Herring

Herring are a group of forage fish from the order Clupeiformes. They tend to travel in enormous schools near coastlines and fishing banks, favoring the shallow, temperate waters of the North Pacific and North Atlantic Oceans, the Baltic Sea, and the waters off the west coast of South America. Three species within the genus *Clupea*—the type genus for the herring family Clupeidae—account for roughly 90% of all herring caught by fisheries, with the Atlantic herring alone making up more than half of that total. Herring are also found in the Arabian Sea, the Indian Ocean, and the Bay of Bengal.

These fish were central to the history of European marine fisheries, and studying them in the early 1900s helped lay the groundwork for modern fisheries science. As oily fish, they have long been a key food source, often preserved by salting, smoking, or pickling. In the United Kingdom, they were nicknamed "silver darlings."

**Species**

Many species called herring belong to the family Clupeidae. The word "herring" may come from the Old High German *heri*, meaning "host" or "multitude," a nod to the massive schools they form. The genus *Clupea* includes just two species: the Atlantic herring (the type species), found in the North Atlantic, and the Pacific herring, mainly in the North Pacific. While some subspecies have been proposed for both, their biological validity remains uncertain.

Several other Clupeidae species are also commonly called herring, as listed by FishBase and assessed by the International Union for Conservation of Nature. Beyond these, some fish—like the lake herring, which is actually a salmonid—are called herring in certain places, even if they are only distantly related or share a few traits. What is called a herring in one region may go by another name elsewhere.

**Characteristics**

Members of the genus *Clupea* belong to the larger family Clupeidae, which includes herrings, shads, sardines, and menhadens—about 200 species with similar features. These silvery fish have a single, soft dorsal fin without spines, no lateral line, and a protruding lower jaw. Size varies by subspecies: Baltic herring (*Clupea harengus membras*) are small, 14 to 18 cm (about 5.5 to 7 inches); the true Atlantic herring (*Clupea harengus harengus*) can reach about 46 cm (18 in) and weigh up to 700 g (1.5 lb); and Pacific herring grow to about 38 cm (15 in).

**Life Cycle**

At least one population of Atlantic herring spawns every month of the year, with different groups spawning in spring, summer, autumn, or winter at distinct times and places. Greenland herring spawn in water just 0–5 metres (0–16 feet) deep, while North Sea bank herring spawn at depths up to 200 m (660 ft) in autumn. Eggs are laid on the seabed—on rock, stones, gravel, sand, or beds of algae. A female deposits between 20,000 and 40,000 eggs, depending on her age and size, averaging about 30,000. Before spawning, the genital organs of mature herring grow to about one-fifth of the fish's total weight.

The eggs sink and stick in layers or clumps to gravel, seaweed, stones, or any other surface they settle on, held by a mucous coating. If the layers are too thick, the eggs suffer from oxygen depletion and often die, tangled in mucus. They need substantial water movement, usually from waves or coastal currents. Survival is highest in crevices or behind solid structures, where predators have less access. Individual eggs measure 1 to 1.4 mm (3⁄64 to 1⁄16 in) across, depending on the parent fish's size and the local race. Incubation takes about 40 days at 3 °C (37 °F), 15 days at 7 °C (45 °F), or 11 days at 10 °C (50 °F). Eggs die at temperatures above 19 °C (66 °F).

At hatching, larvae are 5 to 6 mm (3⁄16 to 1⁄4 in) long, with a small yolk sac that is absorbed by the time they reach 10 mm (13⁄32 in). Only the eyes are well pigmented; the rest of the body is nearly transparent, making them almost invisible underwater in natural light. The dorsal fin forms at 15 to 17 mm (19⁄32 to 21⁄32 in), the anal fin at about 30 mm (1+3⁄16 in), and the ventral fins become visible with a well-forked tail at 30 to 35 mm (1+3⁄8 in). By about 40 mm (1+9⁄16 in), the larva starts to look like a herring. Herring larvae are very slender and can be distinguished from other young fish in their range by the vent's location near the tail base, though telling them apart from sprats in early stages requires careful examination. At one year, they are about 10 cm (4 in) long, and they first spawn at three years.

**Ecology**

**Prey**

Herring feed on copepods, arrow worms, pelagic amphipods, mysids, and krill in the pelagic zone. In turn, they are a key prey item for larger predators. The reasons for their success remain unclear, though one idea points to the huge, fast-moving schools they form. Young herring eat phytoplankton, then shift to larger organisms as they mature. They also consume zooplankton—tiny animals in surface waters—along with small fish and fish larvae. Copepods and other tiny crustaceans are the most common zooplankton in their diet. During daylight, herring...