A new global scientific review shows that simple changes in fishing gear could significantly reduce the large number of sharks unintentionally caught in the world's oceans. The paper, “Fisheries Bycatch of Sharks,” released today by the Pew Environment Group, outlines practical options for reducing shark injury and death from commercial fishing, a leading cause of shark population decline.
Although sharks are not the primary target of most fisheries, they can make up the majority of the catch in some regions of the world. Pew's Ocean Science Division worked with two scientific experts to research options to reduce shark bycatch, which occurs when the animals are caught in fishing gear set for other species. Viable modifications found by the researchers include changing the type of bait; switching the material used to create leaders, which attach fishing lines to hooks; and modifying the shape of hooks. Fishermen sometimes use wire leaders to maximize shark catch, but replacing the wire with nylon can allow sharks to break free because they can bite through the line.
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“Banning wire leaders and not allowing vessels to retain certain species would help reduce the vast number of sharks caught and killed in Atlantic fisheries,” said Jill Hepp, manager of global shark conservation for the Pew Environment Group. “The International Commission for the Conservation of Atlantic Tunas meeting is a good place to build support for using some of these new methods to avoid catching sharks in the first place.”
The scientific review, released at the annual meeting of the International Commission for the Conservation of Atlantic Tunas (ICCAT) in Istanbul, reports that in the U.S. Atlantic, sharks made up 25 percent of the total catch of the pelagic (open ocean) longline fishery between 1992 and 2003. In 2009, fishing vessels belonging to ICCAT members reported catching 58,100 metric tonnes of blue sharks, 264 metric tonnes of porbeagles, and 5,605 metric tonnes of shortfin makos in the Atlantic.
The convention's scientific committee says progress has been made in recent years to protect bigeye thresher, oceanic whitetip, and hammerhead sharks in the Atlantic. The committee recommends that silky sharks receive the same level of protection, since these animals were classified in ICCAT's most recent Ecological Risk Assessment as being among the most vulnerable species.
“While enhanced protections are now helping to safeguard certain species, the majority of sharks remain under threat due to countries' overall lack of political will to control the amount of bycatch hauled in by their fishing vessels,” Hepp said. “This review spells out clearly that there are plenty of options available to make fishing more sustainable when it comes to sharks, which, coupled with better fisheries management, would go a long way toward protecting these animals.”
The increasing demand and high prices for shark fins means fishermen have little motivation to release these animals while they are still alive. Up to 73 million sharks are killed every year, primarily to support global demand for fins, which are prized in Asia as a delicacy in soup.