The Lower Depths : SONG FOR THE BLUE OCEAN: Encounters Along the World’s Coasts and Beneath the Seas.<i> By Carl Safina</i> .<i> Henry Holt: 458 pp., $30</i>

I hereby nominate Carl Safina as Official Informer. Not as a snitch but, rather, as the person whose job it will be to inform the rest of us about what’s really going on in the world. He is an ecologist with the soul of a poet: a writer of graceful prose on ungraceful, disturbing subjects.

Safina’s “Song for the Blue Ocean” is a heartbreaking requiem for the world’s aquatic resources. Is the extinction of the bluefin tuna, a creature that Safina lovingly describes as “half a ton of laminated muscle rocketing through the sea as fast as you drive your car,” the price we must all pay because some Japanese are willing to fork over $50 an ounce for sashimi? Are we going to lose the steelheads, Chinooks and coho salmon because local politicians are on the take from the lumber industry? Have we already lost 90% of the forests of the Pacific Northwest? Will we poison the exotic and distant coral reefs of the South Pacific?

When he flies over the Valley of the Giants in Oregon (named for the great evergreen forests), he sees “a far-and-wide landscape of mud, stumps, slash, bark and a few green sprigs . . . the land, forcibly stripped naked, the stump-studded hills standing in goose bumps, suffering from exposure. The cutters won’t willingly leave trees along the streams to keep the water cool and clean for salmon, but they will voluntarily leave trees along the roads, to fool us into complacency.” Your reaction to this is one of uncontrolled outrage: Wait a minute! Is this stuff really happening? How come nobody told me before?

Yes, “Song” is about wildlife and forests and deep blue oceans, but more than that, it is about people. People, after all, have turned pristine forests into scorched-earth, clear-cut disasters. People have dammed the Columbia, the Klamath, the Snake, the San Joaquin and the Sacramento rivers, making it impossible for the salmon to swim upstream to spawn. (“Fish ladders,” you ask, those devices designed to allow the fish to get upriver anyway? Forget it. The biggest dams, like the Grand Coulee and the Bonneville, have no such ladders.)

Nor is this a book about fish and trees versus the evil Army Corps of Engineers and Weyerhauser Co. (although sometimes you want it to be); it is a book that chronicles the legacy of those who struggled to retain their tenuous hold on the wonders of the world in the face of corporate greed, government corruption and bungling. People like Ed Chaney, who has devoted the last 30 years to a one-man crusade to save the salmon; Willow Burch, a 37-year-old part-Cherokee, part-Czech grandmother who lost her house and her livelihood when the salmon disappeared; Grandfather Oliver, 96, who says that “there seemed to be so many trees and so many fish. I didn’t see the end coming.”

People’s wastes have been allowed to leak into the crystal-clear waters of Palau to contaminate and kill the corals. The fish, some of them already endangered, are being hauled out of the water to be shipped--alive--to the market in Hong Kong, where, Safina estimates, 25 million fish are sold every year. (There is no way of estimating the number of fish that are killed in the collecting process or die en route, but probably only a small proportion make it to the market.) People eat the fish they catch in Palau and the Philippines. People spend lots of money for brightly colored reef fish to put in their home aquariums. Writes Safina of a trip to Dong-dong Island in the Philippines: “It has seemed more an expedition into the heart of a world apart than an outing to--of all things--catch aquarium fish for living rooms in the United States. I would not have guessed that such seemingly frivolous hobbies could have at their origin such deadly serious business a world away.”

In one sense, “Song for a Blue Ocean” is about the vast gulf between the haves and the have-nots of the world. Tuna fishermen (the have-nots of New England until they catch a giant tuna, at which point they are transformed into haves) hunt for plump tuna to sell to Japanese brokers so that Tokyo businessmen can pay $50 for a piece of toro the size of a Ritz cracker. Salmon fishers in the Pacific Northwest (have-nots) lost their fish and their livelihood because their predecessors fished out the resource, and the lumber companies and the farmers (who needed the water elsewhere) rerouted and dammed the rivers. Surely the most profoundly deprived of the people in question are the subsistence fishermen of Palau and the Philippines, who risk their lives (and kill off most of their inheritance of fish and corals) so that businessmen in Hong Kong, Taipei and Singapore can impress colleagues with their ability to pay a small fortune for a platter of lips from the Napoleon wrasse. (“Taking full-sized Napoleon wrasses off the reefs,” a biologist tells Safina, “is like killing tigers. And they suffer appallingly before they are killed, as do all these reef fish that are kept in crowded conditions.”)

