Caviar is a delicacy consisting of salt-cured roe of the Acipenseridae family. Caviar is one of the most expensive foods in the world, selling for up to $35,000 per kilo, it's revered and relished by aristocrats around the globe. Caviar was not expensive in the 19th century even it was served for free in saloons, like bar nuts. In Europe during 19th century fisherman used to leave them on the beach to spoil.
Why did there was increase in the price of caviar? Actually caviar doesn't come from just anywhere. To get the real thing it has to be egg from a sturgeon. There are 27 species around the world, in North America , Europe and Asia but probably not for long.
In 2010, the International Union for Conservation of Nature placed 18 species of sturgeon on its red list for threatened species, making the sturgeon the most endangered group of species on earth. This effort helps to protect the endangered sturgeon species as it is illegal to fish them in many places in the U.S. Because of this ban caviar become more rare in the world. There is a thesis called "Rarity Value" Thesis and it describes how the rarity increases the value of the item.
There were some reasons behind the rarity of the sturgeon. Increase in pollution and more number of dams blocked them from spawning ground upstream. They had nowhere to reproduce and continued to be over fished for there meat and roe. On top of that, it takes eight to twenty years for a female to sexually mature depending upon the species.
Image 1 Source : https://www.markys.com/Caviar/
Image 2 Source : https://www.petrossian.com/petrossian-original-pressed-caviar