Herring is a pelagic fish that lives in large shoals and migrates along the coast and out to sea, down to depths of 200 metres. There are two main populations of herring: Northeast Atlantic herring (i.e. Norwegian spring-spawning herring) and North Sea herring. They are categorized according to where and when they spawn, their size, their growth and how they migrate.
Norwegian spring-spawning herring is the largest population. It spawns in February and March, at the bottom of the sea along the coast of Norway. The eggs hatch after about three weeks and the larvae drift with the current northwards into the Barents Sea. After three to four years, the herring leaves the Barents Sea and migrates southward to join the spawning stock. Herring is an important prey for cod, saithe, sea birds and whales, and large numbers of killer whales follow the herring during migration.
The fat content of Norwegian spring-spawning herring varies throughout the year, but it is at its highest in the autumn. Herring lives up to 25 years.
Fishing of herring takes place mainly between October and March, when it is easily caught and the quality is the best. Common equipment used is purse seine, pelagic trawl and net.
Sold as frozen fillets or as whole frozen fish. Norwegian herring are graded and sold by size. The most common size categories are: under 200 g, 200–300 g, 250+ g, 300+ g, 350+ g, 400+ g, and 1 kilo.
Herring is especially rich in:
- Protein that builds and maintains every cell in the body.
- Marine omega-3 fatty acids that prevent and reduce the development of cardiovascular diseases, and are important building blocks in the brain.
- Vitamin D, necessary to balance calcium in the body, which maintains and strengthens the bones.
- Selenium, an important element in an enzyme that fights harmful chemical processes in the body.
More nutritional data can be found at www.nifes.no/en/prosjekt/seafood-data