A new report, published in the journal Marine Policy, assesses the the impact of commercial fishing on sharks and estimates that around 100 million sharks are being killed each year. The rate is higher than sustainable for most shark species and is believed to driven by the continued demand for shark fins for soup in China. There is hope that proposals to regulate the trade in five of the most threatened species of shark will be approved at the the meeting of the Convention on the International Trade in Endangered Species now being held in Bangkok, Thailand. Similar proposals narrowly failed in the previous meeting in 2010.
Why is the survival of sharks so important? Sharks are critical to maintaining the balance in ocean ecosystems. Over-fishing of sharks on the Eastern Seaboard of the United States, has, for example, wiped out the bay scallop fishery in North Carolina. Species of rays and skates, which were once kept under control by sharks, feed on bay scallops, oysters, and soft-shell and hard clams. The increased numbers of skates and rays have been disastrous for North Carolina’s bay scallop fishermen.
Sharks play a very important role in the oceans in a way that an average fish does not. Most sharks serve as top predators at the pinnacle of the marine food pyramid, and so play a critical role in ocean ecosystems. Directly or indirectly they regulate the natural balance of these ecosystems, at all levels, and so are an integral part of them. As they usually hunt old, weak or sick prey, they help to keep the prey population in good condition, healthy and strong, enabling these more naturally fit animals to reproduce and pass on their genes. The effects of removing sharks from the ocean ecosystems, although complex and rather unpredictable, are very likely to be ecologically and economically damaging.
Thanks to Alaric Bond for contributing to this post.