I SPENT THE winter of 1998 in Moscow. Daylight was a precious commodity that seemed to be gone as soon as I was awake enough to appreciate it. Hours were used up underground, breathing in the yeasty fumes of the subway's beery denizens. The fog in my head only seemed to clear when I would stand beside one of the city's shiplike, onion-dome churches, whose bells would peal out so loudly that I would experience sympathetic vibrations. Lina, a family friend, was a rare bright spot on the landscape of my days. She inevitably met me at the door of her book-lined apartment with a pair of slippers and the inquiry "Masha, screw?" By which she meant to ask whether I would like a screwdriver. I'd drink, and we'd smoke, and she'd feed me. She introduced me to the flavor of farshmak – chopped herring, egg, and apple salad – and I always looked forward to an endless supply of krasnaya ikra: red caviar. A purist, or a bureaucrat, would say this fatty and protein-rich delicacy – familiar to sushi lovers as ikura, salted salmon roe – isn't entitled to the caviar moniker. Under the rules of international labeling, only sturgeon roe can be called caviar.

This distinction may soon be moot, however, because the sturgeon, which has been around for 180 million years, was recently dealt a nasty blow. On Oct. 21 the U.S. Fish and Wildlife Service declared that although the beluga sturgeon was being placed on the threatened species list, the importation of beluga caviar would continue unimpeded while the service decides how to regulate it. The outlook is bleak for the sturgeon family. The world's beluga sturgeon population has declined by more than 90 percent over the past two decades, and "its numbers dropped nearly 40 percent" in one year (2001 to 2002). The United States accounts for the majority (60 percent in recent years) of the world's beluga caviar consumption. These figures are cited by Caviar Emptor, a campaign that aims to preserve the threatened Caspian sturgeon (www.caviaremptor.org).

The Caspian Sea is the earth's biggest salt lake. Along with its more than 100 tributaries, it's home to most of the sturgeon varieties that produce the most valuable caviars: beluga, sevruga, and osetra. Iran and four countries formerly of the Soviet Union – Russia, Kazakhstan, Turkmenistan, and Azerbaijan – border the Caspian. Regulation of the fishing and caviar trade has weakened in the onetime Soviet countries, and the illegal sturgeon catch greatly exceeds the legal one. No wonder; Caspian beluga caviar sells for more than $100 an ounce. Besides overfishing and poaching, pollution is a major problem. Sturgeon take up to 20 years to mature and spawn and may live to be more than 100 years old and grow to 2,000 pounds. Their lengthy life cycle makes them especially vulnerable to pollution's effects.

Accounts differ as to how and when caviar became so prized. Certainly, people have been eating roe for as long as we've been eating fish. (The difference between just plain roe and caviar, incidentally, is that caviar is salted or brined for preservation and taste. Borax is also sometimes used in the preservation process, but borax-preserved caviar is apparently not importable to the United States.) Caviar purportedly became all the rage in the 1920s in French society, when an influx of Russian nobles fleeing the Russian Revolution made the French, briefly, Russophiles. The Petrossian family, still big in the caviar business, introduced French society to this delicacy, which was initially dismissed but then caught on – whether because people actually liked the taste or because they wanted to be chic, it's hard to say. The United States experienced a caviar craze in the late 19th century that led to the extreme depletion of indigenous Atlantic and white sturgeon, to the point where the sturgeon fisheries on both coasts had to be closed. During the craze, caviar was sold as a salty snack at concession stands, like popcorn, to encourage people to buy more beer.

The wild sturgeon population of the United States has yet to recover from that, and other, onslaughts. Caviar from wild domestic sturgeon and paddlefish (a close relation) is available, but as with other fish, some states have issued consumption advisories for paddlefish and sturgeon from certain waters because of the high levels of mercury and other chemicals in them. However, sturgeon farming has caught on since the first successful (U.S.) experiments with it at UC Davis in the late 1970s. (Caesarean sections to remove roe from the precious sturgeon without killing them are being experimented with both in the wild and on the farm.) California and Missouri produce most of the United States' farmed caviar. Tsar Nicoulai Caviar – which has a restaurant in the Ferry Building – produces some widely respected caviar on environmentally sustainable aquaculture farms; Stolt Sea Farm (producer of Sterling Caviar) is the other major caviar farm in California. Any real caviar lover – except one who only enjoys the prestige, not the taste – will be delighted with the flavors from these farms. Wild sturgeon have been around since the dinosaurs and are in danger of meeting the fate of the dodo. Buying farmed sturgeon caviar is, at this point, the only responsible consumer choice.

E-mail Masha Gutkin at lydialeapfrog@yahoo.com.