Predators as Prey: 10 Threatened Shark Species - Oceana USA
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August 4, 2010

Predators as Prey: 10 Threatened Shark Species

We often tell you about the threats facing sharks globally — finning, bycatch, overfishing — but we don’t regularly shine a spotlight on the individual species affected.

To continue our ongoing shark-themed posts in honor of Shark Week, here are 10 of the most threatened shark species in the world:

1. Basking sharks are the second largest shark, easily distinguished by their huge, filter-feeding mouths. Basking sharks are caught in target fisheries around the world for their oil, meat and fins, and they are also caught as bycatch in other fisheries.

2. Blue sharks are one of the most previously abundant shark species. Now they are the most heavily fished shark in the world. An estimated 10-20 million individuals are killed by fisheries annually, mostly as bycatch. Blue shark meat is beginning to replace swordfish in many Mediterranean countries and the fins are commonly used in shark fin soup.

3. Deep-sea sharks have huge livers that contain high amounts of oil to regulate their buoyancy at depths. As a result, they are caught by deep-sea trawls, gillnets and longlines for an oily substance found in their livers called squalene. Squalene, or its derivative squalane, is found in many cosmetic products.

4. Great white sharks, despite their fierce reputation, are far more threatened by humans than vice versa. Even though they are protected internationally under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), great whites continue to be targeted for their teeth and jaws, which are sold on the black market.

5. Scalloped hammerhead fins are extremely valuable for use in shark fin soup and the scalloped hammerhead is taken both as a target species and as bycatch. The meat, skin and oil are also utilized. The scalloped hammerhead has declined by more than 75 percent in the past 15 years along the eastern U.S. and is listed as “Endangered” on the IUCN Red List.

6. The whale shark is the world’s largest fish, at an average length of 14-20 meters. A majority of whale sharks are caught before they even reach maturity. Overfishing is a serious concern as whale shark populations are decreasing in numerous regions and the average size of Australian whale sharks is shrinking.

7. Spiny dogfish are caught for a variety of purposes including fish and chips, shark fin soup, fertilizers, liver oil, pet food and as a popular dissection specimen in academic science labs. A highly valued species in Europe, the spiny dogfish is targeted in many trawl and line fisheries.

8. The porbeagle shark is caught as a target and bycatch species in commercial fisheries for its high-value meat. Directed longline fisheries seriously depleted the northeast Atlantic population and less than one percent of the Mediterranean population remains from a century ago.

9. The sandbar shark is harmless to humans and has larger-than-normal fins, making it the most valuable large coastal shark species for fishermen. Commercial and recreational fisheries target the sandbar shark for its meat, use in shark fin soup and as a game fish.

10. The dusky shark is one of the slowest growing sharks in the world; it takes 20 years to reach maturity and has a 16 month gestation period. This slow growth rate means dusky sharks are particularly vulnerable to exploitation. The Gulf of Mexico population suffered a 79 percent decline between the 1950s and the 1990s.

You can learn more about these and the other shark species at risk on our Shark campaign page, and you can help protect them by telling your Senator to support the Shark Conservation Act.

Come back tomorrow for five ways to help save sharks!