Sharks are endangered as an exclusive result of human impacts and activities. Today, the main shark threats include commercial shark finning (for traditional medicine and shark fin soup) and entanglement in commercial fishing gear.
Sharks are apex predators, meaning they sit at the top of their food chain, and they play an important role in the overall health of the oceans. Other shark threats include habitat degradation and climate change.
The entire ocean ecosystem is affected by declining shark populations. Sharks are long-lived, mature late, and they produce few young (pups), making them especially vulnerable to exploitation.
In the March 30 issue of the journal Science, researchers reported a 1970 – 2005 study on populations of 11 great shark species. In every instance, samples showed a drastic decline in the 35-year study window. The Sandbar Shark showed the smallest observed decline at -87%. Meanwhile, the other 10 remaining species, including Hammerhead Sharks, Bull Sharks, and Dusky Sharks have each declined by – 99%.
What does a decline in shark populations mean?
Scientists have observed that ecosystems are essentially a fragile network of actors each playing a unique role in the creation of balance. When one actor (a predator in this instance) is removed from an ecosystem, the next-in-line actors blossom, albeit temporarily. Their population can rise so swiftly that they often overeat their prey to the point of extinction. The result, and without any food left to eat, is a form of unintentional suicide.
The biggest threat to sharks, skates, and rays is overfishing. Shark fins are particularly sought after for both traditional Chinese medicine and shark fin soup – considered a delicacy in Asia. Watch a 5min video on Shark Finning by Tulley Beard.
Commercial shark-finning is where sharks are caught, their fins cut off, and body discarded. Shark finning kills an estimated 100 million sharks per year.
Commercial fisheries are also having a major impact. Bycatch is the unintentional capture of a non-target species. Fisheries targeting tuna and billfish, in particular, have a high impact on sharks.
Rays and skates are also under threat from unintentional capture in commercial fisheries. They are greatly impacted by bottom trawl fisheries as they are mainly bottom dwellers. Bottom-dwelling sharks are also impacted by this fishery.
All sharks depend on healthy ecosystems to survive and find prey. Habitat degradation includes effects from climate change, pollution, and destruction of areas, such as mangroves and reefs. These areas are used for both breeding and finding prey, and they provide protected habitat for young sharks pups.