And every one of these ecologically disastrous fisheries is being conducted in such a shortsighted way that no thought is given to the future; it’s catch the fish, take the money and the devil take the hindmost: “Rather than stewarding living, renewable ocean resources for continuity, long-term wealth and well-being,” Safina writes, “we have approached fishing more like mining. Because the animals are taken rather than manufactured, supplies of marine resources cannot be raised at will to meet demand, and attempts to force indefinite increases in supply by fishing more intensively can result in collapse.”

The decline and fall of the bluefin is bad enough, the destruction of the salmon and the rivers will make you cry, but nothing will prepare you for your visit to the fish market at Hong Kong. There are tanks filled with live, lovely reef fish. Unlike the Japanese, who prefer oceanic fish like tuna, the Chinese prefer the delicate flesh of reef fish, and they have to be able to see them alive before they eat them. And also, as Safina observes, “shark fins, shark fins, shark fins. Stall after store after shop, block after block, on both sides of the street. At any given moment, the fractional remains of hundreds of thousands of sharks are moving through these markets.”

As I was reading “Song,” I kept stopping to make notes, although I could hardly stop reading long enough to do so. The book is a page turner. But unlike the phantasmagorical novels of Michael Crichton or Peter Benchley (which are also page turners), where a little science is thrown in to give the plot an aura of verisimilitude, Safina’s book is all true and wilder and more frightening than anything those other guys could dream up on their best days.

Safina’s remarks are so prescient and powerful that it is difficult to focus on just one or two. But consider the following:

“I believe large parts of our oceans are depleted mainly because we treat marine creatures as commodities, forgetting that they are wild animals breeding in natural habitats. In reality, marine creatures are the only wild animals still hunted on a large scale. The language used in fisheries is a forced attempt to induce amnesia on this point. Fisheries people talk incessantly of ‘harvesting’ fishes, and even of ‘harvesting’ whales--trying to impart a sanitized and agricultural tone, as though hunting the largest creature ever to live on Earth by firing bombs into their bodies is analogous to picking watermelons that have been planted and cultivated. Fish populations are referred to as ‘stock,’ like shoes in a warehouse.”

I once thought about writing a book about the depletion and destruction of the oceans. Safina has done what I could only dream about: He has written a plaintive, sensitive, caring, intelligent, indignant paean to his beloved waters and their threatened inhabitants. His book will make you mad as hell; it will make you marvel at the wonders he describes (his descriptions of bluefin tuna, like the great fish themselves, are poetry), and it will make you glad there is someone like him to devote his life to the preservation of the Earth’s most fragile and misunderstood ecosystems.

Rachel Carson wrote several books about the sea, including the award-winning “The Sea Around Us.” When she wrote “Silent Spring” in 1962, she told us about things few people suspected. The spread of DDT and its deleterious effects on living things, other than insects, came as a frightening revelation and changed the way we thought about our interaction with nature. We all know something about what’s going on off the coast of New England or in the Pacific Northwest, but I’ll venture a guess that few people are aware of the cyanide poisoning of the reef fish of Micronesia or the exotic eating habits of some Chinese capitalists.

I realize that everyone invokes “Silent Spring” when they review a new book about the deteriorating environment, but I’m going to risk the cliche and tell you that Safina’s “Song” is the “Silent Spring” for our time. It should be a clarion call for people who think that creatures of the depths (or the shallows) are safe from the voracious predations of fishermen. I loved this book, but I hated what it was about. It was like reading a brilliant description of Auschwitz or Hiroshima. It is a frightening, important book. Read it and weep.