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Pelagic Thresher Shark

Alopias pelagicus

Description:

The pelagic thresher (Alopias pelagicus) is a species of thresher shark, family Alopiidae; this group of sharks is characterized by the greatly elongated upper lobes of their caudal fins. It is often confused with the common thresher (A. vulpinus), even in professional publications, but can be distinguished by the dark, rather than white, color over the bases of its pectoral fins. The smallest of the three thresher species, the pelagic thresher typically measures 3 m (10 ft) long. The diet of the pelagic thresher consists mainly of small midwater fishes, which are stunned with whip-like strikes of their tails. Along with all other mackerel sharks, the pelagic thresher exhibits ovoviviparity and usually gives birth to litters of two. The developing embryos are oophagous, feeding on unfertilized eggs produced by the mother. The young are born unusually large, up to 43% the length of the mother. Pelagic threshers are valued by commercial fisheries for their meat, skin, liver oil, and fins, and are also pursued by sport fishers. The International Union for Conservation of Nature (IUCN) assessed this species as Vulnerable in 2007.

Habitat:

The pelagic thresher occurs in the tropical and subtropical waters of the Indian and Pacific Oceans, usually far from shore but occasionally entering coastal habitats.

Notes:

The Pelagic Thresher Sharks usually spend their time in deep waters but over in Monad Shoal, Malapascua Island in Philippines, they can be reliably seen in the shallows especially during early morning. Usually at sunrise, they come to the Cleaning Station to be cleaned by Cleaner Fishes/Wrasses. They can also be seen late morning and even in the afternoon but not so reliably. Sometimes, the smaller Sharks will even breach the surface. Practically, all pictures/videos/footages taken of Thresher Sharks at Monad Shoal are without lightings (strobe/torch lights). This practise is accepted by all Dive Operators as the Sharks being from deep waters, have very light sensitive eyes. It is believed the use of lightings will disturb the Sharks and this may cause them to stay away from the Cleaning Station. However, from time to time, there are Divers, including Professional Underwater Photographers who did not follow this guideline.

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3 Comments

AlbertKang
AlbertKang 6 years ago

Thanks, @Sergio and yes, @Marta, I have been to Malapascua Island so many times and each time, am still amazed with the encounters with the Thresher Sharks. You are probably aware that now there are ropes being laid as a marker for Divers not to cross to avoid disturbing the Thresher Sharks when they come for cleaning. And the Thresher Shark, when not disturbed can really come up very close to Divers. Back in 2010, I was staying put at the cleaning station, watching a Thresher Shark that was getting very comfortable with the presence of Divers. It came right up to me and make a turn at the last moment, and hit me on the arm with its left pectoral fin!!! That was an awesome experience :)

Sergio Monteiro
Sergio Monteiro 6 years ago

Great photos and great info. Thank you for sharing this.

The MnMs
The MnMs 6 years ago

I have been there! Awesome experience! :-)

AlbertKang
Spotted by
AlbertKang

Cebu, Philippines

Spotted on Feb 6, 2015
Submitted on Feb 16, 2015

Reference

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