As 177 nations gather in Bangkok this week to deliberate trade restrictions on potentially endangered animals, new research reveals how important these deliberations are to the long-term survival of five species of sharks.
A study published March 1 in Marine Policy reported new, higher estimates for the numbers of sharks killed yearly: approximately 100 million sharks. Meanwhile another study published February 20 in PLoS ONE, describing the migratory patterns of the highly threatened oceanic whitetip shark, reveals why international cooperation may be the last option available to preventing this shark's extinction.
Among the 71 proposals being considered by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in Bangkok March 3–14 are four involving marine species. The proposals would move the oceanic whitetip shark, the porbeagle shark, all three species of hammerheads and all species of manta rays to an Appendix II listing, which requires anyone wishing to trade them to first procure a permit. The whitetip, porbeagle and scalloped hammerhead all had proposals considered at the last CITES meeting in 2010 but each narrowly missed the two thirds majority needed for adoption.
But shark researchers and conservation specialists hope that the new research showing just how threatened these sharks are might be enough this year for these sharks to join the only three other sharks listed on Appendix II: the whale shark, the basking shark and the great white.
“CITES is going to be a dialogue between nations that want to protect their sharks and the financial interests that want to see maximum yield and maximum sustainable yield,” says Rick MacPherson, the conservation programs director at the Coral Reef Alliance. Those nations wanting to protect sharks include an unusually high 37 countries this year. “However, the number for maximum sustainable yields are probably overestimated,” he adds.
That unsustainable level of shark fishing is exactly what the new Marine Policy paper shows. Annual shark mortality was previously estimated at 73 million, but this study added reported catch at the U.N. Food and Agriculture Organization and estimates of unreported landings and finned sharks for an estimated range of 63 million to 273 million sharks killed each year.
Barriers to protection
Sharks face a triple threat: “They are really migratory, have a really low reproductive capacity and are subjected to heavy fishing driven by a demand for international trade,” says Elizabeth Wilson, the manager of the Global Shark Conservation Campaign at the Pew Charitable Trusts, who partly funded both new studies. On top of that, few regulations and “fragmented governance”—the patchwork policies across all the countries’ waters where sharks roam—impede meaningful shark protection strategies.
“Just the fact that they migrate between political jurisdictions complicates things,” says David Shiffman, a graduate student in ecosystem science and policy at the University of Miami. “Even if one or two countries are responsible with fisheries management, if the animal doesn’t spend all its time there, then it can still be severely overfished.” In the oceanic whitetip study, Demian Chapman, of the School of Marine and Atmospheric Sciences at Stony Brook University, S.U.N.Y. and colleagues attached pop-up satellite tags to 11 oceanic whitetips off Cat Island in the Bahamas in May 2011. All but one tag reported data for up to 245 days and revealed that the sharks spent about 68 percent of their time in the Bahamas’s Exclusive Economic Zone, where long-lining and commercial trade of sharks is outlawed. The rest of that time they roamed more than 16,000 square kilometers of ocean, traveling nearly 2,000 kilometers from the safe Bahamian waters.