“Roe is the fully ripened internal egg masses in the ovaries, or the released external egg masses of fish and certain marine animals”. The Wikipedia definition of roe makes it seem more suited to a zoology textbook. But many cultures around the world consume some form of fish roe. It is weirdly, a universal culinary delicacy. This week, let’s take a trip around the world exploring a variety of fish roes, beginning at home.

It is peak ilish season now, when huge numbers of the fish are caught, during the monsoon months of July to October, which coincides with the upstream journey of the fish. A simple meal of rice with a piece of fried ilish is nothing but pure heaven. It is a fatty, flavourful fish which can be fried, steamed or made into a light curry. The fat lends it that distinctive flavour that makes Bengalis swoon.

In an attempt to save the ilish population, which is facing extinction due to overfishing, attempts are made to avoid catching and selling juvenile fish, which do not bring as much money and also prevent these fish from spawning, a lose-lose situation. Also, no fish should be caught at all during the major spawning season during October and November.

If you do spot an egg sac full of roe in a mature fish, it’s fine because a mature fish above 500 gms or 25 cm length has most definitely undergone at least one breeding season. Ilish roe has an interesting texture, but the main reason we love it is that unmistakable flavour that permeates the entire fish. It can be fried as it is and eaten with rice, or can be mashed and made into fritters (machh-er dim-er bora).

Although many attempts have been made, any attempts to farm ilish have been unsuccessful so far. However, another very popular fish which follows a similar life cycle of a marine life with an upward journey to the rivers during the breeding season, with a fatty and distinctive flavour and highly prized roe, has been farmed very successfully. Salmon.

Salmon roe is usually salt-cured before consumption and unlike that of the ilish, are much larger with a bright orange-red colour. Another major difference is that salmon roe is usually consumed raw (unless you count the curing process as “cooking”, which it really isn’t). It explodes in the mouth with a briny pop, which makes it excellent for folding into scrambled eggs or slathered over a buttered piece of toast.

Japanese called cured salmon roe ikuri, and is commonly used in sushi. Another common example is tobiko or flying fish roe. They are much smaller than salmon roe with the same reddish-orange hue, although roe dyed green (with wasabi, for example) or black (with squid ink) are also common. Like ikuri, tobiko adds a vibrant colour and a briny pop. But since they are so small, the mouthfeel is entirely different.

There is actually a huge number of fish roes used in Japanese cuisine. There’s Masago, the roe of Smelt or Capelin, a fish from the Arctic and Atlantic, which is even smaller than tobiko. And then there’s uni, the yellow, tongue-like gonad of the sea urchin that produces the roe. It supposedly has a creamy, custardy texture with an unmistakable flavour of the sea, and is commonly eaten raw as sushi or sashimi, or even stirred into pasta.

Mentaiko spaghetti is a classic Tokyo pasta, made with spicy marinated pollock roe. And then there’s the karasumi, made by salting the entire egg sac of the mullet and drying it in sunlight. Karasumi is very similar to Italian bottarga, also made using mullet and christened the “Prosciutto of the Sea”. Bottarga can be used to finish pasta dishes, grated over the dish in the very end to add a fishy boost adored by seafood lovers. It is incredibly intense, so tread lightly.

Which brings us, finally, to the Rolls Royce of fish roe. Although the salted roe of any fish can be called caviar, the term is used specifically for the roe of the sturgeon which like the hilsa, salmon and capelin is also an anadromous fish, meaning it moves upstream to spawn. But, why is sturgeon caviar so expensive?

It is based on an economic concept called the rarity value thesis, which states that a product becomes more valuable if it becomes rare, even if the product itself remains the same. This is why champagne and traditional balsamic vinegar, which can only be produced in specific geographical regions, or truffles, which need to be sniffed up by dogs, are so expensive.

There are a lot of fish in the sea, and many of them produce stunning roes with the same briny pop. What makes sturgeon caviar so much better? Well, patrons claim that the flavour of Russian beluga caviar is beyond comparison and well worth the exorbitant price. I haven’t tried caviar myself so I’ll have to take them at their word.

In any case, this increasing demand for caviar among the elite has led to overfishing with a critical endangering of the sturgeon population. It is the same issue as the one we have with the ilish back home. Caviar making is a labour-intensive process as it is. Add to that the dwindling sturgeon population and the price skyrockets. This makes caviar inaccessible for most, but this rarity makes it even more lucrative to the people who can afford it, and this increase in demand causes even more fishing, thus initiating a vicious cycle that is slowly pushing the sturgeons towards extinction.

Eighty five percent of sturgeon is at risk of extinction, making it one of the most threatened animal groups on the IUCN Red List of Threatened Species. And it is our responsibility to remedy this situation. Be it the hilsa back home or the Russian beluga sturgeon, a level of moderation is mandatory to prevent these species from becoming extinct.

An increase in demand leading to an overexploitation of a lot of natural resources, including these fish whose roe is so prized. As I’ve already said, fish roe is a universal culinary delicacy, and it is up to us to ensure moderation so that things don’t get too out of hand. Enjoy your ilish machh er dim, but make sure there’s some left over for posterity.