Threats to Sharks
Sharks have inhabited Earth’s oceans for 400 million years, but today they are disappearing at an alarming rate. Because they are very slow to reach reproductive age—anywhere from 12-15 years—and typically only give birth to one or two pups at a time, sharks have great difficulty recovering their populations after extreme depletions. Of the 465 assessed species of sharks living in our oceans, 74 are currently listed as threatened (including 11 species which are critically endangered) on the International Union for Conservation of Nature (IUCN) Red List. The IUCN has estimated that one quarter of all shark, ray and chimaera species are threatened with extinction.
While it is impossible to know how many sharks are killed yearly due to illegal and unrecorded catch, it is estimated that up to 73 million sharks are killed annually by “finning” alone—a brutal practice that involves cutting off a shark’s fins, usually while it is still alive, and throwing the body back overboard where it either bleeds to death or drowns. The fins are then used to make shark fin soup, a traditional Asian delicacy.
In addition to being taken intentionally for their fins, sharks are often accidentally caught up in fishing nets and on lines – a practice called “bycatch.” When lines are unattended, such as in some longline fisheries, the toll can be particularly high.
Size: The spined pygmy shark, a deep-sea shark, is one of the smallest at only about 7-8 inches, while the whale shark is the largest shark, and fish, at about 50 feet in length.
Lifespan: Although lifespan varies by shark species, most sharks are long-lived and generally tend to live for 20-30 years. Species like the spiny dogfish and the whale shark are believed to live for over 100 years!