Worried About Shark Attacks? The Sharks are the Ones That Should be Scared

With Shark Week drawing to a close, the ocean’s top predator is swimming through many Americans’ minds. But even if you haven’t been tuned in to the Discovery Channel, you might have heard that there were 79 shark attacks in 2010, up 25 percent from the year before.

That’s not quite correct. There were actually millions of shark attacks last year. In all but those 79, the sharks were the victims.

We’ve all heard that the chances of getting bitten, not to mention eaten, by a shark are extremely low, as humans are not sharks’ normal prey. But it only takes a few horror stories (and a blockbuster film or two) to make us fear and loathe the cartilaginous hunters.

The truth is that sharks have much more reason to be afraid of us. Worldwide, less than 10 people per year die from shark attacks, while between 20 million and 100 million sharks are killed by humans. Some sharks are killed for sport, but most are killed for profit, the fins being especially valuable. As renowned oceanographer Sylvia Earle explains in her book The World is Blue, 

In 1980, designated as the “Year of the Ocean” in the United States, a perverse but well-intended campaign was intiiated at NOAA to help fishermen by developing markets for sharks as “underutilized species” and by fostering new connections to Asian consumers. In two decades, fears about man-eating sharks shifted to man…eating sharks….

For centuries, soup made from the fins of sharks has been a traditional but rare treat in China, the primary attraction being the difficultury of obtaining the vital ingredients…. By the end of the 20th century, however, new wealth in Asia and new means of finding, catching, and marketing sharks made shark-fin soup much more commonplace.

Because shark fins are in higher demand than meat, fishermen haul their catches on deck, slice the fins off, and throw the still-living sharks overboard. As many as 73 million sharks die each year from this practice.

Shark finning is illegal in the U.S., but a loophole allows shark fins to be imported into California. Ocean Conservancy, NRDC, and other conservation groups are campaigning for a bill to ban the trade of shark fins–you can sign the petition here, even if you don’t live in California. Change.org also has a petition asking Food Network to stop featuring recipes that include shark meat.

Sharks have survived for 400 million years, but humans may manage to wipe them out in a geological heartbeat. About a third of shark species are endangered, with some populations declining 90 percent in recent years. And any ecologist will tell you that eliminating top predators can have a disastrous effect on an ecosystem.

Of course, sharks aren’t the only fish in trouble. After decades of irresponsible fishing, we are beginning to realize that the ocean does not have an infinite capacity to restore wildlife. In 2003, nearly a third of marine fisheries were in a state of collapse, and research indicates that the remaining stocks could be gone within 50 years.

Entire books have been written on the causes and impacts of this decline, but the solutions are not out of reach. In your daily life, you can choose to buy sustainable seafood (Monterey Bay Aquarium’s guide will help you with that). On a political level, you can join the effort to restore the oceans–for example, Mission Blue, founded by the brilliant Ms. Earle, is working to establish marine protected areas, or “hope spots.”

We named our planet Earth because that’s where our species dwells, but it would be more accurate to call it Ocean. We hear a lot about saving the earth; now we need a new worldwide effort to save the seas. Sharks are a good place to begin.

And if we can save the oceans, we just might save the humans in the process.

[Image: Wikimedia Commons]


Carbon in the Ocean: More Dangerous than Oil in the Gulf?

Cross-posted from the RYSE blog.

It will soon have been five months since the Deepwater Horizon exploded and the ensuing disaster spilled across headlines. Being particularly awful, the Gulf oil spill occupied the spotlight longer than many catastrophes do. But now the leak is under control; the oil is being cleaned up. Heck, 74 percent just disappeared, according to the government.  The media has moved on, and life with it.

Actually, most of the spilled oil was still in the Gulf in early August, when an independent team of oceanographers released their study. But that’s another story. In light of the past summer’s events, you could be forgiven for thinking that oil spills are the worst way fossil fuels impact the ocean. You’d still be wrong, though.

When everything in the oil production process works perfectly, the oil remains safely in the pipelines, on the tankers, in our engines. But when we burn the oil, we create a carbon dioxide “spill” far more widespread than the Deepwater Horizon’s slick. Since you’re reading an environmental blog, you probably know how CO2 affects the climate, so I won’t go into that.

But out of all CO2 released by burning fossil fuels (around six billion tons) only about half increases CO2 levels in the atmosphere. The rest goes into the oceans, where it converts to carbonic acid, raising the water’s acidity. In her book The World is Blue, Sylvia Earle, the world-renowned oceanographer, writes,

A change in acidification can cause trouble for everything from developing fish to jellyfish. Alter the chemistry of the ocean and the entire system shifts.

For example, the structure of coral reefs depends on corals (obviously), as well as red and green algae. These organisms dissolve when acidity reaches a certain level. And if coral reefs collapse, so do the vibrant communities they support.

Ocean acidification could also alter the oxygen and carbon cycles. Photosynthetic marine organisms absorb more carbon and produce more oxygen than do their land-based counterparts. So, by pumping CO2 into the oceans, we are possibly changing the balance of gases in the air we breath.

Returning to Sylvia Earle,

Some natural changes we can predict, but it is impossible to anticipate how fast, or how much will occur as a consequence of tipping the ocean’s chemistry onto a different course.

Examining the past can give us some clues, though. A study published in Nature Geoscience reported that oceans are acidifying ten times faster than they were 55 million years ago, when a mass marine extinction occurred (read Carl Zimmer’s article for details). Of course, CO2 was not the only factor in ancient climates, but one thing continues to be clear:  CO2 levels are rising much faster now than they have throughout most of the earth’s history, and speculation is quickly becoming observation.

We’re experimenting with the environment that allows our civilization to thrive. But unlike typical scientists, we only get one chance.

Image: Flickr user Paul Mannix