07/27/2012 05:35 pm ET Updated Sep 26, 2012

Surviving the Shark

Have you ever had the feeling you're not alone in the water? That edgy sensation makes you search the ocean, wondering if something could be out there with you? Suddenly, all your friends seem far away. You have a sensation that something is so close you might touch it, but you can't see anything. The feeling makes you shiver. You try not to panic as your imagination races. You hope you won't see a fin slice the water as you race to shore.

Recent great white shark sightings on both the East and West Coasts have given us reason for panic. Sightings by kayakers, surfers, and beachgoers confirm that a shark can appear suddenly, even close to shore. Why are we so fearful of them?

We all know sharks live in the ocean, but we don't expect to see one. And yet an image in our minds causes us to fear that a shark might be checking us out. Sometimes that feeling is true. Or was it only seaweed?

It happened to me on a summer day at Stinson Beach, a few miles north of San Francisco, on the Pacific coast. My legs dangled off my board as I floated in the waves 50 yards from shore, waiting for the next good wave. Suddenly my hand bumped something under water and I had that shark-y feeling. I searched the water in every direction. The ocean looked dark and empty, but I knew something was out there with me. Somehow everything and everyone else had vanished. I knew I was swimming with a shark. I had to get out of there, fast.

When you think there's a shark, you swim with all your might and hope you can make it to shore before the shark comes back for you. But the shark is a faster swimmer and it uses camouflage to its advantage in the dark water. It attacks from below and behind, using sophisticated senses to locate its prey. The element of surprise is terrifying. You first sense the shark as it moves below you, displacing large volumes of water. You feel a surge. Then the water ripples, and the surface breaks. The hit is overwhelming. It slams into you full force and you feel the massive power and speed. When the teeth of a great white shark sink into your flesh, you know immediately what's happening.

How can you possibly hope to defend yourself against this massive creature? How can you get away without losing your leg, or your life? How do you fight back against an animal so big you can't get your arms around its body? In a battle with this superior predator, you save what you can.

The great white shark is an apex predator, and yet we are more of a danger to sharks than they are to us. Sharks are threatened with extinction in every part of the world. The greatest enemy of the shark is man. We people kill millions of sharks every year just for their fins. Great whites are victims of accidental by-catch, longlines, fishing nets, beach protection, and sport fishing. Sharks are critical to our marine ecosystem and they need our protection.

Great white sharks don't really want to bother us. In fact, people have tested this theory by swimming with them, untouched. But, when the shark sees you on the surface of the water, your silhouette from below looks like a seal. The shark may decide to investigate. Unfortunately that first hit can be a huge mistake.

I don't blame the shark for what happened to me. Whenever you're in the ocean you're in the home of the shark. Generally, except for a very small margin of error, the sharks will leave you alone.

Jonathan Kathrein and his mother, Margaret, live near San Francisco. They have just published their new book: 'Surviving the Shark' (Skyhorse Publishing).

Other books by these authors:

'Don't Fear the Shark'

'Far From Shore, A Mother's Memoir of a Shark Attack'