Ocean Currents

Western Australia Shark Cull

© Matthew Potenski, 2011 photo contest

Many species of sharks and rays around the world are in trouble, and current events in Australia remind us of that. The government of Western Australia is presently implementing a controversial “shark cull” policy in response to recent highly publicized shark attacks near Western Australian beaches. The policy consists of deploying baited hooks about a mile off of various Western Australian beaches, aimed specifically at catching large sharks. Any shark larger than 10 feet is viewed as a threat to public safety and is to be “humanely” killed; the main targets of the cull are tiger sharks, bull sharks and great white sharks. Great white sharks are a protected species in Australia, and state authorities were given a special exemption from Australia’s Environment Protection and Biodiversity Conservation Act to be able to kill them. The shark cull is a pilot program. If it were to continue after the April 30 trial period ends, there would have to be a full environmental act assessment.

The public outcry in Australia and around the world about the shark culling policy is indicative of the sea change in public attitudes toward sharks that has been occurring over the past decade. People around the world are growing increasingly concerned about that status of sharks and rays and are opposing what is viewed as senseless killing of an important ecosystem component. Unfortunately, the major threats to sharks and rays around the world are much less publicized than the high-visibility Australian shark cull, which has a comparatively small impact on global populations.

A scientific study published this month in the journal eLife concludes that about a quarter of the world’s sharks and rays are threatened with extinction, according to the International Union for Conservation of Nature Red List criteria. While the study identifies habitat loss, persecution (such as the Australian cull) and climate change as threats to sharks, the No. 1 threat remains overfishing. Some sharks are being directly targeted by fishing fleets while others are caught incidentally as bycatch in other fisheries. The global shark fin trade is a major driver for shark fisheries, but so is the demand for meat and liver oil. Most catches of sharks and rays are unregulated and unmonitored, and the shark fin market is also largely unregulated. In the United States, Ocean Conservancy supported California’s ban on shark fins in order to help curb the global demand for fins, which is fueling the trade.

Sharks and rays are more vulnerable to overexploitation than most fish in the ocean. They are slow-growing and long-lived, mature late in life, and have few young. The species most vulnerable to the fishery are the larger-bodied sharks and rays that inhabit shallow waters easily accessible to the fishery. Many of the biodiversity hot spots for sharks occur in areas where the threats are highest, for example in the Indo-Pacific and the Mediterranean Sea where population declines are most severe. Scientists are not aware of any global extinctions of sharks and rays, but there have been regional extinctions and a few species have not been seen in decades. One species that has experienced local extinctions is the smalltooth sawfish, the first marine fish to be listed in the United States under the Endangered Species Act, with the help of Ocean Conservancy and other groups in 2003.

Effective shark conservation requires attention to all of the major threats that sharks and rays face. It requires monitoring international catches and trade, assessments of the status of local populations, and implementation and enforcement of effective regulations to prevent further population declines and allow recovery of overfished populations. This is challenging in many of the poor countries where the problems are most severe due to lack of effective governance mechanisms and funding for conservation and management. Australia, in spite of the heavy criticism it has drawn for the current shark cull, is one of the few nations in the world with a relatively effective monitoring, assessment and management system in place, for sharks and other fisheries. Given the condition of the world’s shark and ray populations and their important role in ocean ecosystems, it’s important that policies protect and conserve these vital species.


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