I was being towed behind a small boat 150 km from shore and counting reef fish as part of my underwater surveys on the Great Barrier Reef. On one side of me the water was about 10 metres deep, bright and colorful with coral and fish and then it plunged down to nearly 1000 metres of icy darkness just beneath me.
I’d had company since I first dived into the inky water. Just on the edge of my visibility a pair of Oceanic Whitetip Sharks, Carcharhinus longimanus, had followed my every move.
All I could see of them was the silvery tips of their huge pectoral fins. Growing to four metres and 170 kg and considered responsible for most open ocean shark attacks, these elegant fish are nature’s ultimate predator and were my biggest worry.
That was 30 years ago and Oceanic Whitetips were always around me. The last time I dived the outer Barrier I was alone. In 1969, Lineaweaver and Backus wrote of the Oceanic Whitetip: “[it is] extraordinarily abundant, perhaps the most abundant large animal - on the face of the earth”. Now overfishing has brought about a catastrophic collapse in their numbers. The International Union for the Conservation of Nature lists them as “Critically Endangered” in the Northwest and Central Atlantic and “Vulnerable” globally.
But the Oceanic White Tips are not alone in this tragedy. “There is mounting evidence of widespread and ongoing declines in the abundance of shark populations worldwide” says Mizue Hisano from the ARC Centre of Excellence for Coral Reef Studies at James Cook University. ”Overfishing of sharks and shark finning are now recognized as a major global conservation concern, with increasing numbers of shark species added to the International Union’s list of threatened species,” he says in the latest issue of the science journal PLos ONE.
More species were added to the Convention on International Trade in Endangered Species (CITES) during the Conference of Parties meeting in Bangkok, Thailand, March 3-14 of this year. Sadly, the nations of the world were voting on the restriction of international trade only in “endangered sharks”. This may not be enough as the fishery will quickly shift to other less desirable species to meet its growing demands. The shark industry is worth about US$630 million annually according to a study published May 30, 2013 in Oryx – The International Journal of Conservation.
Shark meat is low priced so fishermen try to fill their boats with only the valuable fins. Contrary to a UN Resolution to ban the practice, the fins are usually sliced off (shark finning) the shark while it is still alive. The cheaper body is thrown back into the ocean and the shark, unable to swim, dies slowly. Shark fin purchases are increasing at the rate of five percent per year in mainland China even though sharks are becoming harder to catch as their numbers fall.
On March 1, 2013, “Global Catches, Exploitation Rates and Rebuilding Options for Sharks,” was published by Dr. Worm and three other researchers from Dalhousie University teamed up with scientists from the University of Windsor in Canada, as well as Stony Brook University, Florida International and the University of Miami.
Their shocking findings are that shark fishing is now globally unsustainable. Their more recent estimates put the carnage at 97 million in 2010. The possible range of mortality is between 63 and 273 million annually. This equates to somewhere between 7,200 and 31,000 sharks per hour.
Scientists from the International Union for the Conservation of Nature (IUCN) now agree that more than half of many large shark species have virtually disappeared because of the unprecedented demand for shark fins. At current rates of decline, there will be no shark fins and unfortunately very few sharks by 2030.
A research team, which included researchers from Microwave Telemetry, Inc., the Cape Eleuthera Institute, and the Institute for Ocean Conservation Science, attached satellite tags to mature Oceanic Whitetip sharks in The Bahamas.
Their findings, published February 20, 2013 in the journal PLoS ONE, show that some of these sharks roamed nearly 2,000 kilometers but all individuals returned to The Bahamas within a few months. Protecting endangered Whitetips in signatory countries will have little effect if they travel into unprotected seas.
So why are shark fins attracting such attention?
Shark fin soup is a delicacy served at Chinese weddings and other celebrations for centuries (since Ming Dynasty). Recently this expensive product has become part of business dinners in Southeast Asia. Because the fins are the most expensive part of the shark, having them on the menu is a sign of prosperity.
Oceanic Whitetips belong to an ancient group of fish and produce from one to 15 pups after a year’s gestation. They are unable to produce enough pups to balance the high fishing rates and so the number of sharks gets smaller each year. But the Oceanic Whitetip is at the top of the food chain and its abundance regulates the ecological relationships of all the marine life in the complex web of predator and prey beneath them.
Within 30 years shark fin soup will no longer symbolize prosperity. Instead it will be a tribute to man’s greed and lack of commitment to his own future.
