Salaca [1] [2] , or Baltic herring [1] ( lat. Clupea harengus membras ) is a Baltic subspecies of Atlantic herring from the herring family. Length up to 20 cm, weighs 25-50 g. It lives in the Baltic Sea, in its freshwater Curonian and Kaliningrad bays and the fresh waters of some Swedish lakes [3] .
| Sprat |
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| Scientific classification |
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| No rank : | Bilateral symmetric |
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| International Scientific Name |
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Clupea harengus membras
Linnaeus , 1761 |
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Content
The length of the small head is 23.4–25.9% of the body length. The diameter of the large eyes is 24.7–28.7% of the length of the head. The mouth is medium; the end of the upper jaw comes to the middle of the eye; there are well developed vomer teeth. The belly is rounded with a weakly expressed keel formed by 9–15 scales. In the dorsal fin there are 17-21 rays (on average, 19, the first 3-4 rays are not branched); anal fin 15-19 (on average 17, the first 3 rays are unbranched); on the 1st gill arch 60-71 (on average, 66) stamens; vertebrae 54–57 (55 on average). The dorsal surface is dark blue, the sides are lighter, the belly is silvery white [4] .
It feeds on small crustaceans. Always keeps school, mainly in the upper layers of water ( pelagic fish). Sexual maturity occurs in herring around the age of two or three years. Lives up to 11 years. The bulk in the catches are individuals aged between two and four years, 14-16 cm long. Salak forms local herds confined to separate parts of the sea and to the bays, as well as "seasonal" races that differ in terms of spawning. There are two races: spring and autumn [5] . The spring race of the herring spawns in May and June at a depth of 5-7 m; ground roe. The autumn race is small, spawns in August - September, far from the coast. For the autumn race, a large-eyed and low-eyed form is noted. In addition to the usual, small (up to 20 cm), forms there are giant herring up to 37.5 cm (Riesenstromlinge - from the Germans, jättesströmmingar - from the Swedes and silli from the Finns), which belong to the same Baltic subspecies, but are a special, rapidly growing race [6] . The spring sprat of the Gulf of Riga population becomes mature at about two years of age, and the autumn sprat at 2-3 years old. The sea spring herring of the eastern coast and the Baltic herring of the Gulf of Finland spawns for the first time at 3 years, and the sea autumn herring at 3–4 years. In the south and west, the sprat reaches sexual maturity at the age of 2-3 years [4] .
The fecundity of spring herring from the eastern part of the Gulf of Finland averages 10.6 thousand eggs [6] . The life span of the Baltic herring in the Baltic Sea from south to north is increasing. The age of the oldest individuals in the northern part of the Baltic reaches 19 years [4] .
The fish are dominated by fish 2–4 years old, 12–17 cm long in the north, 15–20 cm in the central part of the east coast, and 18–22 cm in the south [4] .
Power
The main food in the fall, winter and spring are the copepods Limnocalanus and Eurytemora . In July - August and the beginning of September (in the Luga and Koporskaya lips), Bosmina and Daphnia branchy crustaceans take the first place in the herring feeding. Giant herring eats stickies [6] . The sprat or sprat ( Sprattus sprattus balticus ) is a competitor in the diet of the sprat, which feeds mainly on the sprat.
Caviar and sprat larvae serve as food for colegrass and beldyug , young sprat eats cod , salmon ; the adult herring may be the target of a lamprey [4] .
Migrations
Sprat periodically comes from open areas of the sea to the coastal zone and moves back. In the spring comes to the shores on small places or keeps in the surface horizons. In summer, when the water at shallow places and in the surface horizons warms up to 16 ° C, the sprat leaves into the open areas to deep places and stays in the middle horizons. In the beginning of autumn, with the cooling of the surface layers of water, it rises again to the upper layers and goes to the shallow waters. At the end of autumn, with the onset of a strong cooling of the water, the Baltic herring again departs to deep places and remains in the bottom layers of water.
Harvest all year round. They catch with nets (fixed and smooth), traps (least horn stabbing and fixed nets) and inceptive nets.
About half of the total catch is used for cooking canned food (“sprats in oil”) and preserves (“kilka” and “anchovy”). By means of a special (half-hot) smoking, smoked herring is known, known as “smoked”. Part of the catch is realized in chilled or frozen form [6] . Salak is salted, smoked, fried in butter and baked in sour cream and with dill, it is a national Finnish dish [7] .
