Pelagic thresher shark

 Alopias pelagicus

Pelagic thresher shark (Alopias pelagicus).

Distribution: Worldwide in temperate and tropical waters. The more tropical pelagic thresher shark generally moves into California waters during periodic warm water episodes relating to El Nino conditions, being more abundant to the south off the Pacific coast of northern Mexico. When it occupies epipelagic habitat within the US West Coast EEZ, it usually does not range north of southern California waters. Associated with sea surface temperatures 21°C and warmer. Neonates and juveniles are not often observed in the Southern California Bight, near the Mexican border.  Large juveniles and adults occur primarily south of Point Conception in warm water years, east of Santa Rosa-Cortes Ridge where water is warmest. Half are adults and half are large juveniles. Females outnumber males 5:1 and 41% of females were found to be pregnant. No discernible difference in distribution among stages. 

Growth and DevelopmentOvoviviparous, about 2 pups/litter born 130-160 cm total length (TL). Sexual maturity is usually reached around 250-300 cm, with maximum reported size around 365 cm TL.

Feeding: Thresher sharks have been observed to use their long caudal fin to bunch up, disorient and stun prey at or near the surface and are often caught on longlines tailhooked.Prey items from California and other waters include anchovy, Pacific sardine, herring, mackerel, Pacific hake, lancetfish, lanternfishes, Pacific salmon, squids, octopus, pelagic red crab, and shrimp. Secondarily, grunion and other atherinids, louvar, white croaker, queenfish, Pacific sanddab and pelagic red crab.

Conservation Status and Management: The pelagic thresher has not be evaluated for conservation status, however, they are subject to bycatch in fisheries worldwide.  

Last modified: 12/8/2015