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Just When You Thought It Was Safe to Go In the Water…

By: Jessie Quinn, Ph.D.

A star from shark week. Image courtesy of Hoax Slayer.

A star from shark week. Image courtesy of Hoax Slayer.

It’s almost Shark Week!  And what have YOU done for your friendly neighborhood sharks lately?

The State of California has done something.

On July 1, 2013, the California legislature officially enacted a ban on the sale, trade and possession of shark fins.  From now on, anyone caught in violation of this law faces a $1,000 fine.  And California was not the first; Hawaii, Washington, Oregon, Illinois, Maryland, Delaware and the U.S. territories of Guam, American Samoa and the Northern Mariana Islands have all passed similar bans in recent years, as well as the nations of Australia, Taiwan, and Canada.

Wondering what the big hubbub is about? Aren’t sharks cold-hearted, ruthless, man-eating beasts?  Did you see Jaws?!  What’s a couple of shark fins, especially when you consider the issue of human safety in our oceans?

The ratio of the yearly incidence of sharks killing humans vs. humans killing sharks should shock you. By the numbers, considering both intentional and unintentional harvest, recent estimates of shark mortality range between 63 million and 273 million individuals annually. Wondering what a person would need all of those sharks for? Good question!

Some of the mortality is unintentional; sharks are often killed as “bycatch” in the process of fishing for other species using longlines or purse seines.  This adds up to an estimated 55 million sharks per year.  The rest are hunted for their fins, a necessary ingredient in shark fin soup, which is considered a delicacy in Chinese cuisine. At one time the feat of obtaining a shark fin was understandably awe-inspiring. The extreme danger involved in catching and killing a shark with limited technology rendered its fin an incredibly rare item, usually only possessed by the extremely wealthy.

Today, however, the growing middle class in China and the increased wealth of traditional shark fin consumers worldwide have enabled millions of people to purchase shark fins. Despite the high average price of $100 per bowl and up to $2,000 for a pound of fins, demand has increased to a staggering 26-73 million shark fins a year.

An innumerable amount of shark fins due to the high demand for shark fin soup.  Image courtesy of the Decline of the Empire.

An innumerable amount of shark fins due to the high demand for shark fin soup. Image courtesy of the Decline of the Empire.

But sharks are pretty much just big, bony fish (you might think), and we already catch fish sustainably all the time at those numbers. Well, that is actually part of the problem. Sharks aren’t like other bony fish; most bony fish lay thousands of eggs, and produce young that grow quickly and reach reproductive maturity after just a few years. Sharks, on the other hand, gestate for 12 to 18 months, give birth to only 2 to 10 pups at a time, and don’t even reach reproductive maturity until they are 9 or 10 years old for males, and 14 to 16 years old for females.  This low reproductive rate suggests that sharks can’t possibly replace themselves at the levels of harvest they are experiencing.  And not surprisingly, they’re not.  Shark populations have declined an estimated 90% globally since 1975, and as much as 99% in some regions. An estimated 30% of shark species and their close relatives, ray species, are threatened with extinction or close to it, according to the International Union of the Conservation of Nature (IUCN).

Not only is this level of harvest unsustainable for sharks, but it may have a devastating effect on other species as well. Recent research has documented the critical role sharks play in maintaining some amount of stability in marine ecosystems, a phenomenon called a trophic cascade.  [In a trophic cascade, a top predator suppresses the populations of smaller predators or herbivores, thus maintaining populations of their food sources (smaller animals or plants)].

An example of a marine trophic cascade: An increase in Orca predation on sea otters in Alaska led to a decrease in sea otter numbers; which in turn likely caused an increase in sea urchin density (prey of sea otters); which then led to a decline in kelp forests due to increased sea urchin grazing.  From Estes et al 1998.

An example of a marine trophic cascade: An increase in Orca predation on sea otters in Alaska led to a decrease in sea otter numbers; which in turn likely caused an increase in sea urchin density (prey of sea otters); which then led to a decline in kelp forests due to increased sea urchin grazing. From Estes et al 1998.

One study found that as the number of sharks on the east coast plummeted, the numbers of their prey (predators themselves) increased, which in turn correlated with a dramatic decline in bay scallops. While there may be some debate as to whether this correlation equates with causation, it is certain that without understanding the role of these top predators in maintaining biodiversity, we cannot know the full extent of the impact of the huge population declines until it’s too late.

But there may be hope. Although the Jaws movies of the 1970’s (and 80’s if you count Jaws in 3D and Jaws: the Revenge, which I don’t) fostered little affection for what were portrayed as scheming, vengeful killers; the movies also fostered a dramatic increase in curiosity and respect for sharks. Even Peter Benchley, whose book inspired Jaws, became a long-time advocate for shark conservation and research.  Interest in the prospect of being eaten by a shark in one giant bite gradually transitioned to interest in the fascinating ecology of these ancient creatures.  For example: the 26th season of Shark Week begins on the Discovery Channel on August 4th. Twenty-six seasons!  That’s quite a shift in popularity from vicious, super predators to captivating creatures we strive to understand.

Most importantly, conservation efforts are well on their way. The Shark Conservation Act of 2011 greatly strengthened the Shark Finning Prohibition Act enacted by the U.S. government in 2000 and New York State is considering a ban on the sale of shark fins. Countries and grocery store chains across the globe have refused to sell or serve shark fin soup, and there are tasty, sustainable alternatives to traditional shark fin soup. The first shark sanctuary in the world was also established in the Republic of Palau.

So, just when you thought it was safe to go in the water, maybe it will be soon…that is, if you are a shark.

To do something for your neighborhood shark…

Comment on NOAA’s “Implementation of the Shark Conservation Act” which may pre-empt the shark fin ban.  Public comment period ends July 31.

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