The diversity of the inhabitants of the oceans is so great that not all representatives of the underwater world have yet been studied and described in detail. But there are fish, with the name of which, everyone immediately represents canned fish or preserves. We are talking about everyone’s favorite sprat. It is believed that the sprat owes its name to the ship’s keel, which it resembles in its appearance, in particular, its oblong abdomen.
The sprat belongs to the herring family and under its name combines two types of fish: kilka and sprats. The body of the sprat is elongated with a wide back and compressed sides. The abdomen is rounded with distinct keel scales. The head is elongated and wide with small eyes, with the exception of — big-eyed sprat. The mouth is small. The caudal and dorsal fins are dark, the rest are colorless.
A special feature of the sprat is its small size and silver scales. On average, the sprat reaches 10-12 centimeters. The largest size is fixed at 17 centimeters. Females are larger than males. Each fish weighs no more than 45 grams. The sprat scales are smooth and shiny. The dark back turns into silvery sides and an almost white belly. This coloration of the scales makes it invisible in the water, from above from birds, from below from other fish.
The sprat lives mainly in the salty waters of the seas, but can also enter the deltas of freshwater rivers. In 1930, the Abrau kilka, which lives in freshwater lakes, was first studied and described. It got its name from the name of Lake Abrau near Novorossiysk, where it was first classified. Its close species is common in the freshwater lakes of Turkey. But still, sprat, first of all, is considered a marine fish.
The distribution area of the sprat can be determined only by the names of its species, tied to the names of the seas: Caspian, Baltic, Black Sea and Arabian. It should be noted that the kilka population in the northern seas of Russia and Europe is larger than in the southern seas. Most likely, this is due to the fact that the southern continental seas are more isolated from the general system of the World Ocean. Accordingly, there is less food.
The nutrition of sprat in salty seas and freshwater lakes is no different. It feeds on plankton, which, in addition to unicellular algae, includes protozoa, crustaceans, and fry and eggs of other fish. In the Baltic Sea, there is competition between sprat and herring for plankton. It has long been noted that if the sprat population increases, then the herring in the sea becomes scarce, and vice versa.
It is difficult to imagine the nature of the fish, but if you look closely at their behavior, you can notice some features. For example, if we compare sprat with melancholic stingrays, sanguine sharks or phlegmatic flounders, we get that sprat is choleric. The sprat is small and fidgety with a short lifespan. She needs time to play, grow up, leave offspring and dodge all her enemies.
Sprat — schooling fish. Approaching the shore, the flocks unite into huge shoals. The fish move so fast and erratically that it looks like the water is boiling when they come close to the surface. Then, just as suddenly, the sprat goes back to the open sea, preferring to stay at a depth of 6 to 30 meters. The deepest subspecies is the big-eyed sprat. She prefers a depth of 70 to 200 meters.
Sprat lives on average up to 5 years. The ability to reproduce appears already in the second year of life. It breeds from April to October, depending on the species. Spawning takes place in portions, both in shallow water and far from the coast. During the spawning period, the sprat lays pelagic eggs, that is, the eggs float on the surface or in the water column. Each female sprat produces from 6 to 14 thousand eggs.
Eggs about 1 mm in size develop over 1-3 days in the same pelagic zone. The larval stage lasts up to six months. During this time, an insignificant part of the larvae turns into fry. Fry grow in coastal zones at a depth of 2-3 meters, feed on rotifers and larvae of molluscs and crustaceans. As they develop, the fry eventually go to great depths and further from the coast.
In nature, the sprat is very fond of marine mammals, birds and large fish of other species. Its main consumers are seals, dolphins, gulls, sturgeons, herring and zander. The sprat is saved only by its agility and the protective color of the scales. An interesting discovery was made by archaeologists at the University of Michigan. When examining the fossilized remains of fish, they found that in the era of dinosaurs, the sprat was a predator and was 1 meter in size.
The sprat is a popular commercial fish in many countries. The annual catch is up to 600 thousand tons. But despite this, the kilka population is stably kept at a high level. Scientists closely monitor the seasonal migrations of large schools and continue to argue over the allocation of some subspecies of sprat to separate species. For example, the Abrau kilka is presented in many publications as an independent species.