Size and shape
A slim pelagic shark averaging around 3.1 m (10 ft).
Photo byJakob Owens
Species Guide
What to know about blue sharks
A clean field guide focused on habitat, identification, behavior, and conservation context without burying the useful parts.
The blue shark (Prionace glauca) is a requiem shark in the family Carcharhinidae and the only species in the genus Prionace. It inhabits deep waters in the world’s temperate and tropical oceans and prefers cooler waters. Adults average around 3.1 m (10 ft). Blue sharks undertake long-distance migrations (for example, between New England and South America). They are generally lethargic but capable of very quick movement. Blue sharks are viviparous and are noted for very large litters, commonly 25 to over 100 pups. Their diet consists primarily of small fish and squid, though they can take larger prey. Known predators include killer whales and larger sharks such as tiger sharks and great white sharks. They are among the most abundant pelagic sharks, and large numbers are taken as fisheries bycatch on longlines and nets. Fossil teeth attributable to this species are known from Miocene and Pliocene deposits in multiple regions.
Listed as Near Threatened by the IUCN; substantial numbers are removed by fisheries as bycatch on longlines and nets.
Generally lethargic but capable of very quick movement; undertakes long-distance migrations.
Identification
How to identify blue sharks
The visual markers divers can use underwater, plus the species most likely to cause confusion.
Key identification markers
Habitat
Inhabits deep temperate and tropical ocean waters and prefers cooler waters.
Range and Movement
How blue sharks move through the world
The broad range, seasonal movement, or migratory behavior that shapes where divers encounter this species.
Generally lethargic but capable of very quick movement; undertakes long-distance migrations.
Diet
What blue sharks tend to eat
Useful feeding context that often explains habitat, movement, and encounter style.
Feeds primarily on small fish and squid, but can take larger prey.
Population
Estimated numbers and what we actually know
Published estimates when credible, or an explicit note when no reliable global count exists.
Described as one of the most abundant pelagic sharks, though no numeric estimate provided in source.
Conservation
What is happening with Blue Sharks
Status, pressure, and protection context grounded in cited sources rather than filler.
Listed as Near Threatened by the IUCN; substantial numbers are removed by fisheries as bycatch on longlines and nets.
Main threats
Fisheries bycatch
Large numbers are caught as bycatch on longlines and nets, contributing to population pressure.
Responsible Encounters
How to dive with blue sharks
Conservation-minded guidance for divers who want the encounter without adding pressure.
Give blue shark space, avoid blocking the animal's path, and follow local site and operator rules for wildlife interactions with sharks.
Field Notes
Interesting things worth knowing
Useful species context that makes the encounter more meaningful once you are underwater.
Field notes
Only species in its genus
The blue shark is the sole species in the genus Prionace.
Large litters
Blue sharks commonly produce litters of 25 to over 100 pups.
Fossil record
Fossil teeth attributed to this species are known from the Miocene and Pliocene in several regions.
FAQ
Frequently asked questions
Clear planning and conservation answers written for search visibility and AI retrieval.
Research Sources
Blue Shark information sources
Primary and credible references behind the field-guide and conservation claims on this page.
Sources 4Last Updated
Blue Shark – Discover Fishes · Reference · Florida Museum
Primary wildlife guide source.
NOAA Fisheries · Reference · NOAA Fisheries
Supporting wildlife source.
Smithsonian Ocean · Reference · Smithsonian Ocean
Supporting wildlife source.
Blue shark · Encyclopedia · Wikipedia
Supporting wildlife source.
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