The end of commercial fishing is predicted long before the middle of the 21st century.

The value of sharks' lives is now widely understood to be more important than their value as products. And when you have sharks in an area, it's a sign of good health. They're top predators, which means they feed on old, sick, and slower fish, keeping an entire population healthy.

The diversity of life on Earth, generally, is astonishing. But despite those large numbers, it's also important to recognize that every species, one way or another, is vulnerable to extinction. And in our time on Earth... our impact on the diversity of life has been profound.

Humans have always wondered the big questions, "Who am I? Where have I come from? Where am I going?" It's part of human nature. It's perhaps the underpinnings of religion.

Fortunately, we know more about the problems that we have than in all preceding history. We know now the consequences of the things that we put into the air, into the water - of the way we treat life on Earth.

Many of us ask what can I, as one person, do, but history shows us that everything good and bad starts because somebody does something or does not do something.

When I write a scientific treatise, I might reach 100 people. When the 'National Geographic' covers a project, it communicates about plants and fish and underwater technology to more than 10 million people.