.
Security and Safety Measures
- Divers observe from the reef ledge without chasing or touching sharks, keeping the animals’ natural behavior intact.
- Dive operators follow deep-site safety protocols, including no-decompression limits and strong-current procedures.
Historical Context
The species was described from Indonesian waters in the mid-twentieth century after decades of confusion with the common thresher, and Filipino divers in the 1990s discovered that threshers rose each dawn over Monad Shoal, a submerged seamount north of Malapascua. As word spread, the island transformed from a fishing community into an international shark-diving hub, and the shark’s Endangered listing in 2016 intensified calls to safeguard the shoal, leading to local marine protections and research on the population’s movements. (Wikipedia)
Challenges and Controversies
Targeted and Bycatch Fishing
Outside protected waters, threshers are caught in longlines and gillnets for fins and meat, driving global decline.
Tourism Carrying Capacity
Growing diver numbers at Monad Shoal raise concerns about anchor damage, crowding, and disturbance to shark behavior.