American Oceans
blue shark

Blue Shark

When you think of a shark, you probably immediately think of a Great White Shark launching out of the water to feast on a seal. However, one of the most common sharks in the world is the blue shark. 

While it’s not as ferocious or large as the notorious Great White, the blue shark stuns with its slender body and rich indigo coloring for which it gets the name. Not to mention, it’s considered one of the more docile shark species out there. Keep reading to learn more about this blue beauty.

Characteristics and Appearance

The blue shark gets its name from its vibrant blue appearance, but it differentiates itself from the other shark species in its general size and other distinguishing physical characteristics.   

Weight and Length

The blue shark has a slender, elongated body that measures between six and seven feet from tip to tail for average matured males while matured females measure a few centimeters longer. Given the disparity in length between males and females, the blue shark differs slightly concerning weight but still averages about 250 pounds when fully grown. 

Physical Characteristics and Color

Just as the blue shark’s body is lengthy, its pectoral fins are as well with pointed tips. Its snout is rounded, set between two large eyes, and equally as slim as its body but broader than its mouth. The shark’s dorsal fin is around the average size considering the shark’s overall size compared to other species. Still, it is distinctive because it resides closer to the pelvic fins than to the pectoral fins.  

The shark’s color is evident because of the name; it’s blue. However, that distinctive color fades as it curves around the body resulting in a stark white underbelly. This coloring and contrast allow the blue shark to camouflage quickly and easily in the open ocean.     

Lifespan and Reproduction

While blue sharks are migratory creatures, they settle for a short period to mate in shallower water than they typically stick to. The female blue shark will carry the embryo for 9-12 months before giving birth. 

They also differ from other sea animals in that they, much like humans, carry and nourish the embryo until it’s grown, whereas other sea-life lays eggs and remains with them until they hatch. The female can produce a litter of anywhere between 30 and 80 pups during a single reproduction cycle.   

Male blue sharks mature between ages four and six, while females mature later between ages five and seven. The average lifespan for a blue shark is around 20 years, but some may last even longer. 

Habitat

The blue shark is a migratory aquatic predator, meaning it doesn’t remain in one specific location during its lifetime. Instead, the predator travels across the world in deeper waters. Either cool or tropical, the blue shark does not have a preference though they typically seek milder waters in temperatures between 45 and 75 degrees Fahrenheit.

As pelagic predators, the blue shark resides in waters farther from the coast in deep waters where the temperature is favorable to its preference.   

Where Do Blue Sharks Live?

Since the blue shark is migratory, it does not live in a specific region instead of in a range of areas where the water temperature is suitable and the food is plentiful. They have lived in places as Southern as Chile and as Northern as Norway. 

Food and Diet

Since sharks are at the top of the marine-life food chain, you’d think the blue shark could and would eat just about anything it wanted. However, the blue shark isn’t a wild, blood-thirsty beast. Instead, the blue shark typically eats a healthy diet of fish, squid, and the occasional seal.  

What Do Blue Sharks Eat?

As a deep-sea creature, the blue shark’s diet consists of pelagic fish such as cod, pollock, herring, butterfish, tuna, swordfish, and a few other specific species of larger deep-water fish. Although, the blue shark favors eating squid. Even though sharks are considerably large, the blue shark eats smaller organisms such as shrimp, lobster, and seabirds.  

When they inhabit or migrate through areas shared with seals, blue sharks will chow down on a seal or two if they want, but they don’t dominate the shark’s diet. Blue 

Because of their impressive ability to sense blood in the water, blue sharks will, from time-to-time, feast on the leftovers of dead whales and porpoises. Since they’re also opportunistic creatures, the blue shark is known to snag fish from fishing lines.  

Threats and Predators

People don’t often think of sharks as vulnerable to predators and threats because they are apex predators themselves. However, there are quite a few factors that threaten the blue sharks’ existence both within the food chain and as a byproduct of human error.  

Human Threats

While humans don’t specifically target and hunt blue sharks, the species remains one of the most heavily fished as a bycatching product. Millions of blue sharks each year become victims of bycatching because of the extensive fishing market and overfishing. Some will get returned to the ocean, but most will die from their capture or fin removal. 

Humans don’t typically fish for sharks for the quality of their meat but their fins. Since shark fins hold value, people will fish for sharks, remove their fins, toss the bodies into the ocean and turn around to sell the fin for a high price. 

Some people search for the blue shark precisely because of its vibrant, royal color. People use the fins for everything from decorative home pieces and souvenirs to shark fin soup. Either way, it’s a horrendous act that leaves many shark species endangered. 

Climate Change and Global Warming

The blue shark can survive in a wide scale of water temperatures, but they prefer and have a physiological need for water with a higher oxygen concentration. Studies have found that the blue shark will not dive into depths with a low-oxygen concentration. 

Since climate change is adversely affecting the ocean’s oxygen levels, this could mean the blue shark will take to shallower areas with a higher percentage. Ultimately, the lack of oxygen-rich water will drive blue sharks to shallower depths, making them vulnerable to fishing since those areas traffic that primary industry. 

Predators

Since blue sharks, like most sharks, reside at the top of the marine-life food chain, they have relatively few predators, including Orca Whales and a couple of other larger shark species such as the Shortfin Mako and the White Shark. 

Other Threats

While not as ferocious or deadly as the larger predators like the Orca, parasites are also a form of predator to the blue shark. Sharks unknowingly consume parasites, specifically copepods and nematodes, from the food they consume. 

The specimen, while minuscule and unlikely to cause death unless in extreme abundance, causes irritation and discomfort to the blue shark’s skin, gills, and stomach.  

Conservation Status

According to the International Union for the Conservation of Nature (IUCN), the blue shark is considered “near endangered.” The shark’s near endangered status means that it is currently not critically threatened or endangered to go extinct but can potentially be soon. 

If overfishing and climate change continue as is, the likelihood of the blue shark becoming critically endangered increases. While a “near dangered” status is not as severe as full-blown endangered, the world needs to treat it as such otherwise, the blue shark will end up in that category or worse. 

Fun Facts About Blue Sharks

  • Blue Sharks don’t typically swim their long journeys alone. Instead, the species forms groups or packs based on gender and size. Within these packs, the blue sharks fall in line with a hierarchy and tend to display aggressive behaviors, hence the nickname “wolves of the sea.”
  • Since the late 1500s, there have only been 13 recorded Blue Shark attacks on humans.
  • The blue shark has a bizarre yet captivating mating ritual in which the male repeatedly bites the female. As a result, female blue sharks have evolved to have an extra thick layer of skin.
  • Since blue sharks are highly migratory, the IUCN has reported them as native to the waters of 150 countries.

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