Blue Shark | Oceana Canada

Canadian Marine Life Encyclopedia

Blue Shark

Prionace glauca

Also known as

Blue dogs, blue pointers, great blue sharks

Distribution

Global oceans; tropical to cold temperate

Écosystèmes/habitats

Pelagic/open ocean

Feeding Habits

Active predator

Conservation Status

Special concern/data deficient

Taxonomie

Order Carcharhiniformes (ground sharks), Family Carcharhinidae (requiem sharks)

Partager

Facebook Twitter Pinterest Google+

Blue sharks get their name from their beautiful blue colour. They have distinct indigo blue on their backs, vibrant sapphire blue along their sides and white underbellies. This species is one of the most widespread and easily recognizable sharks. Because of their inquisitive nature and need to gently investigate everything and anything that crosses their path, they have earned the nickname “blue dogs” or “puppies of the sea.” 

Blue sharks are long, slender sharks found in the open ocean. On average, they reach two to three meters long, although they can grow to four metres. They have a unique colour, which helps to distinguish them from other sharks. Blue sharks are a highly visually oriented predator, which is why they have large eyes, compared to the size of their head, and a long pointed snout. Their slender tapered body and long pointed pectoral fins allow them to swim quickly and glide along ocean currents. 

Blue sharks spend most of their lives in groups based on sex, with males and females living in different areas until they migrate to breed and feed on congregations of prey species. Adults become sexually mature when they reach two to three meters long, which typically occurs around four to six years of age. 

After breeding, the female will go through a gestation period of nine to twelve months. They give birth to litters that range in size from 25 to 50 pups. The number of pups a female can give birth to depends on her size, with larger older females having more pups than smaller, younger ones. Blue sharks feed mainly on schooling fish, such as herring, hakes and squid, but they are also known to feed on carcasses of whales, other marine mammals and sea turtles. 

Blue sharks are targeted worldwide by shark fisheries for fins and meat; however these directed commercial fisheries do not exist in Canada. Since shark finning was banned in Canada in 1994, there have been no sharks targeted and killed for this purpose; however they are targeted by a catch-and-release recreational fishery, shark derbies in Nova Scotia, and are frequently caught as bycatch (incidental catch) in Atlantic Canada’s longline fisheries for tuna and swordfish. 

Due to similar lifestyle and movement patterns as swordfish and tuna, blue sharks interact with these fisheries and are attracted to the bait set out on the longlines. Sharks can be fatally injured by the hooks, become entangled in the line while trying to free themselves, and attacked by larger predatory sharks because they are vulnerable when they on a hook. 

A few hundred to a few thousand blue sharks are caught incidentally on pelagic longlines in Canada every year. Blue sharks are the most common species caught as bycatch in most regions of the world. For those sharks caught on a pelagic longline, there is a fairly high post-release survival rate.

In 2006, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) listed blue sharks found in Atlantic Canadian waters as Special Concern, and those found in Pacific Canadian waters as Data Deficient. They are a widespread and fairly productive shark, allowing them to recover relatively easy from population declines compared to some other shark species. There is some evidence indicating blue shark populations are declining in Atlantic Canada and more research is needed to access Pacific coast populations. 

Oceana Canada is working to protect Canada’s oceans for species like the blue shark. Find out more about our campaigns and join us in helping to bring abundance back to the ocean.