Throughout my teens and early twenties, I read most of the accessible literature on sharks—there wasn’t much—and in 1964, I read an item in a newspaper about a fisherman who harpooned a 4,500-pound great white shark off Long Island. I remember thinking at the time, Lord! What would happen if one of those monsters came into a resort community and wouldn’t go away? I tucked the item into my wallet and, for the time being, forgot about it.

Then, in 1971, a documentary feature film called Blue Water, White Death was released. It told the story of an expedition led by Peter Gimbel, a department-store heir and professional adventurer, to find and film a great white shark. Blue Water was then and, in my opinion, remains today the finest film ever made about sharks. In the same year, Peter Matthiessen’s wonderful book about the expedition, Blue Meridian, was published, and the two events not only affirmed (in bronze) my fascination with sharks but also set storytelling wheels turning in my brain.

I had no interest in writing a one-note horror story: Shark eats people. I concentrated on the question of what would actually happen if a huge predator laid siege to a resort community. The first reaction of the authorities, I thought, would be to try to cover up the problem in hopes that it would go away. Some resort communities earn 80 or 90 percent of their annual income during the three months of summer, and a shark-attack panic could destroy a summer’s trade. Of course, by the time of the second or third fatal attack, the cover-up would be impossible to sustain.

Who would be the authorities? A police chief, probably, and wouldn’t it be interesting if he was a man who feared and hated the water? Who would his wife be? Would they have children? Wouldn’t they seek help from an authority on sharks? A marine biologist, say, whose ambition would be to study the shark, not to kill it. And how would the town react to the outsider?

All these questions, and ten thousand more, assailed me as I began to tell the story to myself. Soon, the story began to tell itself, and once in a while, the characters would run away from me, dashing off in different directions. I would rein them in and talk to them and determine whether or not their destinations were appropriate.

At the time I was writing Jaws, the environmental movement we know today didn’t exist. Yes, there was a constituency building to save whales; yes, people were aware that pollution of air and water was a problem; yes, pesticides and other toxins were being recognized as dangerous to birds and fish. But to the general population, the oceans remained as they had always been—eternal, invulnerable, capable of consuming and rendering harmless whatever mankind threw at or in them. As for sharks … well, only a handful of people on the planet knew anything about sharks. To most people, and especially to fishermen and divers, the hoary canard about sharks was gospel: The only good shark is a dead shark.