Why eels are not bred in captivity? It's all about the great mystery of their reproduction (9 photos)

Do you think this problem doesn't affect you? Now remember how often you order sushi? Here! And if eels die out, what will you eat for the holidays? So let's take the topic of eel sex life more seriously!





Today it's yuck, but tomorrow you'll be ordering sushi with me!

First, let's define the essence of the problem. Eels do not reproduce in captivity, but why does everyone care so much? The fact is that eels are an important commercial species. If you don't eat it every day, it doesn't mean anything: the world production of this fish is comparable to herring - the most common table fish in the CIS. Over 300,000 tons per year, mind you!

But herring doesn't reproduce in captivity either, so why are people so alarmed?



Vermicelli with milk, delicious, a favorite food from childhood! Or did I mix something up?

The herring population, unlike the eel, is not going to die out yet. But the most common and widely harvested of the 23 species of eels: American, European and Japanese eels are now on the verge of extinction. Therefore, it is critically important to establish a full cycle of breeding fish in captivity.





Breeding eels is difficult, growing them is also difficult, but keeping adults is quite easy. And all thanks to the fact that the fish are tolerant of their relatives and can live in such a snake-like lump without harm to their health and others.

But it is not possible to establish this reproduction. And all because of the tricky way of reproduction. During its life, the eel goes through 4 stages of maturation. The first is the larva, or leptocephalus. A microscopic fry that chatters at the level of plankton, it looks like a creepy fish ghost. Transparent body, needle-like teeth and an unblinking gaze that pierces through.



You don't need a fisherman here, but a ghost hunter!

The second stage is the glass eel. During this period, the young more or less become like a fish. The fry rushes from the sea to the rivers - eels grow exclusively in fresh water. At this stage, companies catch eels for farms.



Well, at this stage the eels don't look very appetizing...

The fish are put in pools and fed intensively so that they quickly reach the third stage - yellow eels. This is the same eel that we see on the shelves. A lethal amount of calories do their job: the fish gain the required weight in just a year!



A typical lunch break in a school cafeteria.

It is pointless to keep eels any longer. This is because it is almost impossible to achieve their spawning in captivity. For reproduction, the final stage must come - the silver eel. In the natural environment, fish mature to it from 5 to 20 years. And then - goes on a long journey. European populations reproduce in the Sargasso Sea. And it is located, by the way, off the coast of North America. It turns out that eels swim across the Atlantic and cover from 5,000 to 7,000 km!



Visual migration map. The eel's path is not short!

Technically, adult eels can be injected with hormones, forced to swim in a fish simulator, and played with the salinity of their aquarium. After such a quest, the eels will have mature eggs and milt, and they will even want to spawn. It's long and expensive, but it can be done. But people haven't figured out what to do with the first-stage larvae, the leptocephali, yet.



I'm not only scary, but also terribly picky!

In one experiment, scientists managed to keep a population of newborn eels alive for almost a year, but to no avail - in the wild, leptocephali move on to the second stage of development after six months and turn into glass eels. And in aquariums, the eels eat poorly, suffer and die, no growth.



And with such a look, it seems that he eats the souls of sinners.

The main reason for the death of young eels is improper nutrition. In the ocean, the larvae feed on sea snow - a kind of hodgepodge of plankton, crumbs of carrion, algae and other garbage that floats in the water and gradually settles down. In the conditions of an aquafarm, it is almost impossible to make such a snowball. So it turns out that due to all these difficulties, today eels cannot effectively reproduce the population of their own kind. At the same time, the demand for fish meat does not go away! Farms catch wild eels irrevocably, which is why the population of the species is slowly but surely declining.