PELAGIC THRESHER SHARK
'Alopias pelagicus'
NAME: Pelagic Thresher Shark
SCIENTIFIC NAME: Alopias pelagicus
STATUS: Endangered
POPULATION DECLINE: The pelagic thresher shark population has plummeted by an estimated 50 - 79% over three generations (approximately 55.5 years), making conservation efforts crucial.
SIZE: At birth: 158 - 190 cm. Mature males: 267 - 347 cm. Mature females: 280 - 428 cm
DISTRIBUTION: These sharks inhabit tropical to temperate waters across the Pacific and Indian Oceans.
HABITAT: True ocean wanderers, pelagic threshers are usually found offshore in waters up to 300m deep. They’re often spotted near drop-offs, narrow continental shelves, and seamounts, so divers, keep an eye out when exploring these hotspots
DIET: Pelagic threshers feed on small fish and cephalopods, using their incredible tail to help catch their prey.
BEHAVIOUR: While much about their behaviour remains a mystery, pelagic threshers are known to be strong swimmers and highly migratory. Lucky observers might catch them breaching repeatedly, thought to be their way of shaking off pesky parasites. They are shy around divers and are harmless to humans.
BIOLOGY:
- Litter size: 2 pups (one from each uterus), nourished on unfertilised eggs.
- No seasonal breeding cycle; pregnant females with embryos in various stages of development are seen year-round.
- Males reach maturity at 7 - 8 years, females at 8 - 13 years.
- Lifespan: Males live up to 20 years; females can reach 29 years.
THREATS: These sharks face numerous threats, including overfishing for their meat, liver oil, skins, and fins. They’re often caught on longlines targeting tuna and marlin, as well as in bycatch. Sadly, they are also a popular target for sport fishers due to their distinctive tails.
FUN FACTS
- Wip-like tails: Thresher sharks have tails as long as their bodies. They whip these tails at speeds of up to 80 mph to stun fish and squid, making hunting a breeze.
- Built-in heater: They’re regional endotherms, meaning they can keep their bodies warmer than the surrounding water, perfect for their fast-paced lifestyle.
- Speedy swimmers: Pelagic threshers can swim up to 22 mph, making them one of the ocean’s fastest predators!
REFERENCES
- “Pyjama Shark.” Shark Guardian, https://www.sharkguardian.org/post/pelagic-thresher-shark.
- “The IUCN Red List of Threatened Species.” IUCN Red List of Threatened Species, www.iucnredlist.org/.
- David A. Ebert. et al, 2021, Sharks of the World: A Complete Guide.