Sharks come in a variety of shapes and sizes, from the formidable great white, to the tiny cookie cutter, to the massive whale shark, to frankly bizarre oddities like the hammerhead and megamouth. Arguably the most beautiful of all is the blue shark. Slender and sleek, with large, expressive eyes and brilliant, metallic blue skin, these sharks are truly a pleasure to observe. They also have very sharp teeth. Blue sharks are undeniably dangerous to the fish on which they prey, but are they a danger to humans?
What Are Blue Sharks?
Blue sharks (Prionace glauca) are large, pelagic sharks, which inhabit deep, cool water worldwide. They average a little over 3m (9.8ft), but can grow to be some 4m (13ft) long. Their bodies are long and lean, and coloured deep blue on their backs, fading through bright blue on their flanks, to white on their bellies. The blue shark’s snout is distinctly pointed, and its teeth are long and serrated. Female blue sharks are viviparous (give birth to live young), and can give birth to over 100 pups at a time (rather them than me)! And since male sharks have a tendency to bite females during mating, females have skin which is up to 3 times thicker than males (taking thick-skinned feminism to a whole new level). Like other highly migratory species, blue sharks tend to swim slowly in order to conserve energy. However, they are capable of rapid bursts of speed when hunting.
What Do Blue Sharks Eat?
Blue sharks eat squid, octopuses and other cephalopods, as well as a range of fish species and even crustaceans. Blue sharks are also known to scavenge carrion and follow fishing vessels, waiting for bycatch to be thrown overboard. They mostly hunt by simply chasing down their prey, but have sometimes been observed working together in “packs” to herd shoals of fish together and grab those trying to escape.
Where Do Blue Sharks Live?
Blue sharks have a remarkably wide range, and can be found in all of the world’s oceans except the arctic and polar regions. They generally prefer deep, cool waters, but tend to swim within 350m (1150ft) of the surface. In temperate waters, such as around the British Isles, they can be found in the warmer (yet nonetheless frigid) water closer to the shore, where they sometimes come into contact with divers. In tropical regions, blue sharks prefer the cooler water of the deep, so rarely encounter humans.
Blue Shark Attacks On Humans
Since the 1600s, there have only been 23 confirmed unprovoked attacks on humans, most of which resulted in minor injuries. Only 4 attacks were fatal, and bizarrely all of these fatal attacks occurred in the first half of the 20th century. Blue sharks, while among the largest predatory shark species, are popular sharks to swim with.
They are reportedly curious creatures and will investigate divers with interest, sometimes touching them with their nose to better understand what they are. Shark tour agencies often chum the water to attract the sharks, which would be considered risky, even downright dangerous with more aggressive species, because of the feeding behavior it could elicit. Yet, it would seem that blue sharks remain comparatively calm, even in the presence of food. Considering how frequently blue sharks come into contact with swimmers and divers, the number of unprovoked attacks (or in most cases, nibbles) is remarkably small. This may be in part due to the fact that blue sharks tend to prefer smaller, non-mammalian prey, so they probably don’t consider humans to be possible prey. Humans are also decidedly bulky compared to these slim sharks, making them an even less attractive prey item. In truth, the greatest risk in swimming with such beautiful creatures is probably that they will make you feel fat and unattractive.
Are Blue Sharks Dangerous?
Like anything big enough with sharp teeth, large blue sharks have the potential to be dangerous to humans. However, they very rarely ever are, or ever have been. And like literally almost every other animal on earth, humans are far more of a threat to them than they are to us (except mosquitos and cats – mosquitos are everywhere and cats are irresistible bastards). Sadly, blue sharks are frequent victims of fishing, with between 10 and 20 million being killed each year in bycatch alone. They are also intentionally fished for their fins and meat, despite the fact that they reportedly taste unpleasant and are often contaminated with high amounts of mercury and other heavy metals. Blue sharks are also targeted by recreational fishermen, because they apparently “put up a good fight” (why are we like this?!). Despite their being one of the most abundant species of shark, blue shark populations are in heavy decline, perhaps as much as 80% or more in some areas. This is not only a tragedy for the sharks themselves, but could be catastrophic for the entire oceanic ecosystem.
But there is hope! Efforts by conservation organisations such as the IUCN and Shark Trust, as well as conscious decisions by consumers (yes, you and me) to only buy fish from sustainable sources, will help stop the decline of these stunning animals, and give them a chance at a future.