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Herring

size

up to 45 centimeters

weight

up to 1050 grams

color

back: dark blue; flanks: silver-gray

lifespan

up to 25 years

food

zooplankton and fish larvae

reproduction

lays eggs

  • Dut: Haring (bankharing, bliek, doggerharing, kanaalharing, zuiderzeeharing, noordharing, Noorse haring, Noordzee haring, IJslandse haring, Baltische haring, Buchanharing, Downsharing, Røgenharing)
  • Lat: Clupea harengus
  • Eng: Herring
  • Ger: Hering
  • Fren: Hareng
  • Dan: Sild
Herring, Joachim S. Müller, via Flickr

Herring

Herring live in enormous schools, sometimes containing millions of fish. They swim at deep depths during the day. In the evening, they follow their prey closer to the surface and disperse just under the water surface for the night. Herring feed on animal plankton. As they swim, they sift these small animals out of the water with the help of filters located on the inside of their gills. The filter is made up of long 'thorns' which are situated as a comb on the gills. In turn, herring are a main source of food for predator fish, seals, cetaceans and sea birds. They play a key role in the North Sea ecosystem.

  • Various populations

    There are three groups of herring in the North Sea, each group laying its eggs at different places and at different times. One group spawns in August and September off the coast of Scotland and the Shetland Islands. The Dogger Bank herring spawn in the central part of the North Sea between August and October. Another group spawns in the English Channel from November till January. The further south the spawning grounds, the later the spawning. A fourth herring population spawns in the spring in the Baltic Sea and migrates via the Skagerrak to the North Sea. This is the population which provides the first young herring so desired in the Netherlands. The various species of herring often differ very slightly from each other.

  • Zuiderzee herring

    There was once a group of herring that swam into the Zuiderzee to spawn. Fishermen, dolphins, seals and porpoises made use of this trek to fill their bellies. The Zuiderzee became the IJsselmeer when the Causeway (Afsluitdijk) was constructed and gone were the Zuiderzee herring. Just after the closure, baskets full of herring assembled by the Causeway, but that stopped after several years.

    However in 2006, the TX10 caught an assumedly extinct Zuiderzee herring. The fishermen recognized the population by the shorter and thicker body form. The Zuiderzee herring also has fewer vertebrae. After the Zuiderzee was closed, the populations probably mixed with other herring populations so that they did not become totally extinct.

  • How's life for herring in the North Sea?

    In 1965, a record yield of 1.3 billion kilograms of herring was caught in just one year in the North Sea. Such success didn't last long and the number of herring in the years to follow declined so rapidly that it almost resulted in extinction in 1978. The herring population climbed above the safe boundary by 1989 but still threatened to collapse again several years later.

    By 2003, things improved and the number of adult herring in the North Sea was more than 2 million tons. That's more than two times the amount needed to maintain the population. The fishermen were permitted to catch more, which they did, whereby the herring stock declined rapidly once again. The graph shows that this was the third collapse.

    Maintaining the herring stock and determining a safe amount to catch remains difficult. The fishermen have not been allowed to catch much herring in recent years and that has been effective. In 2011 and 2012, there was an estimated 2.3 billion kilograms of adult herring swimming in the North Sea, which is equivalent to the amount found in the 1950s and 1960s.

  • Reproduction in the North Sea

    In the spawning grounds, all the females in the entire school release the eggs (roe) simultaneously. That's around 10,000 to 60,000 per female. All of the eggs are fertilized simultaneously by the males. Spawning takes place just above the sea floor. The slime-covered eggs sink and attach themselves to the bottom. Depending upon the water temperature, they hatch within 8 to 40 days. The larvae drift to their nursery, which is located primarily along the eastern shores of the North Sea. Young herring remain in the nursery for 2 years, in shallow nutrient-rich water. After two years, they swim to deeper waters. Herring become sexually mature between 3 and 5 years old and spawn every year till they die.

    It used to be that of the tens of thousands eggs laid by each female every year, around seven new herring remained. Nowadays, herring females only produce three new herring per year. The reason is related to the seawater warming up, whereby the herring larvae are hungrier. Furthermore, the composition of the zooplankton is also changing due to the warmer seawater. The hungry herring larvae can't find enough to eat. The result is that fewer adult offspring remain per nest.

  • Distribution and habitat
    Spawning grounds and nurseries of the herring, Ecomare

    Herring swim in the northern hemisphere in the North Sea and Baltic Sea. They also swim along the Dutch coast.

  • Herring as consumption fish

    On a global basis, herring is the fifth most important species for the fisheries. Around 1.5 million tons of herring are caught every year throughout the world. Only anchovies, coal fish, Chilean hake and silver carp are caught more.
    The herring season for the Dutch fleet begins at the end of May and continues till the following March. This fleet fishes herring mostly in the western North Sea and around the Scottish islands. Most of the herring caught is processed into pickled or canned products.
    Only one fifth to one third of the total herring yield is processed into salted herring. This is herring that has not developed any soft or hard roe. They contain more than 15% fat. Much of the Holland Nieuw herring are caught by Norwegian and Danish fishermen.
    Since 2009, all of the Holland Nieuw herring have MSC certification. This quality mark is given to methods of fisheries which take marine nature and environment sufficiently into account.

  • Herring farts

    In the 1980s and 1990s, Swedish-Russian relationships were very tense because Sweden regularly intercepted underwater sounds of submarines that they couldn't find. Even after the East Block collapsed, the noise continued. Studies showed that the noise came from herring farts.

    Herring release gas from their swimming bladders, producing lots of noise under water. Herring farts sound like a high pitched buzz, similar to frying bacon. This is their way to communicate with each other.