by Amanda Levine
There are over 100 million sharks killed every year to fill bowls of shark fin soup in China. That’s more than 3 times the population of the state of New York! Before the year 2000, shark fishing activities went largely unnoticed. Many species of shark were caught all over the world, their fins removed and shipped to Hong Kong. Since the fin was the only part of the shark deemed “valuable” to the fisherman, the shark’s still living body would then be thrown overboard to die a slow death.
This disgusting act known as “finning” was practiced throughout the world to support the huge demand in China. Although the media has famously portrayed sharks as dangerous man-eaters in movies like Jaws, scientists have a very different view of these incredible animals. Their existence is vital to the ocean, as loss of sharks can result in the degradation of aquatic habitats, especially delicate locations like coral reefs and seagrass beds. The loss of these fragile places decreases local fish populations, which increases economic strain on coastal communities. Today a number of shark species are internationally protected to combat this decay. In order to truly protect sharks and promote conservation efforts, organizations and governments need to know which species are being affected the most.
The conservation of sharks is not easy. The first step in protecting sharks is identifying at-risk species being sold in Chinese fish markets, a process filled with obstacles. It is difficult to even acquire the fins to be identified, due to the high costs and extreme measures that many of these Chinese fish markets go to in order to stop anyone attempting to get samples. Even when samples can be acquired, the identification process can be complicated. Shark fins tend to look alike, making it nearly impossible to distinguish them by sight. Scientists, however, are capable of discriminating between the species by the fins’ DNA (genetic code), which is unique to each species. They use a technique called polymerase chain reaction to amplify certain pieces of the DNA, which is then analyzed to identify the species.
Unfortunately, the DNA in shark fins on the market is often degraded after having gone through chemical baths and processing. These roadblocks have prevented the scientific community from adequately protecting sharks or even identifying if current conservation methods are working.
Dr. Demian Chapman and Ph.D candidate Andrew Fields of Stony Brook University’s School of Marine and Atmospheric Sciences have devised a solution for identifying these shark fins more effectively. During a trip to Hong Kong, they found that some shark fins were cut up into smaller, potato chip-sized pieces and sold cheaply in mixed bags. By buying these “off-cuts” they could buy lots of samples for a fairly low price; however, the DNA was still degraded, complicating the identification process. They had to invent a brand new method to identify the fins. They tweaked the current technology used to amplify DNA, so that only a smaller section of a specific gene, the cytochrome oxidase I gene, had to be amplified. By using this method, they could identify even the processed fins!
Unfortunately, it seems that the shark fin trade is bigger than was previously thought. After using this test on hundreds of off-cuts, Fields says, “There seems to be no safe group [of sharks].” Small and large sharks from all over the world, from the tropics to the subarctic seas to the deep sea, have been identified. Most shocking of all is the presence of internationally protected species in these samples. Hammerhead sharks were recently added to the Convention on International Trade in Endangered Species, or CITES, and seeing them pop up in the shark fin trade through this research has shown that these conservation efforts may be failing. Now that scientists can identify shark species at risk, we can continue to shine a light on these issues and help protect our oceans.
Issue 1, October 2015