American Catch reveals how U.S. seafood tastes drifted far from home.

You get the idea Paul Greenberg is accepting a dare when he puts on scuba gear and dives into the waters of Jamaica Bay – right at the filthy confluence of Brooklyn, Queens and JFK International Airport. He doesn’t find the naturally spawned New York City oyster he’s looking for that day, but he chances on one later, while wearing hip waders. And he follows through.

“I stared into the still-beating heart of the oyster and felt something strange: a mixed-up muddy feeling as murky as the Bronx River at my feet… A city official standing nearby whose many overtaxed duties probably included preventing New Yorkers from eating local oysters raised her eyebrows high and emitted a tiny gasp… It was delicious, if a bit warm.”

The dangerousness of this act, eating a wild oyster from NYC’s polluted waters, is part of the point in American Catch: The Fight for our Local Seafood. In it, Greenberg – presenting himself as part egghead, part guy at the bar – adventures through America’s changing relationships with three harvests from its own shores. His case studies pan from dismal to hopeful, following the Western migration of American industrialization, pondering this riddle: The U.S. imports 91 percent of the seafood we eat and exports one-third of the seafood we catch.

The market for New York’s native oyster has risen and fallen with the health of its estuaries. In the late 1800s, Greenberg writes, it was so booming, the U.S. exported 100,000 barrels of wild oysters a year to England. Now, good luck finding just one in NYC’s toxic, built-out waters. And that one might give you hepatitis.

A little less claustrophobic in the Gulf of Mexico, Greenberg spends time with the Louisiana brown shrimp. The humble crustacean should be the star in a country whose hunger for shrimp tops all the other seafoods – yet the U.S. imports almost all of our shrimp from Asia.

Greenberg parses the market forces at work here in unappetizing terms. Stock brokers see shrimp as a predictable commodity, with unwavering American demand. Asian shrimp farms pump it out using cheap labor and intensive methods. Processors freeze it, treat it with tripolyphosphates and ship it across the Pacific to arrive in the U.S. gummy and gray, destined for all-you-can-eat buffets, while both estuaries and shrimper families are disappearing in Louisiana.

“In becoming Asia’s premier market for shrimp,” Greenberg writes, “the United States has effectively unhitched itself from its own seafood supplies and hollowed out its ability and rationale to protect its own marine resources.”

By this point in the book, I’m thirsty for waters that haven’t been ravaged. He delivers it with Alaska, America’s last frontier: “The Bristol Bay sockeye salmon grounds are an untrammeled latticework of rivers, ponds and lakes that can generate more than 200 million pounds of fish per year.”

Weirdly, the U.S. exports almost four-fifths of that Alaskan salmon catch, he writes. Even weirder, we import two-thirds of the salmon we eat. Then he delivers his gut hook: the proposed Pebble Mine, which would be the biggest copper and gold mine in North America, threatens the last healthy domestic seafood industry America has left. (President Barack Obama blocked oil drilling in Bristol Bay in an executive order Dec. 16, but the Pebble Mine is still on the table.)

It’s not shocking that the U.S. imports and exports seafood. But Greenberg reveals our new normal – this bag of de-veined whiteleg shrimp at Costco is from Thailand, shrug – as seriously bizarre. He’s flagging the disconnect. We’ve lost motivation to protect the habitats that sustain our own American seafood supply. With it we’ve lost fishing jobs, local food cultures and our health.

“There is no more intimate relationship we can have with our environment than to eat from it,” Greenberg writes. “Over the course of the last hundred years that intimacy has been lost, and with it our pathway to the most healthful of American foods. It is, in my opinion, our obligation to reclaim this intimacy and build a bridge from the plate back to the estuary. This requires us not just to eat local seafood. It requires the establishment of a working relationship with salt marshes, oyster beds, the natural flow of water from river to sea, and the integrity of the ocean floor.”

In American Catch, Greenberg sticks with the formula that worked for his last book, Four Fish, which is sectioned into salmon, sea bass, cod and tuna. American Catch adds to the growing genre of literary food nonfiction spiked with science, history and culture – in the vein of Michael Pollan’s Omnivore’s Dilemma and Barbara Kingsolver’s Animal, Vegetable, Miracle.

Like an artfully prepared dinner, Greenberg’s latest is best digested slowly. It’s written simply enough, but packed with insights worth holding.

Not all of those insights are appetizing. But Greenberg challenges us to take the dare.

American Catch: The Fight for our Local Seafood. The Penguin Press, July 2014. $26.95/hardcover. www.paulgreenberg.org; @4fishgreenberg on Twitter.