Hors d'oeuvres at expensive functions often serve caviar spread on bread or crackers. This combination is a favorite with champagne at wedding receptions. There is a hierarchy with different varieties being valued above others. The Beluga kind is very expensive as is Ossetra and Seruga. The Beluga Sturgeon however, is on the list of endangered species and the US has now banned the black caviar from that source found in the Caspian Sea and the Black Sea.
Other sources are in danger of extinction, due to polluted waters and over fishing. One of the most popular varieties, favored by the world's rulers of the past is the Sterlet. This fish that produces golden colored caviar is in great danger of disappearing from our seas. The US and Canada used to have a thriving industry, competing with caviar producing nations such as Russia and Iran, but their yields have decreased and one of their primary sources, the Shortnose Sturgeon is also endangered.
In order to combat the problem of a decrease in the traditional supply lines, producers have looked to Whitefish and North Atlantic Salmon roe to process. Paddlefish and Hackleback are other alternatives. It may not be the high point but it does make the delicacy more affordable for everyday people. Of course, it's not to everyone's taste, having such a strong, distinctive flavor. Those that do like it and are used to having it can be rather snobbish about where it comes from and how much was paid for it and so on.
The other means of keeping the trade going has been an
increase in Aquaculture, otherwise known as Sturgeon farms,
where the fish are commercially cultivated in similar fashion
to the Trout and Salmon farms we are more familiar with. This
cheaper method of production has proved successful in France,
South America and the US. There isn't the same kind of
attention placed on the fate of the Sturgeon in Scandinavian
countries. They have been perfectly content for years with
their smoked cod roe. In fact Finland is renowned for its
Burbot caviar, which some gourmets claim to be the highest
quality of them all, beating the Sturgeon for taste and
cost.