10 20 40 60 cm
mittakaava < 40 cm
Gösta Sundman: Suomen Kalat (Kansalliskirjasto, The National Library of Finland), Lauri Urho
Clupea harengus membras
- Family: Herrings – Clupeidae
- Similar species: sprat, twaite shad
- Size: Usually 15–20 cm, fast-growing giant forms may exceed 30 cm and weigh 0.5 kg.
- Appearance: In common with other members of the herring family the lateral line is absent. Scales easily detached. Snout slightly longer and more angular than in the sprat, giving the Baltic herring a somewhat less streamlined appearance. Both species have a ridge of scutes (rough or sharp scales) along the belly, and these are easily felt by running the finger along from tail to head. These scales are noticeably sharper on the sprat than the Baltic herring. Size is also a good guide: individuals over 17 cm are almost certainly Baltic herring. However, the two are best distinguished by the position of the pelvic fins, which are level with, or slightly in front of, the origin of the dorsal fin in the sprat but further back in the Baltic herring. The giant form of Baltic herring might be confused with the far less common twaite shad. However, the Baltic herring has sharper scales along the belly and lacks the ridged gill cover of the twaite shad.
- Colouring: Sides silvery, back dark on top, greenish lower down. The back of the sprat is more bluish. Giant Baltic herring lack the row of dark spots that characterise the twaite shad.
- Reproduction: Baltic herring spawn from spring through to autumn. Fewer fish spawn in the autumn, although following a mild winter these populations increase thanks to greater fry survival. Eggs usually laid on hard sea bed along ridges; muddy bottoms are not favoured.
- Food: Plankton, larger fish feeding on planktonic crustaceans and even small fish fry.
- Distribution and habitat: Common throughout Finland’s seas. Large shoals of Baltic herring roam open waters in search of plankton and other food. Feeds close to the surface at night and seeks deeper water by day. Found inshore in spring but as summer progresses Baltic herring move out to sea, where they spend the winter.
Finland’s most commercially exploited species, although its popularity as a food fish has declined in recent years. Nevertheless, a delicious fish that can be prepared in numerous ways.