You expect me to eat that?

When French King Louis XV first tasted caviar, he found the flavor so revolting he spat his mouthful onto the rug of the Versailles palace. Despite similar reception across 18th-century Europe, caviar savored of Russian opulence, and it soon became a coveted symbol of status throughout the region, and later in America.

In her new book, "Caviar," Inga Saffron explores the colorful history surrounding this unlikely delicacy of salted sturgeon roe. Saffron charts the sturgeon's course from river-bulging abundance to near extinction, along with the mystique and legend that enabled Russian, German, and French barons to cash in on its black gold.

Caviar first gained popularity in medieval Russia, where Orthodox Christians were required to avoid meat for as many as 200 days a year. Russians became avid eaters of fish, and caviar became a sort of national dish among poor and rich alike.

With their pointy, armor-like plates, the massive sturgeon were harder to net than most fish, and thus caviar was always a precious commodity. While connoisseurs have savored the succulent eggs for millenniums, the Industrial Revolution brought a turning point. Technological advances made it possible to catch the fish and transport its freshly salted roe over long distances. And more important, a new middle class grew hungry for symbols of its newfound wealth. Caviar fit the bill. The biggest market is now composed of Americans, whose '90s wealth generated record demand for luxuries.

There is a certain irony to the story of the sturgeon. This lumbering beast has existed unchanged for 250 million years, surviving where dinosaurs did not. And yet, in the space of two centuries, it has come snout to snout with near-extinction. Despite its Dar- winian success, the sturgeon may not easily face down the mass market.

Sturgeon are saltwater fish that swim up freshwater rivers to spawn. There are 27 species, which can be found along the coasts of the Caspian, Black, Adriatic, and Mediterranean seas, and in the Atlantic and Pacific. Fishing has exhausted most populations, and the last remaining few can be found along the Volga in Russia.

"Caviar" traces how an ex-patriot Russian scientist and his American counterpart put sturgeon on the international list of endangered species – and the drama that got the Russian scientist kicked out of the scientific community.

Saffron also explores the slimy underbelly of the caviar black market. With the collapse of the Soviet Union and its tight controls, it's been open season along the banks of the Volga, where cash-desperate poachers harvest many times the legal catch each year. Their work feeds a strong black-market trade, and odds are good that off-the-shelf caviar was made in one of their illicit fishing shacks.

Within a year of international quotas being enacted in 1998, the black market rendered caviar as valuable as cocaine. That year, two smuggling rings brought to the US about 10 tons of caviar – more than Russia's entire legal quota. Several crime rings have since been broken, but the illicit trade remains lucrative.

There may yet be hope for this prehistoric fish, however. Iran's Caspian sturgeon industry is the only one to replace the captured sturgeon with an equal number of juveniles, setting a model for other nations. And two sturgeon farms in France and the US are betting that the future market will be for "sustainable," farm-raised caviar.

While "Caviar" sometimes plods through statistical sediment, Saffron's careful research is a fitting tribute to this dwindling species. A former Moscow correspondent for the Philadelphia Inquirer, Saffron writes with color and flair. It's almost enough to make caviar sound tasty.

• Julie Finnin-Day is a freelance writer currently traveling in Vietnam.