Fascinating facts about sharks

Unlike some fish, sharks are internal fertilisers, meaning the egg and sperm come together inside the female shark's body. Some sharks lay their fertilised eggs on the ocean floor, and others give birth to live young (called pups).

Though sexual reproduction is the most common method among sharks, some species are capable of a process of asexual reproduction known as parthenogenesis, which is uncommon among complex vertebrates. One species with this ability is the zebra shark.

How many sharks are killed each year?

Humans kill an estimated 100 million sharks every year. That's an average of almost 274,000 sharks every day, over 11,000 sharks every hour, and around three sharks every second.

One way people kill sharks is through shark finning. This involves catching sharks, removing their fins, and discarding them back into the ocean, where they often die slow, painful deaths. Shark fins are in demand due to their monetary and cultural value. An estimated 23 to 73 million sharks are finned each year.

Bycatch is another way sharks are killed by humans. This is the unintentional catching of sharks in fishing nets.

Sharks are also hunted for their meat, internal organs, and skin to make food, leather, and other products. Shark meat has been shown to carry toxic amounts of substances like mercury and ciguatoxin.

How many people do sharks kill each year?

In contrast to the staggering number of human-induced shark deaths, fewer than 10 people worldwide are killed each year by shark attacks. For comparison, every year, about 24 people die after being hit by flying champagne corks, about 700 people die from toasters, and about 2,000 people are struck and killed by lightning.

Experts believe shark attacks on humans are usually unintentional. They are most likely cases of confused sharks mistaking kicking feet for small fish.

What threats do sharks face?

More than one third of shark species are currently threatened with extinction. Populations of sharks in the open ocean have declined by 71% over the past 50 years.

Much of these declines are due to global demand for shark meat and fins, which is pushing some shark species to the brink of extinction. Commercial fishing also impacts sharks through bycatch, when they are accidentally caught in fishing nets.

Meanwhile, sharks are also rapidly losing their homes. Shark habitats-particularly in coastal waters-are being destroyed by residential and commercial development, including through the cutting down of mangrove forests and pollution.

Sharks are particularly vulnerable to all these threats because they take a long time to reach sexual maturity, and most sharks only have a few pups at a time. Many sharks get killed before they have a chance to reproduce, making it difficult for their populations to rebound.

How do sharks help their ecosystems?

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