The author of The Book of Sharks, Imagining Atlantis, and Encyclopedia of the Sea turns his gaze to the tuna?one of the biggest, fastest, and most highly evolved marine animals and the source of some of the world?s most popular delicacies?now hovering on the brink of extinction. In recent years, the tuna?s place on our palates has come under scrutiny, as we grow increasingly aware of our own health and the health of our planet. Here, Ellis explains how a fish that was once able to thrive has become a commodity, in a book that shows how the natural world and the global economy converge on our plates.

The longest migrator of any fish species, an Atlantic northern bluefin can travel from New England to the Mediterranean, then turn around and swim back; in the Pacific, the northern bluefin can make a round-trip journey from California to Japan. The fish can weigh in at 1,500 pounds and, in an instant, pick up speed to fifty-five miles per hour.

But today the fish is the target of the insatiable sushi market, particularly in Japan, where an individual piece can go for seventy-five dollars. Ellis introduces us to the high-stakes world of ?tuna ranches,? where large schools of half-grown tuna are caught in floating corrals and held in pens before being fattened, killed, gutted, frozen, and shipped to the Asian market. Once on the brink of bankruptcy, the world?s tuna ranches?in Australia, Spain, France, Italy, Greece, Turkey, and North Africa?have become multimillion-dollar enterprises. Experts warn that the fish are dying out and environmentalists lobby for stricter controls, while entire coastal ecosystems are under threat. The extinction of the tuna would mean not only the end of several species but dangerous consequences for the earth as a whole.

In the tradition of Mark Kurlansky?s Cod, John Cole?s Striper, John Hersey?s Blues?and of course, Ellis?s own Great White Shark?this book will forever change the way we think about fish and fishing.

• Tuna is the most popular food fish in the world. It is eaten raw, cooked, in sandwiches, in salads, and in catfood.
• The total worldwide tuna harvest is four million tons.
• In the past, tuna fishermen in the eastern tropical Pacific set their nets around dolphins, which resulted in the deaths of tens of millions of dolphins.
• There are many kinds of tuna, but the most popular for the Japanese sashimi market is the bluefin, one of the largest of all fishes.
• The largest bluefin tuna ever caught weighed 1,496 pounds.
• The most expensive bluefin tuna was a 440-pounder that sold at the Tsukiji fishmarket in Tokyo for $173,600.
• Almost all of the bluefin tuna caught by commercial fishermen goes to Japan.
• The Japanese import 800,000 tons of tuna every year. (That?s right: eight hundred thousand tons.)
• At the Tsukiji fishmarket in Tokyo, an estimated 1,000 bluefin tunas are auctioned off every day.
• Is there mercury in tuna? Yes. Is it at levels dangerous to humans? Not unless you eat tuna three meals a day.
• Many scientists consider the tuna the most highly-evolved fish in the world.
• Bluefin tunas, along with mako and great white sharks, are the only "warm-blooded" fishes; they can elevate their body temperature as much as 25 degrees above the water they swim in. This makes them particularly effective as predators.
• Bluefin tuna can swim 55 miles an hour. They can migrate across the Pacific and Atlantic Oceans, then turn around and do it again.
• MIT scientists built a robot tuna in an attempt to replicate the incredibly efficient swimming performance of the living fish. They failed.
• The bluefin tuna, and to a lesser extent, the yellowfin, are among the most sought-after of big-game fishes. Celebrated anglers like Zane Grey, Ernest Hemingway, and Phillip Wylie wrote ecstatically about their pursuit of giant tuna.
• Aquaculture ("fish farming") now accounts for 40% of the world?s fish consumption.
• Tuna ranching now takes place in every country on and in the Mediterranean, and in Australia and Mexico as well. It is scheduled to begin in Hawaii and Alaska.
• Because of commercial overfishing, almost exclusively to feed the insatiable Japanese sashimi market, all populations of bluefin tuna are endangered.
• Overfishing in the Mediterranean has caused such a drop in the bluefin tuna population that the World Wildlife Fund has called for a complete halt to all tuna-fishing there.
• If we cannot learn to breed bluefin tuna in captivity, the great fish will become extinct, writing finis to commercial and recreational tuna fishing--and to the consumption of maguro sashimi in Japan.
• In March, 2008, an Australian company called "Clean Seas" succeeded in getting captive bluefin tuna to spawn. If they can raise them to market size (200-300 pounds), it may relieve the pressure on wild-caught fish.