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Atlantic herring

life science Maturity 5-7 Next article →

The Atlantic herring, known scientifically as *Clupea harengus*, is one of the most abundant fish species on Earth.

Clupea harengus Gervais
Clupea harengus Gervais

These fish belong to the family Clupeidae and play a vital role in marine ecosystems. They act as a primary link in the food web by converting tiny plankton into energy for larger animals. Because they exist in such massive numbers, they are considered one of the most important fish groups on the planet. Their presence helps maintain the balance of life in the North Atlantic Ocean.

To survive and grow, Atlantic herring use a specialized feeding mechanism. They possess structures in their mouths called gill rakers. These act like fine sieves to filter the water as it passes through their gills. This process allows them to trap zooplankton and phytoplankton, which are tiny organisms floating in the sea. Their diet includes copepods, krill, mysids, and even small fish. By consuming these small creatures, herring move energy up the trophic levels of the ocean.

Herringramkils
Herringramkils

Atlantic herring are famous for their incredible schooling behavior. They are "obligate schoolers," meaning they naturally live in large, organized groups. These schools can consist of thousands, millions, or even billions of individuals. Some North Atlantic schools have been estimated to contain as many as four billion fish. These groups can occupy a massive volume of water, up to 4.8 cubic kilometers. Schooling provides several advantages, such as predator confusion and better orientation during long journeys.

Their movement is highly organized and follows specific patterns. A single stock often travels in a large triangular path. They move between their spawning grounds, their feeding grounds, and their nursery grounds. For example, herring may travel between Southern Norway and Iceland. This movement requires constant cruising, with speeds reaching up to 2 meters per second. They also use excellent hearing to sense danger, allowing the school to react instantly to predators.

Atlantic herring, capture production, million tonnes, 1950-2022
Atlantic herring, capture production, million tonnes, 1950-2022

The life cycle of a herring begins with external fertilization. A female releases between 20,000 and 40,000 eggs into the water. At the same time, males release milt to fertilize them. The eggs are quite small, measuring only 1 to 1.4 mm in diameter. Because they are sticky, the eggs adhere to seaweed or gravel on the sea floor. These eggs only mature if the water temperature remains below 19 degrees Celsius. In warmer water of 14–19 degrees Celsius, they mature in 6 to 8 days. In cooler water at 7.5 degrees Celsius, the process takes 17 days.

Baltic herring from Poland
Baltic herring from Poland

In certain regions, distinct subspecies like the Baltic herring (*Clupea harengus membras*) exist. The Baltic herring is smaller and contains less fat than the true Atlantic herring. This subspecies is culturally significant and was elected the national fish of Estonia in 2007. History shows how sensitive these populations can be to environmental changes. During the mid-16th century, the Little Ice Age caused temperatures to drop. This cooling, combined with overfishing, nearly wiped out the autumn-spawning populations in the Baltic Sea. Today, most fisheries in that area rely on spring-spawning populations.

Heringsfass
Heringsfass

Because herring are so central to the ocean, they support a vast array of predators. Many animals rely on them as a primary food source, including whales, seals, dolphins, and sharks. They are also vital prey for seabirds, cod, and tuna. This relationship makes them a "forage fish," meaning they provide the essential fuel for higher levels of the food chain. Humans also rely on them through large-scale fisheries, particularly in New England and the Canadian Atlantic provinces. Managing these fisheries is essential to ensure that herring populations remain stable for the entire ocean ecosystem.

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File:Heringsfass.JPG
Heringsfass.JPG
File:Clupea harengus Gervais.jpg
Clupea harengus Gervais.jpg
File:Baltic herring from Poland.jpg
Baltic herring from Poland.jpg
File:Herringramkils.jpg
Herringramkils.jpg
File:Atlantic herring, capture production, million tonnes, 1950-2022.svg
Atlantic herring, capture production,...
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